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·WORLD HEALTH ORGANIZATION
MONOGRAPH SERIES
No. 27
CHEMOTHERAPY OF MALARIA

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·CHEMOTHERAPY
OF MALARIA
SIR GORDON COVELL, CIE, MD
Adviser on Sfafarla, afinistry of Health
Director, Malaria Laboratory, Hortor Hospital, Epsom, Surrey, England
G ROBERT COATNEY, Ph.D.
Laboratory of Tropical Diseases, National Aflcroblological Institute,
National Institutes of Health, Bethesda, MD, USA
JOHN W FIELD, CMG, MD
Director, Institute for Afedical Research,
Kuala Lumpur, Federation of Malaya
JASWANT SINGH, MB, Ch B, DPH, DTM & H.
Director, Malarla ſostitute of India,
Delhi, India
WORLD HEALTH ORGANIZATION
PALAIS DES NATIONS
GENEVA
1995

·NOTE
Authors alone are responsible for views
expressed in the Monograph Series of the
World Health Organization
The mention of manufacturers' products does not imply that they are endorsed or
recommended by the World Health Organization in preference to others of a similar
nature which are not mentioned Propnetary names of such products are distinguished
by at ipatial capital letter
PRINTED IN SWITZERLAND

·CONTENTS Page 7 Introduction 9 Chapter 1 Definition of terms and hustoncal review Definition of terms Histoncal review 9 10 15 Chapter 2 The rationale of malana chemotherapy The chemical approach The biological approach 15 23 32 32 37 Chapter 3 Individual compounds 10 common use Quinine Primaquino and other 8-aminoquinolines Mepacrine Chloroquino and other 4-aminoquinolines Proguana Pyrimethamino 39 43 46 31 Chapter 4 Drug resistance in malaria $4 $7 $9 Resistance to the common apumalanal drugs Proguant resistance Cross resistance Origin lod mechanism of drug resistance Commentary 64 65 67 Chapter 5 The clinical use of antimalanal drugs 69 70 The aims of malana chemotherapy The confusions of dosage The malana patient The symptomer camer Individual drug prophylaxis Collective drug prophylaxis 8$ 86 39

·Page
Annexes
97
Annex 1 Summary of suggested dosago
Annex 2 Base-content of tablets
Annex 3 Physical data regarding salts
Annex 4 Synonyms of antimalanal drugs
99
100
101
103
Selected bibliography
Index
119

·INTRODUCTION At its fourth session, beld in Kampala, Uganda, 19 December 1950, the Expert Committee on Malana of the World Health Organization expressed the opinion that it was desarable to bring together for the benefit of the medical profession Sactual information on the properues of acumalarial drugs, and advised the appointment of a drafting committee to undertake the task In accordance with this recommendation, a commuttee was appointed with the following members Sir Gordon Cosell (Chairman), Dr G Robert Coacey, Dr John W Field, and Licutenant Colonel Jassant Singh The fact that the four members of the committee are resident in countries as far distant from one another as England, the United States of America, Malaya, and India has necessarily delayed the completion of the work It has not been possible for the caure committee to meet at any one time during the preparation of the text, but the Chairman has been able to hold personal discussions from time to une with Dr Coatncy and Dr Field and has mantained contact with Lieutenant Colonel Jaswant Siogh by correspondence The committee wishes to ackoowledge with thanks the assistance received from Dr W Clark Cooper and Dr Honard W Bond, USA, Dr T Wilson and Dr J F B Edeson, Malaya, and Dr A P Ray and Dr H L Damı of the Malaria Iasutute of India, Delhi

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·CHAPTER 1 DEFINITION OF TERMS AND HISTORICAL REVIEW Definition of Terms The terminology followed in this study is in conformity with that suggested in the monograph Malaria terminology, issued by the World Health Organization in 1953, VIZ Blood schizontocide * a drug which acts on asexual parasites in the blood Tissue achizontocide a drug which acts on asexual parasites in the tissues (a) primary fissue schizontocide a drug which acts on preerythrocylc (primary cxoerythrocytic) forms, (b) secondary tissue schizontocide a drug which acts on secondary exoerythrocytic forms Gametocytocide a drug wbich acts on the sexual forms of the parasite Sporontocide a drug which acts on the sporogonic forms in the mosquito Suppression implies the prevention of clinical symptoms by action on asexual parasites in the blood It may be remporary, that is, operative only while the drug is being taken, or permanent, denoting that no attack will supervene even after the drug has been discontinued Clinical cure indicates that the immediate symptoms of an attack have been relieved and that the patient has apparently recovered Radical cure implies elimination of the parasite from the body, whether by natural recovery or as the result of treatment Suppressive cure implies radical cure brought about while the patient 13 receiving suppressive medication Spontaneous recovery is a term applied to clinical or radical cure brought about by nature, in the absence of specific medication The word prophylaxis is commonly used for any method of protection from discase and, therefore, when applied to chemotherapy, it should This word 11 sometimes, tpelt schizosickle hich in etymologially racorrect enerally acepted that if the first clement of compound word is Groek the better 1 inserted before the sufix Lata the letter It is o - 9 - ·10 CHEMOTHERAPY OF MALARIA properly be designated drug prophylaxis When applied to a community, the term collective drug prophylaxis is used, when to an individual, the term individual drug prophylaxis Clinical drug prophylaxis is a term someumes appued when the object is merely to prevent the occurrence of overt attacks during such time as the drug is administered Action on the asexual erythrocytic forms is, however, already covered by the word suppression, and it is suggested that the word prophylaxis when applied to chemotherapy should be restricted to action on sporozoites or other pre erythrocytic forms (equivalent to the true causal or causative prophylaxis of James) Names of antimalarial drugs ending with “in(e)" are written with an "e" by some authors and without an "e" by others For the sake of uniformity, in thus monograph all such words, unless they are trade names, are written with an "e", for example, chloroquine, amodiaquine, pamaqune, mepacrine, primaquine in proprietary names of drugs a capital is used for the initial letter, in son proprietary names the initial letter is given in lower case Historical Review Before the outbreak of the first World War, the only specific aptimalarial drugs known were the cinchona alkaloids, of which the most commonly used was quinide Coachona is the name given by Lindaeus to a family of plants indigenous to the eastern slopes of the Andes in memory of the Countess of Chinchon, wife of an early Viceroy of Peru, to whom legend attributes the introduction of the bark to Europe Historical evidence does not support this story, but it is a fact that the bark of the quina quina tree, now known as cinchona, was introduced into Europe from South America by the Spantards about the year 1640, and was used in Spain and Italy for the treatment of fevers from that time onward Powdered bark had reached England by 1655 and was prescribed as such for the treatment of intermittent fevers for the next 200 years It was used in North America during the War of Independence by the troops of both the contending armies The bark is said to have been introduced into India as early as 1657 During the latter half of the 18th century it was used extensively in that country, where it was popularized by the surgeons of the numerous ships trading 19 eastern waters Dr James Lind treated over 400 cases of intermittent or remittent fever in Bengal with cinchona bark in the year 1765 with ercellent results In the first half of the 19th century, cinchona passed through a phase of unpopularity in India, principally due to the malign influence of a certain Di Johnson, a naval surgeon, who visited Calcutta in 1804 He treated bus first fever patient with cinchona bark and faded ·TERMS AND HISTORICAL REVIEW 11 to effect a cure He bled and purged his second patient, who recovered, and thenceforth advocated a line of treatment of which the main feature was drastic purgation, salivation, and vedesection After a brief sojourn 10 India he returned to England, where he published a treatise on tropical diseases in which the administration of cinchona bark as a remedy for malaria was vehemently condemned As a result, the use of the bark 13 India was practically abandoned, and for many years it was used merely as a tonic, in minute doses, after the subsidence of the fever At this perod as much as from 800 to 900 grains (50-60 g) of calomei were commonly prescribed for the treatment of a single attack of malana From about the middle of the 19th century, the popularity of cinchon2 bark was re-established, largely through the influence of Edward Hare, who came to India in 1839 and was in medical charge of British troops in the Burmese War and during the siege of Delhi at the time of the Indian Mutiny At this time the use of cinchona bark for malaria was frowned upon by the authorities, but Hare came across some of the old writings of James Lind, extolling its virtues, and decided to give it a trial Over a period of nine years he treated some 7,000 cases of fever, with a mortality of less than 12% In 1820, quinine and cinchonine were isolated from the bark by two French scientists, Caventou and Pelletier The dominant position subsequently attained by quinige in the treatment of malaria as compared with the other alkaloids of cinchona was largely due to the fact that it was the first to be isolated In point of fact there is little difference as regards antimalanal properties between it and the three other principal alkaloids present Cinchona cultivation was established in Java by the Dutch in 1854, with scedlings brought from Bolivia and Peru by the botanist Hasskarl In 1860, the British geographer Clements Markham obtained seeds from Peru, from which plantations were stocked in India and Ceylon, where the industry flourished for a while, but during the period 1880-90 reckless over production led to a fall in prices which proved ruinous The planters in Java managed to survive the slump, and at the outbreak of the second World War about 97% of the world s supply of quinine came from that country The evolution of the synthetic anumalarials now in usc makes an interesting story Quinine is an effective drug for treatment of the clinical attack in most malanal infections, and it is doubtful whether any of the synthetic antimalarials would have beçn evolved but for the occurrence of the two World Wars The fact that the Germans were cut off from all sources of quinine dunng the first World War was the sumulus which inspired the intensive search for synthetic substitutes skich resulted in the ·12 CHEMOTHERAPY OF MALARIA production of Plasmochin (now known as pamaqune) and later of Atebna (now known as meparine) When this work was planned in the early 1920s, all attempts to synthesize qunne had failed, this was finally accomplished in 1944 12 But Guttmann & Ehrlich,14 in 1891, had discovered that methylene blue effectively stains malaria parasites and had tried the dye on patients suffering from vivax malana, some of whom were relieved of their symptoms The results were not sufficiently im pressive to warrant the substitution of methylene blue for quinine, but they were destined to play an important part in shaping the course of subsequent researches In their work at Elberfeld,23 the Bayer research chemists were greatly helped by a technique of testing antimalarial compounds in canaries infected with Plasmodium relictum, this system for evaluating compounds was introduced by Roehl in 1924 With Ehrlich's early observations in mind, they introduced a basic side chain into the formula of methylene blue, an easier procedure than effecting similar alterations in the quinine structure One of the resulting compounds showed considerable activity against bırd malaria The next step was to attach various side chains to the quinoline nucleus, which is present a quinine This line of approach finally resulted in the synthests of pamaquine, which in 1925 was selected for clinical investigation from a large number of allied compounds Pamaquine thus became the first synthetic quinoline compound to exhibit effective action against human malaria parasites, and the first drug of any sort with a destructive effect on the gametocytes of P falciparum Although pamaquine has remarkable antimalarial properties, it was unsuitable as a therapeutic agent in several respects, the most important being its relatively high toxicity and the fact that it has little action on the asexual erythrocytic forms of P falciparum The German scientists accordingly embarked on further studies They attached the basic sidechain which had been evolved for pamaqune to other heterocyclic nuclei, and in 1930 finally produced the acridine compound now known as mepa- This proved to be relatively non toxic and was the first synthetic drug with a definite destructive action on the asexual blood forms of P falciparum Approximately 12,000 different compounds were tested in the course of this work After preliminary tests on human malaria in Germany, pamaquine and mepacrine were subjected to an extensive series of field trials in various parts of the world under the auspices of the League of Nations These trials, made in Algeria, Italy, Malaya, Roumadia, and the USSR, brought clear and decisive proof of the high suppressive action of mepacrine in all forms of human malaria, but left some uncertainty as to the possible toxic effects of long-continued administration Sinton & Bird 31 in India made the unexpected discovery that pamaquine caused a marked reduction 10 crine ·TERMS AND HISTORICAL REVIEW 13 the relapse rate of vivax malaria--a finding of fundamental importance in subsequent researches on the 8 aminoquinolines The protective properties of both pamaquine and mepacrine were studied by James and hus colleagues in England Pamaquine proved to be a causal prophylactic against P falciparum and a partial causal prophylactic in vivax infections, though only at a dosage dangerously high for routine use Mepacrine in a daily dosage of 100 mg was shown to be an effective suppressant for both vivax and falciparum infections, but at that time fears were expressed that this amount taken over an extended period might exert a harmful action The Germans went on to synthesize two other compounds, Resochia (chloroquine) and Sontochin (sontoquine) Chloroquine was synthesized as early as 1934, but after a few human tests it was discarded on the ground that it was too toxic Sontoquine, with its extra CH, group, was later produced in an attempt to neutralize these effects, and was undergoing field trials when the second World War broke out in 1939 In the second World War, the Allies in their turn were cut off from the main sources of quinine when the Japanese overran Indonesia, and an enormous volume of research on antimalarials was undertaken on both sides of the Atlantic In the United States of America an intensive inves tigation of the absorption, distribution, excretion, and metabolic trans formation of mepacrine was undertaken By mid 1943, it was shown that the drug was extensively localized in the tissues and that its effectiveness was a function of the concentration in the plasma This information led to the adoption of improved dosage schedules and its general acceptance as an effective therapeutic agent in the management of malaria The properties of mepacrine were explored, though on a very much less extensive scale, in the United Kingdom In Australia, during the period 1943 5, an extensive series of tests, in which more than 800 volunteers from military units took part, was conducted by an Army medical research team? These tests confirmed and amplified the earlier work on the suppressive value of mepcrine, and also proved that a daily dose of 100 mg of the drug could be continued for an indefinite period without serious ill-effects It was the routine use of mepacrine as a suppressant, based on these findings, which enabled the Allied armies in the south west Pacific and south-east Asia commands to be maintained in a fighting condition at a time when the Japanese troops opposing them were gravely hampered by malaria casualues The French in North Africa studied the properties of soptoquine, established its high antimalarial activity, and ſound that it was well tolerated Following the occupation of North Africa by the Allies, this information became available to the United States investigators, who synthesized a large series of 4-aminoquinoline derivatives, nine of which were givea limited ·12 CHEMOTHERAPY OF MALARIA 11 production of Plasmochin (now known as pamaquine) and later of Atebria (now known as mepacrine) When this work was planned in the early 1920s, all attempts to synthesize quinine had failed, this was finally accomplished in 1944 52 But Guttmann & Ehrlich, in 1891, had discovered that methylene blue effectively stains malaria parasites and had tried the dye on patients suffering from vivax malana, some of whom were relieved of their symptoms The results were not sufficiently impressive to warrant the substitution of methylene blue for quinine, but they were destined to play an important part in shaping the course of subsequent researches In their work at Elberfeld,23 the Bayer research chemists were greatly helped by a technique of testing antimalarial compounds in canaries infected with Plasmodium relictum, this system for evaluating compounds was introduced by Roehl in 1924 With Ehrlich's early observations in mind, they introduced a basic side chain into the formula of methylene blue, an easter procedure than effecting similar alterations in the quinine structure One of malaria nucleus in the investigation from a large number of allied compounds Pamaquine thus became the first synthetic quinoline compound to exhibit effective action against human malaria parasites, and the first drug of any sort with a destructive effect on the gametocytes of P falciparum Although pamaquine has remarkable antimalarial properties, it was unsuitable as a therapeutic agent in several respects, the most important being its relatively high toxicity and the fact that it has little action on the asexual erythrocytic forms of P falciparum The German scientists accordingly embarked on further studies They attached the basic sidechain which had been evolved for pamaquine to other heterocyclic nucles, and in 1930 finally produced the acridine compound now koown as mepa- This proved to be relatively non toxic and was the first synthetic drug with a definite destructive action on the asexual blood forms of Pfalciparum Approximately 12,000 different compounds were tested in the course of this work After preliminary tests on human malaria in Germany, pamaquine and meparrine were subjected to an extensive series of field trials in various parts of the world under the auspices of the League of Nations These trials, made in Algeria, Italy, Malaya, Roumania, and the USSR, brought clear and decisive proof of the high suppressive action of mepacrine in all forms of human malaria, but left some uncertainty as to the possible toxic effects of long-continued administration Sinton & Bird 1 in India made the unexpected discovery that pamaqune caused a marked reduction in Crine ·TERMS AND HISTORICAL REVIEW 13 the relapse rate of vivax malaria-a finding of fundamental importance 10 subsequent rescarches on the 8 aminoquinolines The protective prop erties of both pamaquine and mepachine were studied by James and his colleagues in England Pamaquine proved to be a causal prophylactic against P falciparum and a partial causal prophylactic in vivax infections, thougn only at a dosage dangerously mgh for touunt use Mepachne m a daily dosage of 100 mg was shown to be an effective suppressant for both vivax and falciparum infections, but at that time ſears were expressed that this amount taken over an extended period might exert a harmful action The Germans went on to synthesize two other compounds, Resochin (chloroquine) and Sontochin (sontoquine) Chloroquine was synthesized as early as 1934, but after a few human tests it was discarded on the ground that it was too toxic Sontoquine, with its extra CH, group, was later produced in an attempt to neutralize these effects, and was undergoing field trials when the second World War broke out in 1939 In the second World War, the Allies in their turn were cut off from the main sources of quinine when the Japanese overran Indonesia, and an enormous volume of research on antimalarials was undertaken on both sides of the Atlantic In the United States of America an intensive inves tigation of the absorption, distribution, excretion, and metabolic trans formation of mepacride was undertaken By mid 1943, it was shown that the drug was extensively localized in the tissues and that its effectiveness was a function of the concentration in the plasma This information led to the adoption of improved dosage schedules and its general acceptance as an effective therapeutic agent in the management of malaria The pro perties of mepacrine were explored, though on a very much less extensive scale, in the United Kingdom In Australia, dumng the period 1943 5, an extensive series of tests, 10 which more than 800 volunteers from military ututs took part, was con ducted by an Army medical research team? These tests confirmed and amplified the earlier work on the suppressive value of mepacrine, and also proved that a daily dose of 100 mg of the drug could be continued for an indefinite penod without serious ill effects it was the routine use of mepacrine as a suppressant, based on these findings, which enabled the Allied armies in the south west Pacific and south-east Asia commands to be maintained in a fighting condition at a time when the Japanese troops opposing them were gravely bampered by malaria casualties The French in North Africa studied the properties of sontoguine, established its high antimalarial activity and found that it was well tolerated Following the occupation of North Africa by the Allies, this information became available to the United States investigators, who synthesized a large series of 4-aminoquinoline derivatives, diae of which were given limited ·16 CHEMOTHERAPY OF MALARIA Graphic formulae H 1 H- II Hbenzeno nag Pyndiac ning pyrimidine ning 65 10 quinoliae ring acriding nog Certain arsenical compounds, such as Stovarsol and Salvarsan, which have some action in vivax malaria, are benzene derivatives The quinoline ring has much greater importance, and is the basis of the principal cinchona alkaloids and of the 4-amino- and 8 aminoquinolines The acridine ring is the basis of mepacrine, chloroquine may be regarded as mepacrine with one ring removed, sontoquine and amodiaquine are modifications of chloroquine Quinine is a 6 methoxyquinolne, while pamaquine, pentaquine, isopentaquine, and primaquine are 6-methoxy-8 aminoquinolines, that is, they are quinoline derivatives with a methoxy or amino group at the sixth or eighth position of the quinoline nucleus, counting from the nitrogen atom In proguanil, the benzene ring is attached to a biguanide chain, pyrimethamune is a substituted pyrimidine Cinchona alkaloids Cinchona contains more than 20 alkaloids, but only four are of importance quinine, quinidine, cinchonine, and cinchonidine Cipchong febrifuge and totaquine are mixtures of alkaloids derived from the bark, the difference between them being that samples of the former may vary in composition, while in the latter the percentage of total crystallizable alkaloids and the quipine content must conform to a prescribed standard Chemically, qupine is a compound of complex molecular structure, visualized as being made up of three parts the quinoline component (6-methoxyquinoline), the qunuclidine part (a complex ring with an attached vinyl group), and the connecting link (a hydroxylated methylene ·RATIONALE 17 group) Quinidine is an optical isomer of quinine, cinchonine and cin chonidine are optical isomers lacking the methoxy group Graphic formula HOCH-CH- NCH, CH,0 CH, CH CH,CHCHCH=CH, quin de Various minor modifications of quinine have been studied in an attempt to evolve more active compounds but none of them has proved of practical value for the treatment or prophylaxis of human malaria 8 aminoquinolmes Mention has already been made of the early German researches in which methylene blue was shown to have some inhibitory effect on plasmodia Schulemann and his colleagues at Elberfeld 23 found that by replacement of one of the methyl groups of methylene blue with a basic dialkylaminoalkyl group antimalarial activity was considerably enhanced It seemed likely that the activity of the quinoline nucleus present in quinine might also be increased by the introduction of a similar basic side chain It was by this line of reasoning that, in 1924, pamaquide was evolved Graphic formulac CHEN CH, CH, CH, -N CH, CH, CH CH, CH methylene blue CH, CH CH,0 CH,O Cols Сн, NHCH(CH), NO CH, *HCHCHN CH, pamaquine ·18 CHEMOTHERAPY OF MALARIA Pentaquine, isopentaquine, and primaquine, evolved as the result of re-examination of the 8 aminoquinolines in the United States of America during and after the second World War, differ from pamaquine in the type of alkylamino chain attached to the 6-methoxyquinoline ring Graphic formulae CHO CH,09 NH(CH) NHCH(CH3 NHCH(CH), NHCH(CH), CH, pertaquine isopettaqu100 CH20- NHCH(CH2)2NH, prima quine 9-aminoacridines Mepacrine is an acridine dye, in which the quinoline ring is broadened to form the acridine In the hope of decreasing toxicity, the German scientists replaced the quinoline ring of pamaquine by the acridine, which is relatively closely related to quinoline By introducing the chlorine atom and a methoxy group sato che acridioe ring they finally produced mepelcriae, in which the side chain is opposite the ring nitrogen as in quinine It has been suggested that the activity of mepacrine is due to the capacity of the molecule to exhibit a form of tautomerism involving the lability of a hydrogen atom which can assume two alternative positions in the molecule Crophic formula CH, CH, NHCH(CHN CH, CHO- C1 mopactine ·RATIONALE 19 4 aminoqurolines Studies carried out in Germany on this group of compounds followed the work on pamaquine and mepactine un logical sequence The mepacrine molecule was broken down into its coostituent parts in an attempt to throw further light on the relationship between chemical structure and aptimalanal activity The removal from mepacrise of the methoxy bearing ning gave rise to chloroquine (originally known as Resochin) As already noted, soatoquine differs from chloroquine in having an extra methyl group on the quinoline nucleus Another member of the group, amodiaquine (Camaquin), in which the alkylamuao side chala is replaced by a substituted anilino group, has also proved to be an effective blood schizontocide These three drugs, together with mepacrioc and quiasne, all bear a structural similanty to one another All except mepacrine are quinolines, and mepacrine may be regarded as containing the quroline nucleus , and all have side chains opposite the ring nitrogen It is probable that they all have a similar fundamental action against malana parasites Graphe formular CH, NHCH(CH), NK CH CH, NUCH(CHD, CHE chloroquipe CH, CH, sonioquine CH, -OH amodiaquinc Sulfonamides Since Diaz de León 1a 1937 first claimed to have successfully treated cases of vivax malaria with a svifa compound, many of these have been tested against avan, sımsan, and human malaria Although none of the ·20 CHEMOTHERAPY OF MALARIA group has proved of practical value in the chemotherapy of malana, these studies have helped to elucidate a number of problems and have served as a guide in the synthesis of other compounds Sulfanilamide will cure blood-induced knowlesi malana, and many other derivatives of sulfanilamide, such as ct as true causal prophylactics against while the fact that the antimalarial ac by p aminobenzoic acid has shed light on the metabolic requirements of plasmodia generally One of the sulfonamides—metachloridine, which is structurally similar to sulfadiazine--s said to be active against quartan malaria, but agaiost falciparum infections it has proved ineffective Graphic formula -SO,NH NH, metachloridine Biguanides The work which led to the recognition of the antimalarial properties of this group of drugs began with the investigation by Curd, Davey & Rose *** of certain pyrimidine derivatives, prompted by a consideration of the antimalarial activity of the pyrimidine-substituted sulfanilamides A second reason for studying the pyrimidines was the similarity between the formulae of mepacrine and riboflavine, it was thought that the activity of mepacrine might be due to a competition with riboflavine for certain enzyme systems in the malaria parasite A third reason was the characteristic of resonance * possessed both by the pyrimidines and by mepachine In these researches the first compound found to be really active against bird malaria was number 2666 This compound contains the substituted pyrimidine ring and an alkylamino group attached to a pitrogen atom, close inspection of the formula shows both extended and true amidine systems Another compound, 3349, a guanidine derivative of 2666, is even richer in amidine groups, it was the first of the series to show activity against human malana This compound is capable of existing in several tautomeric forms, and at therefore seemed possible that a pyrimidine ring as such was not essential and could be substituted by a biguanide group, which is capable of similar tautomertso Eventually, the highest activity • Resonance is the phenomenon due to the transition from an electron configuration into another of the same spat al nuclear structure in a molecule It is also called mesomers and must not be confused with tautomerism in which the spagal arrangcment of the atomic Duclei 13 ditferent for the two tautomers -ED ·RATIONALE 21 in place of the more complex diethylaminoethyl group Graphic formulae син, NHCH CHỌN H CH, CI- CH, 2066 RP C,H, NH II H NHCH CHỌN н C,H, CH, 3349 RP NH NH H1 H11 N-CN-C-NHCH(CH3)2 progan! Diaminopyrimidines Hitchings and his colleagues in the United States of America found that several substituted diaminopyrigudines are powerful antagonists of pteroylglutamic acid in cultures of Lactobacillus case. The formal analogy between 2 4-diamino-5 p-chlorophenoxypyrimidine and proguapıl and the finding that proguanil was also an antagonist of pteroylglutamic acid suggested that the pynmedine compound might have antimalanal activity A number of members of the group were studied and it was found that those with a 5 phenyl substituent were the most active Substitution of a halogen or nitro group in the para position of the phenyl group was found to enhance activity Substitution of an alkyl group in the 6 position of the pyrimidine also increased activity and in the case of 5 p-chlorophenyl derivatives a peak of activity was reached with the 6-ethyl compound (pyrimethamine) which proved 60 times as active as proguanil against P gallinoreum and 200 times as active against P bergker The active form of proguapıl has been shown to be a metabolite which bears a stnking resemblance to pyrimethamine What was originally proposed as a purely formal analogy is now, therefore, to be regarded as ·22 CHEMOTHERAPY OF MALARIA a real structural analogy It is not surprising to find that the two compounds resemble one another closely in their antimalarial properties There is also evidence that pyrimethamine itself may give rise to an active metabolite Graphic formulae NH, NH, HN C1 HAN CI N--CH, CH, CH metabolite of proguanil pyrimetamine Naphthoquinones Hydrolapachol and two other quinones have been found to possess some antimalarial activity and this has led to the synthesis of a number of other naphthoqunone derivatives Although some members of the group have shown considerable activity against avian plasmodia their effect in human malaria has been generally disappointing presumably because they undergo rapid degradation in the human body One of them, however, has been shown to have considerable resistance to metabolic deactivation, namely, Lapinone (M 2350), which has a hydroxylated Co side chain It has been claimed that this drug has definite suppressive activity against vivar malaria, but this finding needs confirmation Graphic formula CH,(CH,,CH, (CH), -OH | CH,CH2-CH, OH Lapinone 2 Organometallic compounds 11an na that certain metallic nber of arsenical ine (Salvarsan), neoarsphenamine (Neosalvarsan), Mapharsen, acetarsol (Stovarsol), and carbarsone--but although arrested development of the parasites and relief ·RATIONALE 23 of symptoms have been recorded in vivax infections, there has been no consistent diminution in the relapse-rate Preparations of mercury, antimony, and bismuth have also been used for malaria with little success A bismuth compound-sodium bismuth thioglycollate, known as Thio Bismol-has been found useful for limiting vivax and malariae infections in the treatment of neurosyphilis by malaria therapy It has an inhibitory action on the half and three quarter grown forms of the parasite and is used in vivax malaria for converting a quotidian type of fever into a tertian by destroying all except one generation of parasites Neoarsphenamine has been used similarly in the Netherlands Antibiotics Many antibiotics have been tested for antimalarial activity Some action was shown by certain members of the group-for example, Chloromycetin, Aureomycin, Terramycin, and Fumagıllın-but in no case have the results indicated that the drug would prove of practical value in the treatment or prophylaxis of malaria Miscellaneous A number of amino alcohols derived from phenanthrene and naphthalene have been reported as showing antimalarial activity One of the phenanthrene derivatives (SN 1796) has been tested against human malaria, but the response was poor Isolation of the active metabolite of proguanil has recently stimulated researches on substituted triazine derivatives and some of the compounds have been found more active than proguanil against experimental infections In the field of aripocresols and orthocresols, a compound designated SN 6771 has been found to display some activity against human malaria A number of pantothenic acid derivatives, tbiocarbamates, diamidines, dicoumarins, dibenzamidines, hormones, vitamins and their analogues, sulfabiguanides, guanidines, thio derivatives, cinnolines, benzoacridines, and pyridoacndides have been tested, but in no case has any compound been discovered which could compete with the established antimalarial drugs The Biological Approach Life cycle of the malaria parasite More than 50 years have passed since the mode of transmission of malana was proved and the existence of an asexual phase in man and a sexual phase in the mosquito was demonstrated The latter was followed ·24 CHEMOTHERAPY OF MALARIA out in full as early as 1898, but for many years one question regarding the former remained unanswered What happens to the parasite during the period between the injection of the sporozoites into the body and the first demonstrable appearance of asexual forms in the peripheral blood ? Schaudıon,22 in 1902, reported that he had actually seen a sporozoite penetrate a red blood-cell, and this finding was at first generally accepted But as the years went by and no one was able to repeat this observation, despite the most intensive search, it gradually became evident that Schaudinn had been mistaken, and that the parasite must undergo another phase of development in the body during the prepatent period, as indeed bad been suspected by Grassi as early as 1900 Raffaele, 21 who described unpigmented parasites in avan malaria in 1934, was the first to recognize that these forms represented a definite phase of development in the tissues as distinct from that occurring in the blood James & Tate,"? in 1937, described the experythrocytic schizogony of P gallinaceum in the brain capillaries of the fowl, but the mystery of what happens during the period immediately after infection remained for a while unsolved In 1940, however, Shortt and his colleagues 30 in India and Mudrow 20 in Germany independently observed pre erythrocytic forms of avian malaria during the prepatent period This work was amplified in the United States of America by Huff & Coulston 15 who, in 1944, described in detail the complete development of the pre erythrocytic stages of P gallinaceum Between 1943 and 1945, Fairley and his co workers ? in Australia carried out some highly significant studies on human malaria by which it was shown that after infection by mosquito bites the sporozoites circulate in the blood for about half an hour, after which they disappear This was proved by inoculating large quantities of blood into volunteers in whom malaria was produced if the blood was drawn from the donor within half an hour of infection Subsequently the blood of the donor was innocuous for six days after inoculation with P falciparum and for eight days after that with P vivar At this time Shortt and Garnham in England had just begun a series of researches on mammalian malaria that were destined to achieve far- Teaching results In 1948, after massive infection by the bites of heanly infected mosquitos, which were afterwards ground up and injected parenterally into a rhesus monkey, pre-erythrocytic forms of P cynomolgı were observed in a section of liver removed seven days later 23 Subsequently, less mature stages of the parasite were found in the liver of other monkeys similarly infected, the earliest to date being in sections excised on the second day 23 It has also been proved that in monkey ·RATIONALE 25 malaria exoerythrocytic parasites can persist in the liver after blood infec tion has been estabúshed These forms are thought to be responsible for the phenomenon of late relapse in cynomolgi and vivax malaria As such relapses are not encountered in falciparum infections, it is believed that such a phase does not occur in this type of malaria The demonstration of tissue forms of P cynomolgi in the monkey made it practically certain that a similar phase exists in human malaria, and this was soon established for both Pyrax and P falciparum This work was carried out by Shortt and his team in London, in collaboration with the staff of Horton Malaria Laboratory 25 26 In December 1953, Garnham and his co workers succeeded in demonstrating pre-erythrocytic forms of P ovale in the human liver 11 Two years earlier, Garnham 10 had demonstrated in the liver of a monkey pre erythrocytic forms of P mu which closely resembles P malariae in all essential features The existence of a pre erythrocytic phase of P falciparum has been confirmed by Jeffery and his colleagues in the United States of America The bfe-cycle of the malaria parasite may be summarized as follows When an infective mosquito bites a new host, sporozoites are inoculated into the blood stream There they circulate for about half an hour, after which they disappear It is presumed that many of them are arrested in the liver although the earliest stage of development in that organ has not yet been observed As stated above, however, pre-erythrocytic forms of P cnomolgı have been demonstrated as early as the second day after infection The tissue schizont, as the parasite is now called, increases in size and divides to form thousands of minute merozoites The cell envelope ruptures, setting free the merozoites into the surrounding tissues Many of these probably attach themselves to red cells in the liver stousoids, but it is believed that, except in falciparum malaria, some penetrate other liver cells and either remain dormant or repeat the cycle of schizogony These are the forms to which late relapses in vivax malaria have been attributed The young merozoites which enter the blood stream are now called trophozoites It is generally believed that the parasite actually penetrates the red cell, but some observers hold that it remains on the outer surface The trophozoites increase in size and become schizonts These ultimately rupture, discharging merozoites, which enter other red cells and repeat the process of schizogony After a while certain merozoites are produced which become sexually differentiated as male and female gametocytes Should a mosquito bite the host at this time the sexual forms are taken up and conjugate in the insects stomach to form a tygoit This lengthens to become an ookidete or vermicule, which penetrates the stomach wall and comes to rest on the outer surface, where it is known as an oocyst The cyst grows and divides into thousands of elongated ·26 CHERIOTHERAPY OF MALARIA bodies called sporozoites When the cyst ruptures, many of the sporo zoites find their way into the salivary glands, whence they are injected into a new host when the mosquito next takes a blood meal Drug action in relation to different stages of the life cycle In theory, a drug may act on the malaria parasite in any of the following Ways (1) against the sporozoites when they first enter the human body, (2) against the primary tissue or pre erythrocytic forms of the parasite, (3) against the asexual parasites in their erythrocytic phase, (4) against the sexual parasites in their erythrocytic phase, (5) against the late exoery throcytic or secondary tissue phase, to which the phenomena of latency and late relapse in vivax and possibly in quartan malaria have been attributed, and (6) against the sporogonic forms in the mosquito phase of the life-cycle 1 L halan are acri. 1 quine), (d) the 8 aminoquinolines (pamaquine, primaqune), (e) the biguanides (proguanıl), and () the diaminopyrimidines (pyrımethamine) No drug yet tested has any demonstrable effect on the sporozoite stage of the malaria parasite The cinchona alkaloids, aminoacndines, 4-amino- Andact Vact on 1 Y sites, but they have a powerful destructive action on the gametocytes of all species They also act on the secondary exoerythrocytic forms of Pmax, and it is in this respect that they have their greatest value They have an inhibitory effect on the pre erythrocytic forms of both P fala parum and P max but cannot be used for this purpose without risk of toucity The biguanides and the diaminopyrimidines are the only drugs which can be used with safety against the pre erythrocytic forms, and so far as is known they are fully effective only in falciparum infections They have no apparent action on the sexual forms of P falciparum in the peripheral blood, but both render these incapable of completing their development in the mosquito Antimalarial drugs may thus be placed in groups according to the stage of the life cycle on which they act, yiz (1) Drugs acting on pre erythrocytic forms (primary tissue schizontocides, causal prophylactics) For practical purposes, only proguanil and pyrimethamine come under this heading ·RATIONALE 27 (2) Drugs acting on asexual erythrocytic forms (blood schizontocides *) Whule most aatimalarial drugs have some action on these forms, the only ones which are of practical value for treatment of the clinical attack are chloroquine and related 4-amunoquinolines, mepacrine, and quinine. These drugs are effective suppressants of all species of human malaria parasites, and will effect radical cure in most cases of falciparum infection Proguanil and pyrimethamine are also effective suppressants, but are not sufficiently rapid in action for treatment of the clinical attack 10 a non immune subject (3) Drugs acimg on late exoerythrocy fic forms (secondary tissue schizontocides; anti-relapse drugs) The only compounds in this category known to be effective are the 8-aminoquinolines (pamaquide, primaquine) (4) Drugs acting on the sexual forms (gametocytocides) Pamaquine and probably other 8-aminoquinolines have a powerful destructive action rrin nan mand prar Onnine . af D the peripheral blood within a few days of treatment with these drugs. (5) Drugs acting on the sporogonic forms in the mosquito (sporontocides) Proguanil and pyrimethamine come under this heading Pharmacological consideranons An enormous volume of research has been devoted to studies of the pharmacology of antimalarial drugs, but there are still many gaps left in Inowledge of the subject, even in respect of the cinchona alkaloids For the effective treatment of the clinical attack, an adequate concentration of the drug in the red blood-cells, where the parasites reside, is essential The concentration attained in these cells by different drugs, however, shows wide variations That of quinine may be as low as one-eighth of the concentration in the plasma The low cell concentration attained by quinine as compared with other schizontocidal drugs is no doubt a reason why so much higher doses are required to produce the necessary effect Factors which aflect the attainment and maintenance of an adequate drug concentration in the red cells include the rate of absorption of the drug from the alimentary canal, competition for the drug between the red cells and various body constituents, such as the plasma proteins and tissue cells, and the rate at which the body degrades and excretes it Mepacſinc and the 4-aminoquinolines are rapidly absorbed and soon become localized in the tissues; degradation and excretion are slow and . This term has been suttested to distinguish these drugs from those actins on tissue bizonts, but they are full commonly designated khutontocides without qualification ·28 CHEMOTHERAPY OF MALARIA consequently these drugs persist in the body for long periods It is therefore necessary to administer a hugh intal, or loading dose, the red-cell con centration beiog kept at the required level thereafter by a lower mainten ance dosage It is interesting to note that the principle of giving a high loading dose of mepacrine, put forward by Shannon and his colleagues 21 in 1944, to enhance the therapeutic effectiveness of the drug, has found general acceptance among clinicians, the principle applies equally well in the use of chloroquine and other 4-aminoquinolines Quinine and the 8 aminoquinolines are rapidly absorbed, but plasma concentrations fall very rapidly in both instances It is therefore necessary to administer doses as high as possible and at frequent intervals, rather than a high loading dose followed by a lower maintenance dose Proguanil and pyrımethamine are active in very low concentrations, so 1 medanta Harran the tee pc the It is recogazed, however, that there are other factors besides blood concentration to be taken into consideration There is evidence, for instance, that proguanul and pamaquine, and probably also pyrimethamine, are not themselves active agents, but owe their efficacy mainly to a trans formation within the body into active metabolites Further details regard ing the pharmacological action of individual drugs are given in chapter 3 The varying response of different strains of the parasite Infections produced by strains of the same species of malaria parasite from different geographical areas may show wide variations in patho genicity, ability to develop in the mosquito host, relapse pattern, and immunological properties It is not surprising therefore, that differences in their response to the action of a particular drug are sometimes encountered More than 30 years ago, James and his colleagues observed that the amount of quinine required to control infections with Italian strains of P falciparum was several times as great as that needed for the management of infections with a strain of the same species of parasite from India In recent years, a number of similar instances have been recorded Infections with a New Guinea strain of P falciparum were successfully treated with proguanil by Fairley and his colleagues, whereas the same drug proved ineffective for radical cure of an infection with a strain of the same species of parasite imported to England from West Africa In prophylaxis, however, the drug proved equally effective against either strain Again, the Chesson strain of Pyzvax from New Guinea was found to be more refractory to both quinide and meparse than the McCoy strain from the southern United States of America ·RATIONALE 29 The Chesson strain, which is characterized by a senes of relapses occurring at short intervals following the primary attack, was also found by Coatdey and his colleagues to be much more refractory to ant-relapse treatment with primaquine than the long term relapsiog St Ebzabeth strain originally encountered in the United States of America The relapse rate in vivax malara is closely related to the manner in wluch the primary attack is treated Thus, with the Madagascar strain used in England for malaria therapy of neurosyphilis, if the patient is allowed to have a succession of 12 to 14 febrile paroxysms before treatment is begun, the relapse rate is about 50%, whereas, if an efficient blood schuzontocide is administered early in the attack, the rate may reach 90% or even bigher The immunity factor Many persons of the Negro race and occasional individuals of other races are bighly refractory to infection with vivas malaria This is an example of natural inmunity, as distinct from acquired immunity, which is the result of past or present infection Tolerance is an acquired immunity contingent on and conditioned by the continued presence of the parasite in the host A host with tolerance exhibits less reaction 10 a given quantum of infection, whereas one with natural immunity has an increased abilty to limit the quantum of infection developed Premunition is almost synonymous with tolerance, but has & greater connotation of immunity to superinfection with the same parasite la malana the immunity response is duected primarily against the asexual parasites in the blood, the tissue forms in the liver being completely protected from the cellulo bumoral immunity response An acquired immunity is most effective against infection with the same straja of parasite, but it may operate agarast beterologous strains to some degree The efficacy of an antimalarial drug cannot be properly assessed voul it bas been subjected to carefully controlled experimentation op subjects who are completely non immune Synerg2597 There are maay examples in chemotherapy where the action of a particular drug is enhanced or reinforced by the concurrent administration of another Sinton and his colleagues in India concluded that a combination of quinine with pamaquine was more effective for radical cure of vivax It is not serented however that tpeabc treatment of an overt malanal attack should be delayed on thus accoUDI ·30 CHEMOTHERAPY OF MALARIA infections than the action of either drug given separately As the result of these findings it has generally been accepted that quinine has a synergistic action on the 8 aminoquinolines or on their active derivatives enabliog them to destroy the late exoerythrocytic parasites more effectively and so prevent relapses Recent observations in the United States of America on avian and simian malaria have, however, thrown some doubt on this theory Coatney and his colleagues were unable to demonstrate synergism between quinine and the 8 aminoquinolines against gallınaceum infections, and Schmidt has been equally unsuccessful in experiments with P cjnomolgi, whose behaviour resembles that of the late relapsing strain of P vivax in so many respects These findings suggest that the two classes nol nas on the late tissue 1 ha enm nan of Korean vivax malaria among United States Military personnel by the routine administration of primaquine alone Greenberg and his co workers 13 have shown that proguanil and sutra diazine potentiate each other s action against P gallinaceum, and have demonstrated a synergism between proguanil and p aminobenzoic-acid antagonists which themselves act against gallinaceum infections Effect of drugs on plasmodium metabolism The first researches undertaken on the subject of the effect of drugs on plasmodium metabolism were those of Christophers & Fulton, who published results of thetr studies on the respiratory metabolism of P knowlesi in 1938 Intensive investigations on the biochemistry of erythrocytic stages of malaria parasites were continued during the second World War, par ticularly in the United States of America The metabolic activities of the parasites were found to resemble closely those of other orgaasms previously studied It was known that quinine has the property of inhibiting certain enzymes, and it seemed possible that the therapeutic effect of antimalarial drugs might be measu ed by their power to inhibit the respiration of malaria parasites The quantitative effect of various compounds on the oxygen uptake of malaria parasites was therefore investigated and it was found that the inhibitory action was in some degree parallel with the therapeutic effect Except in the case of certain naphthoquinones, however, the corre lation between inhibition of respiration of a malaria parasite and therapeutic efficiency of a drug was poor A number of other researches have been planned with the object of discovering some vulnerable link in the metabolic chain and in the growth ·RATIONALE 31 requirements of malaria parasites which might provide a clue to the syn thesis of more effective drugs From studies on the respiration and carbokydrate metabolism of malaria parasites it is possible to indicate certain points where these processes are deranged by antimalarial drugs There are also indications that certain vitamins, such as pamunobenzoic acid, pantothenic acid, and folic acid, if deficient or in excess, may influence antimalarial action Little is as yet knowa of the wtrogen requirements or muitrogen metabolism of malaria parasites, but it seems probable that while the parasite relies on the red cell for its protein metabolism, protein hydrolysis is I nked up with oudative processes Further studies are necessary bc ne possible action of antimalarial drugs on protein mu tabousm can to explained on a satisfactory basis ·CHAPTER 3 INDIVIDUAL COMPOUNDS IN COMMON USE Quinine Formula HOCHSCH ---CH, CH,0 CH, CH, CH, CH=CHCH=CH, quinine 6 methoxy (5 vinyl 2-quinuclidyl-4-quinol nemethanol Activity in human malaria (a) Sporozoites Inactive Quinine is herce (b) Primary exoerythrocytic forms useless for causal prophylaxis (c) Asexual erythrocytic forms A highly active blood schizontocide in all forms of human malaria, and hence an efficient drug for clinical cure With prolonged administration radical cure is often possible in falciparum infection, but seldom in vivax infection For suppression and suppressive cure quinine is less efficient than mepacrine or the better known 4 amino quinolines (d) Gametocytes Quinine has little gametocytocidal activity in fal ciparum malaria but is an effective gametocytocide in vivax and quartan malaria , for general gametocytocidal prophylaxis it is a poor drug (e) Secondary eroerythrocytic forms Inactive Quinine is thus a poor drug for radical cure in vivax malaria when used alone, when com bined, however, with certain of the 8 aminoquinolines a high cure rate is possible in vivax infection General The value of quinine in the treatment of malaria 15 attested by long experience Safe to use, consistent in action on the schizogonic blood forms, it may be used with confidence for the relief of symptoms in acute malaria, and, indeed, for the immediate treatment of severe • Sce Selected bibliography No 33 39 (page 100 -32 - ·COMPOUNDS NY CONVOY USE 33 NG + EFFECT ON ASEXUAL PARASITAEMIA IN ACUTE MALARIA OF THERAPEUTIC DOSES OF QUINIRE DIHYDROCHLORIDE XO BCD pono! cates 32 Meen count of sexual perearter per med peripheral blood to wcale) Amalaris B+ vt6Y Cfalciparum 845 w 070 We total 00 • Oas, oral doses of 1,000 mo or 2 000 mo per 100 5b (45 ko) body woight Days from beginning of teatment Unpublished data from Institute for Medical Research Federation of Malaya 1933-41 FIG 7 EFFECT ON FEVER IN ACUTE MALARIA OF THERAPEUTIC DOSES OF QUININE DIHYDROCHLORIDE .. ! 11.1 ta Moan matimum temperature A malarsa 8. Vivat Cfalciparum 293 845 Total 970 173) • Daiſy oras dozer of 1000 mg ac 3000 mg per 100 lb (23) body weight w Dart from beginning of treatment Vodoblashed data from taxutute for Medical Research Federation of Malaya 193345 ·34 CHEMOTHERAPY OF MALARIA falciparum infection, some authorities believe that quinine is unsurpassed by any of the new synthetic compounds its value as an adjuvant to the 8 aminoquinolines for the radical cure of vivas malaria is discussed in chapter 5 (page 82) Toxicity Serious toxic effects from the clinical use of quinine are very rare, but the drug has its own characteristic side effects Giddiness, deafness, ringing in the ears, tremors, and blurred vision may occur during the first few days of administration, particularly when the plasma level exceeds 12 mg per litre These symptoms, collectively known as cinchonism are seldom severe enough to interfere with treatment, they subside quickly when administration ceases and are never of serious import Given intra venously, quinine lowers the blood pressure Fatal collapse may occur as a result of intravenous injections administered too quickly in very severe Infection Idiosyncrasy to quinine occurs, but is rare Urticarial or erythematous rashes with intense itching, subcutaneous or submucous haemorrhages, oedema of the eyelids, mucous membranes, or lungs, and even collapse, have been known to follow a single dose Excessive dosage may cause temporary blindness or deafness, possibly with permanent impairment of sight or hearing Recovery from a single oral dose of 10 000 mg (150 grains) and death from a single dose of 16,000 mg (240 grains) have been reported Contraindications There are few contraindications to the use of quinine in the treatment of malaria Patients with an idiosyncrasy to quinine must obviously be treated with some other drug, and a history or threat of blackwater fever is a clear in 1on for withholding quinine in favour of one of the synthetic compounds The controversial question of quinine in pregnancy has lost its urgency with the modern developments in therapy, untreated malaria is more likely to induce abortion than is quinine, but most physicians will play for safety by using some alternative drug Absorption, elimination, plasma concentration Quinine passes through the stomach unchanged and is quickly and almost completely absorbed from the upper intestinal tract to circulate as a base The rate of absorption is not greatly affected by the route of administration, and the drug appears in the urine in an hour or less whether ·COMPOUNDS IN COMMON USE 35 given by the mouth or by intramuscular or intravenous injection Quinine is quickly destroyed by the tissues or excreted unchanged in the urine, and little remains in the body 48 hours after the last dose Peak concedtrations in the plasma are reached from one to three hours after adminis tration by mouth, the amount in the red cells being about one fifth of that in the plasma A mean plasma concentration of 25 mg per Istre is FIG : CONCENTRATION OF QUININE (GROUP MEANS) IN PLASMA DURING TREATMENT WITH 500 mg 1 000 mg AND 2 000 mg OF QUININE SULFATE DAILY FOR SIX DAYS VO 100 500 Quinine (mg) per I tre of plasma (log oca e) 10 a) HM Days from baglaning of treatment X and of treatment After Contney et al probably necessary to reduce parasitaemia in acute vivax malaria, and me marr . species the effective plasma level may depend on the strain of parasite Dosage and route of administration Sec chapter 5 ·36 CHEMOTHERAPY OF MALARIA Test for detection in body fluids Quinine may be detected in the urine by Mayer's test Mayer's reagent Mercuric chloride 6,800 mg Potassium iodide 24,900 mg Distilled water 500 ml Procedure (a) Add clear urine to each of two test tubes (cloudy urine should be shaken with kieselguhr and filtered) (6) To one tube add a few drops of acetic acid (c) To both tubes add a few drops of the reagent Interpretation (a) If both tubes remain clear, the test is negative (b) If both tubes show turbidity, the presence of quinine is probable Confirm by demonstrating the disappearance of turbidity on boiling the acidified urine in tube 2 Should the urine remain turbid the pre sence of albumin is probable Filter hot to remove the albumin quinine precipitates as the filtrate cools (c) If the acid tube alone shows turbidity, the presence of quinine, albumin, or both may be inferred to identify quinine, boil and filter hot, as in (6) Precipitates due to quinine and albumin appear almost immediately Sometimes turbidity develops slowly in the acid tube, when the presence both of quinine and albumin can be excluded Precipitates which appear late may be ignored for the purpose of the test Cinchona mixtures Muxtures of cinchona alkaloids have one advantage over quinine they are cheaper Their activity in the treatment of malaria is essentially the same they cannot be used for injection and they are rather more likely to cause nausea or vomiting According to the definition of the Malaria Commission of the League of Nations, totaquina (totaquine) is a mixture containing not less than 70% of crystallizable cinchona alkaloid, of which not less than 15% 18 quinine, nor should it contain more than 20% of amorphous alkaloids It should not contain more than 5% of water, and the mineral ash-content should not exceed 5%, preferably 3% ·COMPOUNDS IN CONVOY USE 37 Salts in common use Sulfate, bisulfate, hydrochlonde, and dihydrochloride, prescribed either in solution or in tablets or capsules Physical data regarding salts See Annex 3 Primaquine and Other 8-aminoquinolines * Formulae CH,0 CH, CH NICH(CH),N CH, CH, pamaquine 8-{4-diethylamino 1 methylbutylamino)-6-methoxyquinoline NHCH(CH),NIIR CH, primaquipe 8-(4-anuno 1 methyl butylamino) 6-methoxyquinoline ActMy in human malaria (C) Sporozoites Probably inactive (b) Primary exocrythrocytic forms Active against these forms of P max and P falciparum, particularly the latter Activity against these forms of P malariae is not known (C) Asexual blood forms Active against the aserual blood forms of P max and P falciparum, but only at a dosage dangerously high for routine use (d) Gametocytes Highly active against the gametocytes of all species of human malaria parasite (e) Secondary exoerythrocytic forms Highly active Radical cure of vivax malana is usually produced whether the drug 15 administered during a relapse or during latency Data on similar presumed stages of quartan mataria are not available General The discovery in pamaquine of a drug which could act . • Sec Selected bibliography No 40-53 (page 107) ·38 CHEMOTHERAPY OF BLALARIA asexual blood parasites, like that of the other 8-aminoquinolines, is effective only at dangerously hugh dosage has, however, precluded its use for treatment of the acute attack, though it has been used extensively for the prevention of relapse in vivax malaria, for which until recently it was the only drug available It seems likely that primaquine, with its lower toxicity and greater effectiveness against fixed tissue stages of the parasite, will eventually supersede pamaquine for the radical cure of relapsing malana Studies are now in progress to investigate its effectiveness for prophylactic suppression Toxicity At the recommended dosage, no symptoms of toxicity are likely When include anorexia, nausea, ad cramps, the passage of chest pain, and weakness In addition, there may be striking effects on the formed elements of the blood and the bone marrow, marked by leukopenia, anaemia, methaemoglobinaemia, and suppression of myeloid activity, with lesser effects on the heart and circulation These manifestations disappear when the drug is withdrawn The tendency for haemolytic reactions is increased in all the dark-skinned races Contraindications Because the tendency for methaemoglobinaemia and granulocytic neutropenia, and probably for acute haemolytic anaemia, is potentiated by mepacrine, none of the 8 aminoquinolines should be administered concurrently with, or immediately following, treatment with mepacrine Absorption, elimination All the 8-aminoquinolines are rapidly absorbed, elimination is accomplished entirely within 24 hours through metabolic conversions and excretion of the degradation products in the urine, only a very small amount Is fixed in the tissues Dosage and route of administration See chapter 5 Tests for detection in body fluids Because of the rapidity of elimination and of the low dosages needed to effect cure, tests for plasma concentration of the s-aminoquinolines are neither needed nor recommended ·COMPOUNDS IN COMION USE 39 Saits in common use Primaquine diphosphate, pamaquine naphthoate and monohydrocblonde Physical data regarding salts See Annex 3 Synonyms See Annex 4 Mepacrine Formula CH, CH NHCH(CHDN CH CH,0- C1 mepacrine 6-chloro 2 methoxy 9 (4-diethylamino-1 methylbutylamino)acridae Activity in human malaria (a) Sporozoites Probably inactive (6) Primary exoerythrocytic forms Inactive against these forms of all species of malaria parasite (c) Asexual blood forms Highly active against the asexual blood forms of all species Will produce clinical cure of all types of human malaria and radical cure of falciparum infection Mepacrine is an excellent suppressive agent against all species of human malaria parasite and in falciparum infection it can effect suppressive cure Morphological changes, marked by a distinctive clumping of the pigment, are characteristic of its action (d) Gametocytes Mepacrine acts as a gametocytocidal agent against P war and P malariae, it is ineffecuve aganst the gametocytes of Pfalciparum (e) Secondary exoerythrocytic forms Inactive Mepacnne will not effect radical or suppressive cure of vivax malaria The effect on similar presumed stages of quartan malana is unknown • Sea Sclected b bbograpby, No 5471 (a) (page 109) ·40 CHEMOTHERAPY OF MALARIA General Mepacrine is superior to quinine in that (1) it has greater antimalarial activity against asexual blood parasites both as a suppressant and as a therapeutic agent, particularly against certain strains of P falciparum , (2) its use is attended by a lower incidence of blackwater fever, (3) it is a synthetic product and therefore supply is not affected by vicissitudes of nature or by geographical location Even with these advantages the drug has certain limitations (1) it dyes the skin and conjunctivae yellow and occasionally causes alarming, though transient, mental disturbances (see below), (u) it must be given daily, or not less than twice weekly, for complete suppression of all types of malaria , (111) adequate management of acute malarial attacks in non immune subjects may require seven days of drug administration Toxicity When administered initially at the recommended dosage, gastrointestinal distress may appear in the form of abdominal cramps, nausea, vomiting, and diarrhoea, but these symptoms disappear with continued administration of the drug Mental symptoms varying from pronounced depression to extreme excitement or even mania may occasionally occur, but these disappear when the drug is withdrawn Under humid tropical conditions cutaneous lesions (atypical lichen planus) may develop into a generalized exfoliating dermatitis Aplastic anaemia has also been attr buted to prolonged ingestion of mepacrine Contraindications Apart from individual idiosyncrasy, syphilis affecting the central nervous system is the only contraindication to the use of mepacrine in the treatment of malaria 714 Convulsive seizures have been recorded in such patients following its administration, and it is advisable, therefore, to use some other drug for the management of malaria in such cases Absorption, elimination, plasma concentration Absorption of the drug is rapid, elimination is slow, due to its pro nounced affinity for the organs and tissues, where the concentration may reach several hundred times that found in the plasma Only about 10% or less as eliminated in the urine daily, with the result that from three to four weeks are required for concentrations to drop below non effective levels Peak concentrations of 50 60 ug per litre in plasma are attained IVhen dosts plasma ·COMPOUNDS IN COMMON USE 41 Dosage and route of administration See chapter 5 FIG 4 INDIVIDUAL CONCENTRATIONS AND GROUP MEANS OF MEPACRINE IN PLASMA DURING AND FOLLOWING G-DAY THERAPEUTIC COURSES TOO Mepacrine (vo) per litre of plasma (og scale) TO 3 20 3 Days from beginning of treatment Xend of treatment mean concentration ... Individual concentration • 200 mg of wepacrine hyd ochloride times cally the frst day followed by 100 mg of mopacrine hydrochloride 4 times daily for 5 days Aller Cooper et al Tests for estimation in body fluids (1) For estimation of mepacrine in body fluds, a single extraction procedure has been developed by Brodie et al 56 Reagents (@) 01N NAOH (6) Heptane a technical grade is purified by successive washings with 1 N NaOH, IN HC1, and water (c) Iso-amyl alcohol, reagent grade (d) Trichloroacetic acid solution 2,500 mg of the acid are dissolved in 100 ml of ethylene dichloride ·42 CHEMOTHERAPY OF MALARIA Procedure (a) Add 1 5 ml of biological fluid and an equal volume of O IN NaOH to 15 ml of heptane in a 60-mi glass stoppered bottle (b) Shake for 30 minutes Allow the phases to separate, centr fuging if necessary (©) Add 0 5 ml of iso amyl alcohol and mix with the heptane phase so as not to disturb the aqueous phase (d) Transfer 10 ml of the heptane phase material to a fluorometer tube containing 1 ml of trichloroacetic acid solution A blank of the heptane, iso amyl alcohol and the trichloroacetic acid solution is used for the setting of the fluorometer If a reagent blank-namely, with water substituted for plasma or urine---is run, the reading should be the same as the blank set up with pure chemicals Standards are prepared by extracting known amounts of Depacrine 10 the same manner as the biological sample The computation of mepacrine concentration is by direct proportion (2) A modification of the test, devised by Wats & Ghosh,7l has been found useful in Malaya (a) To 10 ml of urine in a test tube add 1 ml of saturated solution of potassium carbonate (b) To the alkalınızed urine add 0 25 ml of amyl alcohol (c) Thoroughly shake and put aside for a few minutes to allow the alcohol to separate (d) Examine by ultra violet light for yellow fluorescence in the alcohol layer The alcohol layer contains most of the mepacrine When examined by ultra violet light, the extracted mepacrine fluoresces a vivid yellow The test is extremely sensitive and reveals the presence of mepacrine in a dilution approaching one part in two and a half million Salts in common use Dihydrochloride dehydrate, methane sulfonate Physical data regarding salts See Annex 3 Synonyms See Annex 4 ·COMPOUNDS N 00100OY USE Formuloe Chloroquine and Other 4-amiaoqainolines * CH, NHCH(CH), CH, AN chloroquine 7-chloro-4-(4 dietbylamino amodiaquine 7-chloro-(3-diethylamino I methylbutylamino)quroline methyl-4-hydroxyandisolquinoline Activity in human malaria (a) Sporozoites Probably inactive (6) Primary exoerythrocytic forms Inactive in all types of malara (c) Asexual blood forms Chloroquine and amodraquine are highly effective against the asexual blood forms of all species of malaria parasite They will produce chincal cure of all types of human malaria and radical cure of falciparum rafesuon They are excellent suppressive agents against all species, such administration continued for from three to four weeks, results in suppressive cure of falciparum malaria Morphological changes, marked by distinctive clumprog of pigmeat, are characteristic of their action (d) Gametocytes Chloroquine and amodiaquine act as gametocyfocidal agests against P vivax and P malarige , they are ineffective against the gametocytes of P falciparum (e) Secondary exocrythrocytic parasites Inactive They will not produce radical or suppressive cure of vivax malarsa The effect on similar presumed stages of quartan malania is unknown General Chloroquine and amodiaqume are superior to mepacrine in that (t) they have greater activity as suppressive and therapeulic agents, fever is usually absent after 24 hours with climination of patent parasitaemia in from 48 to 72 hours, (2) less frequent administration is required for effective results, (3) periods of latency are longer , (4) chere is less lissuc reaction following intramuscular admnistration, (5) tbey do not stase the skin or conjuctivae Sontoquoc and other 4 amidoquinolines kutberto tested have proved less active than chloroquine or amodiaquae as regards antimalarial properties • Sce Selected bbostaphy, No 72-88 (pate 109) ·44 CHEMOTHERAPY OF MALARIA Toxicity Toxicity is extremely low at doses ordinanly employed for therapy or suppression and although headache, pruritus, and blurring of vision have been reported following therapeutic doses, these synaptoms usually disa appear shortly after administration has been discontinued Contraindications No contraindications have been reported to date Absorption, elimination, plasma concentration Absorption from the gastro intestinal tract is rapid and almost complete These drugs are extensively localized in the tissues, from where they are metabolized and excreted slowly On an equal dose basis, concentrations of chloroquine in the plasma are from 10 to 20 times higher and persist longer than is the case with mepacrine, concentrations of chloroquiac in "the plasma tend to be higher than with other 4 aminoquinolides Under accepted regimens of therapy employlag loading doses, effective chloroquide concentrations are reached within from two to three hours When the drug is given intramuscularly, therapeutically effective plasma chloroquine concentrations are reached in less than 15 minutes FIG 5 INDIVIDUAL CONCENTRATIONS AND GROUP MEANS OF CHLOROQUINE N PLASMA DURING AND FOLLOWING GRAY THERAPEUTIC COURSES 1000 1000 fod Chloroquine (ug) per litre of plasma (los scale) 2 0 1 we Days from beginning of treatment Xe end ot treatment mean concentration ***... Individual concentration * 200 mg of chloroquine (base) 4 times daily the hrst day followed by 100 mg of chloroquine (bate) 4 times dally for 5 days After Coatacy et 22" ·COBIPOUNDS IN COMMON USE Dosage and route of administration See chapter 5 45 Test for estimation in body fluds A double extraction procedure for the estimation of chloroquine in body fluids has been worked out by Brodie et al 58 Reagents (a) Standard solution of chloroquine, 100 mg per Intre 161 mg of the diphosphate salt are dissolved in 1 litre of O IN HC! This solution is stable when stored in the refrigerator Working standards are prepared daily by dilution with 0 IN HCI (b) O IN NAOH (c) Heptanc a technical grade of heptade is purified by successive washings with 1 N NaOH, I N HCI, and water (d) Absolute ethanol (e) 01 N HCI V OSN NaOH I ml should be neutralized by 5 ml of the above 01 NHCI (8) Buffer reagent, pH 95 S volumes of 06 M bonic acid in 06 M KCl are added to 3 2 volumes of 06 N NaOH When diluted as described in the procedure and after the addition of the cysteine reagent, the resulting pH should be 9 4-96 Thus pH should be checked by direct measurement (1) 5% cysteine reagent 1 000 mg of cysteine hydrochloride is dissolved in 20 ml of water This solution is neutralized by the addition of 0 8 ml of 10 N NaOH This reagent should be made fresh daily and neutralized just before use Procedure (a) Add 1 10 ml of biological sample (containing up to i ug of chloroquine) and an equal volume of O IN NaOH to 30 ml heptane in a 60-mi glass stoppered bottle (6) Shake for 30 minutes Allow the phases to separate, centri fuging if necessary (c) Add 8 drops of cthanol and mix with the heptane phase so as Dot to disturb the aqueous phase (d) Transfer the heptane to a 125-ml glass stoppered bottle, add about twice the volume of OIN NaOH and shake for 5 minutes (e) After settling add 8 drops of ethanol to the heptane and mux as before Remove the aqucous phase by aspiration ·46 CHEMOTHERAPY OF MALARIA (Repeat the washing with 01 N NaOH, add 5 drops of ethanol, and transfer 20 ml of the heptane to a 60-ml glass stoppered bottle containing 6 ml of 0 1 N HCI (8) Shake for 3 minutes and then centrifuge for 2 minutes (h) Transfer 5 ml of the acid phase to a fluorometer tube containing 10 ml of 0 5 N NaOH and 15 ml of buffer reagent Add 05 ml of cysteine reagent and mix b) A reagent blank, with water substituted for plasma or urine, is run through the same procedure Standards are prepared by adding known amounts of the drug in 5 ml of 0 1 N HCl to 1 ml of 0 5 N NaOH and 1 5 ml of buffer in fluorometer tubes 05 ml of cysteine reagent is added to each tube A "dummy", consisting of acid, alkalı, buffer, and cysteine reagent, is used for the blank setting of the fluorometer After 30 minutes all tubes are irradiated with ultra-violet light, as described below The intensity of fluorescence of the irradiated samples is determined in the Coleman photofluorometer, using Coleman B,S and Coleman PC filters The sensitivity of the instrument is set by quinine, since the intadiated standards may slowly lose their fluorescence on frequent exposure to the ultra-violet light of the fluorometer Irradiation of the 4-aminoquinolines is effected in a simply constructed irradiator, using an H-4 mercury arc lamp as the light source The samples are placed in a circular rack surrounding the lamp so that they are equidistant from the lamp, and are irradiated for 3 hours A fan is used for keeping the temperature of the solutions below 35ºC during irradiation Salts in common use Chloroquine diphosphate and dihydrochloride, amodiaquine dihydrochloride dihydrate Physical data regarding salts See Annex 3 Synonyms See Annex 4 Proguanil * Formula NH NH -N-C-N-C-NHCH(CH) proguanu N, P(chlorophenyl) Ng-isopropyl biguanude * See Selected bibliography, No 89 113 (page 110) ·COMPOUNDS IN COMMON USE 47 Activity in human malaria (a) Sporozoites Probably inactive (6) Primary exoerythrocytic forms Proguanil is highly active against the primary exoerythrocytic forms of P falciparum and has a fleeting inhibitory action on those of P pivax, its action on the presumed primary cxoerythrocytic forms of P malariae is unknown It is thus a powerful drug for causal prophylaxis in falciparum malaria (c) Asexual blood forms Active against the asexual blood forms of all species of human malaria parasite It will achieve clinical cure in all forms of malaria, with radical cure in most falciparum infections, but the clinical response is slow, and its use for the treatment of an acute malarial attack is not recommended It is a good suppressive of all forms of malaria, often with suppressive cure in falciparum infection It appears to act by inhibiting nuclear division FIG & PARASITAEMIA IN 268 CASES OF ACUTE FALCIPARUM MALARIA TREATED IN MALAYA WITH PROGUARIL ILLUSTRATING A DEVELOPING RESISTANCE IN THE SCHIZOGONIC BLOOD FORMS 100000 000: Moon count of asexual pa asites per mm' per pheral blood (og scale) pa Days from beg aning of treatment cares progvanl! Ingle dote 100 mg (1947-8) 20 250 mg or 300 mg (1943) 40 70 daily s mg Catandard courtej (1990-11 250 mg or 300 mg (1949) is total 968 Data from Malang Research Divison Costitute for Medical Research Federation of Malaya 1946-1 SAUR ·46 CHEMOTHERAPY OF MALARIA Repeat the washing with 0 IN NaOH, add 5 drops of ethanol, and transfer 20 ml of the heptane to a 60-ml glass-stoppered bottle containing 6 ml of 0 1 N HCI (g) Shake for 3 minutes and then centrifuge for 2 minutes (1) Transfer 5 ml of the acid phase to a fluorometer tube containing 10 ml of 0 5 N NaOH and 15 ml of buffer reagent Add 05 ml of cysteine reagent and mix (1) A reagent blank, with water substituted for plasma or urine, is run through the same procedure Standards are prepared by adding known amounts of the drug in 5 ml of 0 1 N HCl to 1 ml of 0 5 N NaOH and 1 5 ml of buffer in fluorometer tubes 05 ml of cysteine reagent is added to each tube A "dummy" consisting of acid, alkalı, buffer, and cysteine reagent, is used for the blank setting of the fluorometer After 30 minutes all tubes are irradiated with ultra-violet light, as described below The intensity of fluorescence of the irradiated samples is determined in the Coleman photofluorometer, using Coleman Bis and Coleman PC filters The sensitivity of the instrument is set by quinine, since the irra diated standards may slowly lose their fluorescence on frequent exposure to the ultra-violet light of the fluorometer Irradiation of the 4 aminoquinolines is effected in a simply constructed irradiator, using an H-4 mercury arc-lamp as the light source The samples are placed in a circular rack surrounding the lamp so that they are equidistant from the lamp, and are uradiated for 3 hours A fan is used for keeping the temperature of the solutions below 35°C during irradiation Salis in common use Chloroquine diphosphate and dihydrochloride, amodiaquine dihydrochloride dihydrate Physical data regarding salts See Annex 3 Synonyms See Annex 4 Formula Proguanil * NH NH н II н. -N-&-N-~-NHCH(CH), proguanil Nip(-chlorophenyl)-N, isopropyl biguanide See Selected bibliography No 89 113 (page 110) ·COMPOUNDS IN COMION USE Atuty in human malaria (0) Sporozoites Probably inactive (6) Primary croerythrocytic forms Proguanıl is hughly active against the primary exoerythrocytic forms of P falciparum and has a fleeung abbitory action on those of P var, its action on the presumed primary croerytrocytic forms of P malariae is unknown It is tous a powerful drug for causal prophylaxis in falciparum malarsa (c) Asexual blood forms Active against the asexual blood forms of al species of human malana parasite it will achieve clinical cure m all forms of malarsa, with radical cure is most falciparum infections, but the clinical response is slow, and its use for the treatment of an acute malarial attack is not recommended It 13 a good suppressise of all forms of malana, often with suppressive cute in falciparum infection it appears to act by abibiting ouclear division FIC PARASITREMIA FN 288 CASES OF ACUTE FALCIPARUM MALARIA TREATED IN MALAYA WITH PROGUANIL SLLUSTRATING A DEVELOPING RESISTANCE IN THE SCHIZOGONIC BLOOD FORMS Kood Wond 1000 Mean count of sexual paraphes por mm peripheral bloed (lag scale) Days from beginning of treatment tases proguani ing done 100 mg (1947-) 76 250 mg or 300 mg ste) 250 mg or 300 mg (1949) tally so mo alandard courte) (1950-1} 1 total 23 Data from Alalans Research Dinson. Institute for Medical Rescarth Federation Malaya 1946-7 ·her 48 CHEMOTHERAPY OF MALARIA FIG, 7 FEVER IN 913 CASES OF ACUTE FALCIPARUM MALARIA TREATED IN MALAYA WITH PROGUANIL OR QUININE 102389 No 1 101 39 3 Mean maximum temperature 100378 99 V2 9367 too Days from beginning of treatment Toua IT011 cases 26 40 74 128 645 913 total Data from Malaria Research Division Institute for Medical Research Federation of Malaya 1946 7 (d) Gametocytes Proguanil has little apparent effect on the produc. tion, numbers, or morphology of the gametocytes of P falciparum, but in appropriate doses the drug inhibits the later development of sporogonic forms in the mosquito Mosquitos fed on gametocyte carriers receiving therapeutic doses of proguanil do not become infective--an inhibitory effect on sporogony which lasts for varying periods up to ten days after the last dose, depending on the total quantity administered Sporogony in P max is similarly affected Proguanil is thus a valuable drug for sporontocidal proph, laxis (e) Secondary exoerythrocytic forms Probably inactive, and hence a poor drug for radical or suppressive cure in vivax malaria Its effect on the presumed secondary exoerythrocytic forms of P malariae is unknown ·49 COMPOUNDS IN COMMON USB ) General The outstanding virtues of proguan! are its extremely low toxicity, wide range of action, and relatively low cost It is highly active as a causal prophylactic in falciparum malaria, is a good general suppressive, has a marked inhibitory effect on the transmission of malana by mosquitos, but is not sufficiently rapid in action for treatment of the acute attack 10 non immune subjects Its greatest drawback, a tendency to provoke reststance, is discussed in chapter 4 (page 59) Toxicity At the therapeutic dosage the toxicity of proguanil is very low, abdominal discomfort, loss of appetite, vomiting, and diarrhoea may be caused by doses of the order of 1,000 mg daily, more rarely, haematuria may be produced by such gross over dosage Contraindications No contraindications are known other than the presence in the area of strains resistant either to proguanil or pynmethamine (see chapter 4, page 64) Absorption, elimination, plasma concentration Absorption is rapid, elimination is fairly slow, mainly in the urine, in which the drug may be detected for several days after the last dose About 40% is excreted in the urine and faeces, some of the remainder is converted into an active metabolite Peak concentrations in plasma are attained about four hours after oral administration The concentration in the red cells is from four to eight times greater than in the plasma Plasma levels fall below the level of accurate estimation within a week, even after heavy and prolonged dosage Dosage and route of administration See chapter 5 Test for estimation in body fluids A simple test for proguanil in the uriae has been devised by Gage & Roseto Reagents (a) Copper sulfate analyucal reagent (AR), 500 mg, and ammonium chloride AR, 1,330 mg, 10 100 ml of distilled water

·50
CHEMOTHERAPY OF MALARIA
FIG & CONCENTRATION OF PROGUANIL (GROUP MEANS) IN PLASMA
DURING ORAL TREATMENT WITH 100 mg AND 1,000 mg DAILY
40
1000
200
Proguanil (vo) per litre of plasma
TO
100
Days after beginning of treatment
X – end of treatment
After Adams et al **
(6) Sodium diethyldıthiocarbamate 0 1% aqueous solution (the
solution does not keep for more than a fortnight)
c) 1 N NaOH
(d) Benzene the commercial grade redistilled is satisfactory
Procedure
(a) Mix 2 ml of urine, 1 ml of copper reagent, and 1 ml of the
caustic soda solution 10 a stoppered tube and allow to stand for a few
minutes
(6) Add 5 ml of benzene and shake for 2 minutes Decant or
Pipette off the benzene into a second tube, wash with 1 ml of water,
and transfer to a third tube
(c) Shake with 1 ml of sodium diethyldithiocarbamate solution for
1 minute
The intensity of the golden yellow colour is a measure of the amount
of proguanıl
Salts in common use
Monohydrochlonde, acetate, lactate

·COMPOUNDS NOVVOY USE Physical data regarding salts Sce Annex 3 51 Synonyms Sce Annex 4 Formula Pyrimethamine N NH, HAN- NS с̧н, pynteethamue 24-diamino-5 p-chlorophenyl-6-ethylpynmedine Activity in human malaria (a) Sporozoites Probably snactive (6) Primary crocrythrocytic forms It is thought that pyrimethamine may have some effect against these forms, but the degree of such action has not yet been defined (c) Asexual blood forms Active against these forms in all types of malaria, producing clinical cure in all and radical cure in most cases of P falciparum infecuon Its action is, however slow, and it is therefore pot recommended for treatment of the acute attack Dose for dose, pyrı methamine is the most powerful suppressie agent known suppressie cure is achieved against P falciparum infection and sometimes agaiast P mar Like proguanil it appears to act by inhibitiog nuclear division FIG. EFFECT ON PARASITE RATE IN MAN OF WEEKLY S-mg DOSES OF PYRIMETHAMINE Parasiterale 05 60 picture o Data from Hinske & Lips after Goodwa 1951 • See Selected babl agraphy No 114-130 (2p 111) ·$2 CHEMOTHERAPY OF MALARIA FIG 10 EFFECT ON SPOROZOITE RATE IN MOSQUITOS OF WEEKLY 25-mg DOSES OF PYRIMETHAMINE untud control on bymethane dre 1951 1932 omg om Data from Vincke & Lids after Goodwin 131 (d) Gametocytes There is no apparent effect on the production, number, or morphology of gametocytes, but the action of the drug inhibits subsequent sporogony in the mosquito, resulting in sporontocidal prophylax's (e) Secondary exoerythrocytic forms Active against certain strains of P vivax, although the exact conditions necessary for such action, in dosage and time, are not clearly defined Its effect against similar presumed stages of P malariae is unknown ) General Pyrimethamine is a potent drug of extraordinary effectiveness against erythrocyuc parasites Iis chief characteristics are (i) small weekly doses can effect complete suppression of quartan malaria and suppressive cure of vivax and falciparum malaria , (2) by inhubiting sporogony at prevents transmission of malana by mosquitos, (3) it is tasteless and therefore easy to administer to children, (4) it is relatively inexpensive Its limitations are (1) that its action is too slow to warrant its use for treatment of an acute malarial attack in a non immune subject , (u) drugresistance may develop in the field, if it is administered in insufficient dosage (see chapter 4) Toxicity At the recommended dosage toxicity is very low, long term administration of 25 mg daily may result 10 a megaloblastic type of anaemia, but remission is rapid when tåe drug is discontinued Contraindications No contraindications are known other than the presence in the area of strains resistant either to pyrimethamine or to proguanil (see chapter 4, page 64) ·COMPOUNDS IN COMIOY USE 53 Absorption, elimination, plasma concentration Studies in thesus monkeys utilizing doses above those recommended for man have led to the following conclusions Absorption of pyrimethamioc from the intestinal tract is relatively slow but essentially complete It is localized to a moderate degree in the fung, liver, Kidney, and spleen About 20% of the drug administered can be recovered in the urine, this represents metabolic products and unchanged drug The drug does not ordinanly accumulate in the plasma Peak concentrations following oral admin.stration are reached an approximately two hours Dosage and route of administration See chapter 5 Test for estimation in body fluids At recommended dosages, plasma levels are too low for accurate determination, details of the test, therefore, are not included here Those interested in the methyl orange test, modified for determining pyri. methamine concentrauon in body fluids, are referred 10 Schmidt, Hughes & Schmidt 125 Salts in common use Pyrimethamide is prescribed as base, not as a salt Synonyms See Annex 4 ·CHAPTER 4 DRUG-RESISTANCE IN MALARIA * 1 46 One of the limiting hazarate in the nonflexible response seeks to destroy parasite, be it virus, bacterium, protozoon, or metazoon, must adapt or perish The drug in the host tissues may impose on the parasite metabolic demands which are beyond its capacity for individual or group adaptation: the parasite is then " drug-sensitive and will remain sensitive The parasite, on the other hand, may adapt itself to the new chemical environ. ment, and to the extent of its successful adaptation it will become drug-resistant Drug resistance from the adaptation of living organisms to substances which normally destroy them or prevent their growth has been known for many years Kossiakoff,152 in 1887, showed that bacteria could be "trained" to grow in media containing antiseptics, and two years later Massart 155 proved that flagellates could be adapted to resist concentrations of sodium chloride normally toxic Renewed interest in this interest ing phenomenon was aroused with the discovery by Ehrlich, in 1908, that trypanosomes exposed to sublethal doses of trypanosomocidal drugs become resistant, and the later studies of Warrington Yorke and his colleagues brought the problem of drug-resistant trypanosomiasis to a sharp focus, but the wider implications of this work were not fully realized, and only with the discovery of acquired bacterial resistance to the sulfonamides, penicillin, and streptomycin, has drug-resistance made any serious impact on treatment Today, it seems, drug-resistance may be the rising price that has to be paid for the quickening tempo of chemotherapeutic advance Significant drug-resistance in malaria is a recent phenomenon No important antimalarial drug used before the end of the second World War was known to induce serious resistance Quinine, pamaquine, and mepacrine, the mainstays of malaria therapy, had never given serious cause for anxiety on this score, and it seemed that the malaria parasite might lack the capacity for adaptation which certain bacteria were then beginning to show towards the sulfonamides and penicillin But the discovery, in 1947, of acquired resistance to proguanil in the avian parasite P. gallinaceum • See Selected bibliography, No 131-173 (page 114) - 54 - ·DRUG-RESISTANCE 55 sounded a note of warning 132 158 The asexual blood forms of this species could be “trained "—if we may use the word "trained" with no implication of the mechanism involved-to resist high doses, and the resistance was stable enough to survive passage through mosquitos In quick succession other species of Plasmodium, including P falciparum and P mar infecting man, were shown to share this capacity for adaptation to proguanil, and for the first time drug resistance in malaria appeared as a significant clinical problem Definitions The expression “drug resistant malaria" has a deceptive simplicity Malaria parasites may be said to "resist " when exposure to a drug in the tissues of the host leaves at least some of them unharmed They resist small doses of quisine they resist many drugs which are lethal to other minute forms of life but have no interest as remedies for malaria Resistance in this wide sense has little relevance to the clinical problems of drug resistant malaria, and in this discussion we shall consider it only in relation to drugs which, administered to the vertebrate host 10 adequate and safe doses, normally destroy or contribute to the destruction of malaria parasites at some stage or other in their life-cycle Resistance within the limits of dosage tolerated safely by the host may be absolute, or it may be relative to a normal sensitivity Sporozoites are completely refractory to the largest doses of quinine the host will stand, within this limit their resistance is absolute Resistance in particular geographical strains, on the other hand is relative to the general sensitivity of other strains, and acquired resistance is relative to the initial sensitivity of the species before there has been significant drug contact Resistance to a drug is conveniently expressed in terms of the dosage administered with safety to the host If, for example, the lowest lethal concentration for a parasite is attained on first exposure by a host dosage of 5 mg, but later only by 500 mg, the parasite is said to have acquired a bundredfold resistance An arbitrary limit to reststance is reached when the dose which is lethal to the parasite is no longer safe for the host Natural resistance within a species All malaria remedies are selective in their action The parasite is not uniformly sensitive to drugs throughout its life-cycle, and at particular stages it may show a high degree of natural resistance Sporozoites, possibly from their flecting exposure in the buman host, seem to resist all known drugs, and to most drugs the tissue forms are equally refractory With few exceptions, the asetual blood forms in all species are scositive ·56 CHEMOTHERAPY OF MALARIA to all the accepted malaria remedies, while the gametocytes show marked specific differences in this respect Table I illustrates this natural resistance within a species TABLET NATURAL DRUG RESISTANCE AT VARIOUS STAGES IN THE LIFE CYCLE OF PFALCIPARUM AND PYIVAX Pfalciparum P vivax & poro zoltes tissue forms blood forms game (asexua) focytes sporo zoltes قعودا forms blood forma (asexua!) game tocytes Quinine R R R R R R R R R R R R R R R Mepacrine Chloroquine Pamaquine Proguanit Pyrimethamine R R R R R R R R - resistant Thus selective resistance within a species is a fixed character in no way related to earlier exposure to a drug it poses no novel problem and its acceptance has long been implicit in the planning of malaria therapy Resistance in geographical strains Malarial infections from different parts of the world do not always respond equally well to the same treatment, and it seems that geographical strains of the same species of parasite sometimes differ in their sensitivity to particular drugs The reason for these strain differences is not always clear They may possibly express a natural variation related to geographical isolation, but the influence of previous contact with drugs can seldom be excluded Resistance acquired by previous drug contact A high degree of drug resistance in a species normally sensitive is probably always an adaptive change related to previous exposure A thousandfold resistance to proguanil has been produced experimentally in the blood forms of P vivax 1 Malayan strains of P falciparum, sensitive za 1947 to a single dose of 100 mg of proguanil, were resistant to many times this dose two years later " The asexual blood cycle of the monkey ·DRUG-RESISTANCE 57 parasile, P cynomolgi, is naturally sensitive to pyrimethamine, but highlyresistant strains may appear under laboratory conditions 127 The range of drug-resistance Au forms of the malaria parasite normally seasitve to drugs may in theory become resistant The problem of drug resistance must hence be considered in relation to the asexual tissue forms, to the aserual blood forms, and to the gametocytes, and evca, by a carry-over effect on the gametocytes, to the sporogonic forms in the mosquito Resistance to the Common Antimalarial Drugs Quinme The parasites of human malaria arc sensitive to quinipe at important but restricted phases in their life-cycie The schizogonic blood forms of all species infecting man are sensitive, and so are the gametocytes of Pyar, P osole, and P malariae A lessened sensitivity to quinine in the asexual blood forms of P fal ciparum, presumed to be natural, has been reported from several parts of the world An Italian strata of P falciparun has been shown to be rauch less sensitive to quinige than an indian strain observed under the same conditions, 14 and a Panamanian strain is reported to have shown a mild relative resistance, 14 the New Guinca Chesson strain of Pyrar seems to be less sensitive than the McCoy strain indigenous in the Vanced States of America 07 The "quinine resistant“ mataria reported from Mesopotamia after the first World War may possibly have some such explanation, but quinme-resistance was then held to explaio a poor claical response for which there were other possible causes Acquired resistance to quinide in human malaria is rare, if indeed at occurs at all Certain writers refer to a " dulling of the quinine elect", observed duning the first World War, but little support for this view has appeared since, and Fletcher, 14 with this wartime expenedcc in mind, found that quiorno resistance ia cases observed in Malaya vanuished when he gave the drug with his own hands fa avian malana, experimental attempts to induce resistance by intcasive quinine treatment bave either failed 193 199 or have achieved zo more than a slight resistance 16 A triling cross-resistance betheca pamaquine and quicide has been reported 19 Pamaquine Prolonged exposure to pamaquine may induce a slight resistance in the asexval erythrocytic forms of certain anan add mammalan species of ·58 CHEMOTHERAPY OF MALARIA Plasmodium,153 139 143 141 156 but acquired resistance in species infecting man has not been reported The asexual blood forms of P falciparum have a marked natural resistance to pamaquine Pentaquine, isopentaquine, and primaquine, 8 aminoquinolines related to pamaquioc, are presumed to have similar tendencies Pamaquine resistance in P gallinaceum confers no resistance to mepacrine, chloroquine, or proguanıl, but pamaquine-resistant strains may be slightly resistant also to pentaquine and quisine 139 Alepacrine Experimental attempts to induce resistance to mepacrine in avian and mammalian species have failed, 132 133 160 168 169 and the risk of acquired mepacrine-resistance in human malaria seems to be small There is an isolated report, however, of a relative resistance to mepacrine in strains of P falciparum observed in the Aitaipe-Wewak area of New Guinea These resisting strains regularly produced overt malaria in volunteers receiving 100 mg of mepacrine daily, a suppressive dosage which was efficient elsewhere in New Guinea and, indeed, in other parts of the world This resistance seems to have been acquired, for the resisting strains were isolated from a selected group of patients repeatedly given a standard quinne-mepacrine pamaquine treatment for recrudescent attacks Under the same conditions there was no evidence of resistance in P max 59 Chloroquine Like mepacrine, thus drug has little tendency to induce resistance in malaria parasites exposed to its action Experimental attempts to induce resistance in the avian parasites P gallinaceum and Plophurae, in the monkey parasite P cynomolgı, and in P vivar of man, have been unsuccessful 138 111 181 186 Amodiaquine Resistance to amodiaquine has not been reported and on chemical and pharmacological grounds any tendency in this direction seems improbable An attempt to induce resistance in Plophurae (chicks) was not successrui 18 Pyrimethamine Experience of pyrimethamine in the treatment and prevention of human malaria is still limited, and comparatively little is known of resistance to this drug in the species infecting man Resisting strains have been produced experimentally in P Cinomolgt,127 1635 P knowlesi,2235 and p Hvar 123 ·DRUG-RESISTANCE 39 A muld resistance in P falciparum has been reported from an area in Malaya where proguadil tesistance is well established,170 and Jones, cxperimenting on himself, has proved that a proguanıl-resistant falciparum strain from this area was resistant also to pynimetamine *** Experience in Kenya shows how quickly resistance in this species may appear and spread after mass treatments 150 Proguanil-Resistance As noted earlier, the tendency of proguanil to produce resistance has considerably modified early optimism and its place in the future patterns of therapy is now less certain the problem of proguanil resistance has been very extensively studied since it was first reported in 1947 In the laboratory a resistance to proguanil appears when parasites art cTposed to significant but sublethal doses of the drug, usually with repeated blood passage from host to host, conditions which are cxceptionally favourable for the emergence of resistant strains From later work, however, it seems that a resistance in P falciparum, P max, and P malariae may appear under the less favourable circumstances of field and hospital practice Range Resistance to proguanil may occur, theoretically, at any or all of the three stages in the life-history of the parasite on which it acts Experythrocytic forms The croerythrocytic forms of P sırax, and probably those of P malariae and P ovale, are naturally resistant to proguanıl, but the pre-erythrocy uc forms of P falciparum in the ussucs are highly sensitive It seems, however, that this sensitivity may be lessened in faleiparum strains with established resistance in the erythrocytic cyclc Primary falciparum infections have been acquired by newcomers to Malaya naturally exposed to resistant strains and alleged to have taken 100 mg of proguanil daily for weeks or months beforchand, morcover, a human Volunteer, bulten by mosquitos infected from a resistant Malayan sirain, developed overt falciparum malaria 11 days later despite regular daily doses of 100 mg of proguanil during the incubauon period 167 Resistance has also been reported in the pre-crythrocytic forms of the monkey parasite, P Gnomolgi, 117 and of the avian parasite, P gallinaceum 114 2. Asexual blood forms Acquired resistance to proguanil in the asexual blood forms has been reported not only in avan species of Plasmodium, but in three of the species inſecting man (table II) Prolonged contact with proguanil under appropriate experimental conditions may induce a resistance so high that the tolerance of the parasite for the drug may become ·60 CHEMOTHERAPY OF MALARIA greater than that of the host 142 Resistance has also been encountered in the course of clinical or preventive practice in malarious countries, though the recorded incidence is low, moreover, the resistance has been slow to develop and moderate in degree. 85 113 1400 1400 1446 TABLE I PROGUANIL-RESISTANCE IN THE ASEXUAL BLOOD FORMS OF VARIOUS SPECIES OF PLASMODIUM Specles B15 No How acqulred Months to acquire Degree Transmission through mosquitos P gallinaceum (chick) 132 168 Bxperimental 5 yes yos 168 7 P laphurae (duck) P cyhomolol (monkey) 14 148 180 147 high moderate moderate hlgh high high high moderato 16 yes yes Pfalciparum (man) 131, 162 98 140b 10 24 yes P Vivax (man) fleld conditions natural experimental field conditions 20 yes 163 141 171 48 high high moderate moderate P malarlae (man) 100 3 Gametocytes Resistance to proguanul, once established in the erythrocytic cycle, may extend to the gametocytes The experimental evidence on this point is scanty, but decisive Mosquitos have been infected with a proguanil resistant strain of P gallinaceum while the host chicks were receiving full doses of the drug, 183 and a resistant strain of P falcıparum from a gametocyte carrier receiving 100 mg of proguanil daily has -- la 100 Tt noccihle that 1,1 Rate of development Resistance to proguanil may appear quickly, or slowly, or 10deed not Under artifiming of treat. calculated to favour the survival of resisting organisms, a high tolerance to proguanul in the asexual blood forms of P falciparum and P vivax may appear within a few months ·DRUG-RESISTANCE 61 The usual conditions of clinical or preventive practice in malarious countries are never so favourable for the production of resistance as are those of the laboratory, they are seldom likely to be decisively unfavourable The possible trend of events in malarious regions where proguanil 15 used freely may be illustrated by experience in Malaya Here the drug was first used for treatment and prevention early in 1947, and records of the proguanil response in acute infections contracted in a single district have been kept for pearly six years At first, a single dose of 100 mg of proguanil would terminate acute falciparum attacks The first recorded failure of single dose therapy was in October 1948 and the first failure of a standard therapeutic course (300 mg x 7) in April 1949 By 1950, Acarly half of the falciparum infections treated failed to respond to a full therapeutic course In P vivax, a definite proguanul resistance was proved only in January 1951, and its incidence has remained low Resistance in P malaride has not yet been recognized 10 Malaya but has been reported from Jodonesia 100 Proguanil suppression in Malaya, started experimentally in December 1946, has since been used as a standard method of control on many rubber estates and by the Secunty Forces There was good evidence that a 100-mg dose twice a week was very efficient in the early days Five years later, in certain districts there were indications that a daily suppressive dose of 100 mg would sometimes fail, though by and large the drug was still thought to be a very useful suppressive Stability Once established, proguanil resistance in the asexual blood forms appears to be fairly stable It may persist through many asexual generations, and it may be upchanged by a transfer of the parasite to a fresh host whether by blood or mosquito-passage Resistance in P gallinaceum has been shown to last for at least a year without further exposure to the drug.. and to survive serial passage through mosquitos, 13 while there is suggestive evidence that resistance in P knowlesi may persist for at least eight months 12. Resistant strains of P cynomoigi, P falciparum, and P var have been shown to remain reststant after mosquito transmission to a fresh host 147 180 162 163 Spread under field conditions In latent infections, with ſew parasites in the peripheral blood, attempts to induce resistance have been unsuccessful 234 23 It may thus be assumed that the primary factors in causation are under-dosage and significant parasitaemia, operating together, and, under field condiuops, found par. ucularly in the under treated acute attack and in the under suppressed ·60 CHEMOTHERAPY OF MALARIA greater than that of the host II Resistance has also been encountered ia the course of clinical or preventive practice in malarious countries, though the recorded incidence is low, moreover the resistance has been slow to develop and moderate 10 degree 98 103 104 1408 1414 TABLE PROGUANIL RESISTANCE IN THE ASEXUAL BLOOD FORMS OF VARIOUS SPECIES OF PLASMODIUM Specles Bib Na How atqutred Months to acquire Degree Transmission through mosqu tos P gallinaceum (chick) 132 168 experimentat on high moderate moderate yes yes 166 7 Plophurae (duck) P cynomalol (monkey) 14 148 180 147 16 high high high high moderate yeg yos Pfalciparum (man) 10 21 yos 131 1621 98 140b 163 141 171 field conditions natural experimental P virax (man) yes field cond tions 4-6 48 high hloh moderate mode ate P mala lae (man) 100 3 Gametocytes Resistance to proguapıl, once established in the erythrocytic cycle, may extend to the gametocytes The experimental evidence on this point is scanty, but decisive Mosquitos have been infected with a proguanil resistant strain of P gallinaceum while the host chicks were receiving full doses of the drug, 133 and a resistant strain of P falcı parum from a gametocyte cercier recenog 100 mg of proguan) daily has la 100 T Doccible that 1 1 Rate of development Resistance to proguapıl may appear quickly, or slowly, or indeed not at all, depending on the conditions of exposure to the drug Under artifi cial conditions, with deliberate under dosage, with careful timing of treat ment, and with a serial transfer of parasites to fresh hosts calculated to favour the survival of resisting orgapusms, a high tolerance to proguanal in the asexual blood forms of P falciparum and P vivax may appear within a few months ·DRUG-RESISTANCE 61 The usual conditions of clinical or preventive practice in malanous countries are never so favourable for the production of resistance as are those of the laboratory, they are seldom likely to be decisively unfavourable The possible trend of events in malarious regions where proguanıl is used freely may be illustrated by experience in Malaya Here the drug was first used for treatment and prevention early in 1947, and records of the proguanil response in acute infections contracted in a single district have been kept for nearly six years At first, a single dose of 100 mg of Proguanil would terminate acute falciparum attacks The first recorded failure of single-dose therapy was in October 1948 and the first failure of A standard therapeutic course (300 mg x 7) in April 1949 By 1950, nearly half of the falciparum infections treated failed to respond to a full therapeutic course in P vivax, a definate proguanil resistance was proved only 10 January 1951, and its incidence has remained low Resistance in malariae has not yet been recognized in Malaya but has been reported from Indonesia 100 Proguanıl suppression in Malaya, started experimentally in December 1946, has since been used as a standard method of control on many rubber estates and by the Security Forces There was good evidence that a 100-mg dose twice a week was very efficient in the carly days Five years later, in certain districts there were indications that a daily suppressive dose of 100 mg would sometimes fail, though by and large the drug was still thought to be a very useful suppressive Stabıhty Once established, proguanil resistance in the asexual blood forms appears to be fauly stable It may persist through many asexual generauons, and it may be unchanged by a transfer of the parasite to a fresh host whether by blood or mosquito-passage Resistance in P galınaceum has been shown to last for at least a year without further exposure to the drug, ws and to survive senal passage through mosquitos, 133 while there is suggestive evidence that resistance in p knowlesi may persist for at least eight months 19« Resistant strains of P cynomolgi, P falciparum, and pyrar have been shown to remain resistant after mosquito transmission to a fresh host 107 190 191 169 Spread under field conditions In latent infections, with few parasites in the peripheral blood, attempts to inducc tesistance have been unsuccessful 154 150 it may thus be assumed that the primary factors in causation are under-dosage and significant parasitaemia, operating together, and, under field conditions, ſound par ticularly in the under treated acute attack and in the under suppressed ·62 CHEMOTHERAPY OF MALARIA smouldering infection The most fertile source of resistant parasites is likely to be the under-treated attack in which a parasite population of the order of 100-104 or more is exposed to a dose of drug sufficient only to destroy the more sensitive members Suppressive proguanıl-therapy is likely on theoretical grounds to pose a lesser problem of resistance, for parasitaemja in the under suppressed infection will usually be low But here again under-dosage from irregular administration will greatly raise the odds With missed doses, parasitaemia may rise to a clinical level and the dual effect of a high concentration of parasites and a low concentration of drug come into play Resistance developing from under-dosage is at first a personal problem, restricted to the subjects whose parasites have become proguanil tolerant In time the resisting parasites would die out were they not transferred to a new host Resistance becomes a community problem when the resisting strains are diffused by mosqui The extent of spread is determined by parasites in mosquitos, the transmission of resistog strains, no less than their 10jtration, is likely to be related to under dosage Recognition Proguanil resistance may declare itself in various ways (a) The failure of a single dose to achieve in mild acute infections a remission of symptoms and to eliminate the schizogonic cycle in the blood is evidence of a slight loss of sensitivity This was the earliest indication of a developing resistance in Malayan strains of P falciparum Today, however, routine single dose proguanil therapy is not recommended and thus method of detecting early resistance has no more than experimental interest The failure of a standard therapeutic course of 300 mg daily in acute infections to clear asexual parasites from the blood within seven days indicates a growing resistance in the schizogonic blood forms, but again this method of assessing resistance will usually be experimental, for proguanil alone is seldom recommended today for the treatment of the acute attack (6) The occurrence of overt malaria in inhabitants of endemic areas who are known to have taken regular suppressive doses of proguanil may suggest that resistance is developing, although perhaps only in the asexual blood forms of the parasite (c) The occurrence of overt malaria in newcomers who have taken 100 mg proguanil daily without fail since arrival in the malarious area suggests the transmission of parasite strains which are resistant to proguanil ·DRUG-RESISTANCE 63 at various stages of their life-cycle The first suspicion of resistance in the prc erythrocytic forms of certain Malayan strains of P falciparum arose in this way The difficulty is that one can seldom be certain that the proguanil has been taken with unfailing regularity Resistance at the sporogonic stage cannot be assessed by simple clinical means The conditions of transmission in most malanous countries are too complex, and the only valid evidence is likely to be that which comes from mosquitos inſected experimentally in the laboratory Prevention Proguanil resistant parasites are not likely to anise in the individual subject of the schizogonic cycle in the blood is permanently interrupted by clicient treatment or inhibited by efficient suppression They cannot be transmitted and spread in the community of the continued development of the gametocytes is inhibited by adequate therapy, clinical or suppressive, for every infected person In most malarious countries this is possibly a counsel of perfection The occasional resisting strain is likely to emerge in any community using proguanil on a large scale and lacking a high level of medical organization whether the resisting strains are few or many, whether they die out or spread, must finally be determined by the prevailing standards of treatmcot, suppression, and mosquito control Treatment must be good enough to eliminate ascxual parasites from the blood, and continued long enough to sterilize gametocytes Suppression must be regular enough to prevent the transicnt bursts of parasitaemia shuch may come with missed doses The fact that resistance to proguanil is most likely to arise when a large parasite population is exposed to, but not eliminated by, the drug 15 in itself a suficient reason why acute infections should not be treated with proguanil alone When the drug is used for malaria suppression, resistance is likely to arise only when the plasma concentration falls low enough to permut an active proliferation of parasites Irregular dosage is likely to be the common cause, and the key to prevention probably lies in a good suppressive discipline For a time the loss of effect from early resistance can be met by an increase in dasage--this is apparently the situation in parts of West Africa-but a further rise or spread of resistance would necessitate an immediate change of drug It is not always casy to arrive at a decision when resistance is mild or sporadic, and when proguanıl, though still a useful suppressive, sometimes falls What margin of failure is to be considered tolerable in the licht of the other virtues of the drug ? To what extent should we weigh in the balance the great potential value of proguanil as a salc causal prophylactic in falciparum infection and as a non louc stenlizing agent for mosquito ·64 CHEMOTHERAPY OF MALARIA infections ? This is a problem which faces public health authorities in some territories today, and there is no clear answer We may take the view that the most efficient suppressive drug should always be the drug of choice the 4-aminoquinolines and mepacrine are better suppressives than proguanil under the conditions prevailing, for example, un certain parts of Malaya Or we may regard the direct action of proguapıl on the preerythrocytic and sporogonic forms as a powerful asset not to be discarded ightly A deciding factor might well be the proguanil sensitivity of the prevailing strains at the pre-erythrocytic and sporogonic phases of growth Should this sensitivity be lost, there would be a strong indication for a change-over to another drug Cross-Resistance The fear that a resistance to one drug might confer on malaria parasites a general tolerance to other antiossalarial drugs has proved to be all founded Cross-resistance certainly occurs, sometimes to a marked degree, but the phenomenon presents no clinical problem which cannot be met simply by a change of drug Experimental evidence suggests that the only important compounds to which malaria parasites may show a significant crossresistance are proguanıl, pyrimethamide, and the sulfonamides (table III) Cross-resistance between proguanil and the sulfonamides has much theoretical interest, but the sulfonamides are not used as malaria remedies, and there is little danger of proguanil-resistant malaria from sulfonamide therapy in other diseases The extent and significance in human malaria of a cross resistance between proguapıl and pyrımethamine has still to be assessed Pro- I. resistance in the local falciparum strains Resistance to pyrımethamine 10 the Chesson strain of P wrar confers a partial resistance to proguanil 123 This disturbing cross-resistance might well restrict the use of proguanil and pyrımethamine in territories where resistance to one of them is known to occur The three drugs, proguanil, pyrimethamine, and sulfadiazine, all seem to act on malaria parasites in much the same way-by inhibiting nuclear division They all tend to induce a high resistance in parasites exposed to their action, and resistance in any one of them may extend to one or more of the others Quinine, mepacrine, and the 4-Aminoquinolines do not induce significant resistance nor are they involved in cross-resistance They are chemically unrelated to proguanil, pyrimethamine, and the sulfon- ·DRUG-RESISTANCE 65 TABLE 11: CROSS RESISTANCE BETWEEN ANTIHALARIAL DRUGS Speclet Bib No Primary acquired tes stance Assoclated roulstance Resistant atraln at 11 sansitive to P gallinaceum 134 138 137 sulfadiazine proguan! other sulfonamider quinine mepaçino pamaquina quinine me pacrino sulfadiazine 168 proguanit 136 157 proguan!! pamaquine sulfadlazine (slow) pentaquine quinine (slight) 139 proguanit mepacrino sulladlazine chloroquine P berghel 45 sulladlarına proguanil (slight) pyrimethamina (sllpho 48 proguanid Plophurze 168 propvanil pamaquino quinina me pacrine chloroqu ne amodiaquno chloroquine mepacrina pentaquine suitad ezino Pcynomolg! 147 160 propuanli 127 choroquine P knowled Pfalciparum Privax 165 125 149 pyrimethamino proguanil proquant proguanto pyrimethamine propuanll pyrimethamino pyrlmethamine 141 chloroquina chloroquina 122 proguanil amides, and they probably act on malaria parasites by a different metabolic route Schmidt and his colleagues have drawn attention to a possible parallel with the bacteriostatic sulfonamides and the bacteriocidal peni cillins, and suggest that resistance in malaria parasites develops in relation to drugs which inhibit the growth of the parasites, rather than to drugs hich destroy them 140 Origio and Mechanism of Drop-Resistance Drug resistance in human malaria may be explained in vanous ways We may assume that the new chemical environment imposed by the drug induces a change in all the parasites enabling them to find a metabolic pathway of escape from its lethal effects, this is the theory of physiological adaptation Or we may assume that resistant parasites anse by chance as ·66 CHEMOTHERAPY OF MALARIA rare mutants and that the drug 15 merely a selective agent, this is the theory of spontaneous mutation Or, again, we may accept mutation as the key to resistance, but assume that mutations are bound up in some way with exposure to the drug, this may be called the theory of induced mutation Yet again, we may accept the simple theory advanced by Yudkin,173 which assumes that cell division does not necessarily distribute the systems responsible for resistance equally between the daughter cells Repeated divisions would produce a clone of cells with the average resistance of the parent cell, but with a distribution of greater or lesser resistance around that of the parent cell The drug might then have the effect of destroying the cells of lesser resistance, with a progressive shift of the average to wards a higher resistance, this is the theory of clonal variation with selection Physiological changes directly induced by environment involve poten. trally all members of an exposed population They are thought to be non inheritable and hence impermanent Changes arising from mutation, on the other hand, involve the genetic or heredity producing mechanism of the cell and are passed on from generation generation They appear only in a minute proportion of cells, and tend to be stable and permanent, finding expression in the population as a whole by the selective influence of environment and they are liable to occur as a sudden event, or dis continuous " step wise series of events, rather than as a gradual and continuing process Clonal variation would similarly be expected to produce inheritable change, tending to permanence, but occurring rather as a smooth and continuing process The mechanism of drug resistance The observed phenomena of drug resistance in malaria, while suggesting a genetic origin, give little clue to the mechanism of change The character of resistance is carried throughout the life-cycle of the parasite in vertebrate and invertebrate hosts, it continues unchanged from generation to generation in the asexual blood forms, it tends to persist when the exciting stimulus has been withdrawn, and it is readily produced only in parasite populations large enough to include a few resistant members An abrupt appearance of resistance has been reported but a rather gradual development seems to be more usual These are phenomena for which spontaneous mutation, induced mutation, or clonal variation, could equally provide satisfying explanations, though it is perhaps significant that the drugs which give rise to serious resistance are those which apparently interfere with the division of nuclear chromatia Beyond this general statement we cannot go, for genetic studies of malarla parasites are exceedingly difficult, and Iittle work seems to have been done on this subject ·DRUG-RESISTANCE 67 The nature of resistance If there is little assurance as to the ongin of resistance in malaria para. sites, there is even less regarding the changes within the parasites which enable them to resist The problem is bound up with the metabolism of the parasites and with the precise mode of action of drugs, and custing knowledge on these subjects is still fragmentary Drug resisting parasites are clearly different in some way from those which do not resist The differences are not evident in their form, nor, in the absence of the drug, in their behaviour They are subtier differences related to the metabolism of the parasite cell We may conocive, for crample, that the permeability of the parasite to certain drugs is subject to variation Resistance might then arise by the selection of variant parasites which deny access to the icterior of the cell The resistance of trypanosomes to organic arsericals has been explained in this way Or variation might involve the enzymic constitution of the parasite cell, with resistance appearing where, for example, a variant parasite is able to dispense with an enzyme system normally subject to interference by the drug If, as we may suppose, a drug acts by disturbing the synthesis or utilization of some essential metabolite, the parasites may conceivably evade thus action (a) by an increased production of the metabolite, or (b) by finding an alternative pathway for its synthesis, or (c) by a capacuy to grow in its absence The sulfonamides appear to act on certain bacteria by competing with the metabolite p-aminobenzoic acid in an essential enzymic system, while an increased production of this metabolite is associated with sulfonamide resistance Can we relate this evidence to sulfonamide-resistance in malana ? Pteroylglutamic acid, a product of the metabolism of p-aminobenzoic acid, inhibits the action of sulfadiazine aod proguanil in certain forms of malaria 15 May we then presume that resistance to thesc drugs is related to parasite variations involving the synthesis of, or necd for, pteroylglu. tamic acid ? Evidence in this highly complet field is steadily accumulating, but whether, or to what ettent, these or similar mechanisms come into play in drug resistant malaria is not yet clear Commentary The main phenomena of drug resistance in malara may be stated in a few words At particular phases in their life-cycle, malaria parasites cvolve a means of surviving in the presence of drugs a buch pormally destroy them The resistance seems to be causally related to the exposure, usually prolonged and intermittent, of large parasite populations to a near letha dose of drug The resistance is inheritable and fairly stable It involves ·68 CHEMOTHERAPY OF MALARIA mainly the schizogonic forms in the blood, but in some species it occurs also in the pre erythrocytic forms, and in the gametocytes The drugs which excite resistance are those which appear to act by inhibiting nuclear divisionproguanıl, pyrimethamine, and the sulfonamides Cross resistance between these drugs may occur Drugs like quinne, mepacrine, chloroquine, and pamaquine-which appear to act in some other way do not give rise to significant resistance The most satisfying theories assume that resistance is due to the selective survival of resisting organisms arising by mutation or by “clonal variation" Whether the resisting organisms appear at random or are changed in some way by the drug we do not know Nor do we know in what way the parasites are changed Do they resist the penetration of the drug, or does resistance depend on their enzymic constitution ? Have the resistant parasites some other pathway for the synthesis of a necessary metabolite, a synthesis normally arrested by the drug ? If so, is the same enzyme system involved at the three phases of the life-cycle in the tissues, the blood, and the mosquito's stomach ? Having arisen at some point, does resistance extend throughout the cycle ? Is resistance a permanent quality or will it die away in time when the exciting stimulus is withdrawn? These questions, and the doubts which they engender, emphasize the need for a better understanding of the intricate problems still awaiting solution ·CHAPTER 5 THIE CLINICAL USE OF ANTIMIALARLAL DRUGS Chemotherapy has scored some of its greatest successes in the treatment of human malaria There are few infections more responsive to well. directed therapy, and ſewer in which therapy can be applied with results so satisfying on so wide a front The first, perhaps still the greatest, success came with the discovery three centuries ago that the bark of cinchona would "cure" certain fevers The patient sick with the ague took the remedy, and was soon well again-the simplest and still the main clinical approach to malaria chemotherapy But the fever often came back, and as early as the 17th century Sydenham had broadened this simple concept to embrace the idea of prevention He gave the bark to persons who expected a recurrence of the fever but who were not sick at the time After the isolation of the principal alkaloids of cinchona, the small daily dose of quinine came to be adopted as a clinical preventive The practice of using cinchona or quinine to end the malarial attack and to prevent further clinical manifestations of the disease continued unchanged until the end of the first World War The introduction of cxperimental malaria therapy soon after its termination led to a clearer under. standing of the natural history of malaria in man, while, as has been described, the synthesis of pamaquine in 1926 started a trickle, soon to become a stream, of new compounds lethal to the parasite New methods alike in its curauve and preventive aspects, reflects the advances achieved by laboratory research Twenty five years ago the prospects for radical prevention in falciparum infection here remote and prolonged courses of quinine were advocated for radical cure Today, well timed therapy with minute doses of proguanil szll cradicate P falciparum at a pre-clinical stage in the human host, while a few days' therapy with ooc of the 4-amino quipolines will usually cure the established infection Talciparum malana may now be suppressed with anerscandefliciency, with a safety and economy, • Seo Seleste bibliotrophy lo t14182 (pure 119 69 - ·70 CHEMOTHERAPY OF MALARIA which must surely approach the ultimate limits of advance in this direction But with vivax infection progress is less impressive We lack a safe and sure preventive, though pyrimethamine may take us a step forward, and radıcal cure still depends on a prolonged treatment with drugs of moderate toxicity The Aims of Malaria Chemotherapy 1 The life cycle of the parasite and the widening range of therapy From the account given to chapter 2 of the relation of its various phases to the mode of action of antimalarial drugs, it is clear that the malaria parasite lies open to attack by well directed therapy throughout most of its complex life-cycle The sporozoite alone seems to be resistant The schizogonic forms in the fixed tissues and circulating blood, the gametocytes and, through a carry-over effect, the sporogonic forms in the mosquito, are alıke vulnerable to appropriate therapy, with differing effects on the course of infection (table IV) 4 TABLE IV CLINICAL RANGE OF MODERN THERAPY IN HUMAN MALARIA Stage In Ife cycle of parasite Clinical range of present day drugs Schizoqonic forms in fixed tssues Schizogonic forms in the blood causal prophylaxis of falciparum Infection before the parasites reach the blood radical cure of vivax Infection termination of the acute attack radical cure of falciparum Infection suppression of all forms of malarlal Infection suppressive cure of falciparum Infection on In source of gametocytes with Indirect effect on transmission direct effect on transmission Gametocytes 2 Therapeutic resources The aims of malaria chemotherapy may now be more closely defined Broadly, they remain what they have always been--to cure the patient sick with malaria and to prevent malaria or its clinical manifestations under all the varied circumstances in which they may appear We think first of the individual If he is exposed to infective mosquitos we aim to protect him by sterilizing infection while it is still symptomless, if he becomes ·CLNICAL USE OF DRUGS 71 sick with maları, to relieve his symptoms as speedily, as safely, and as comfortably as possible, with permanent cure of his infection If he is a symptomless carrier, we aim to eradicate the inſection, or, fulog this, to suppress it at a continued subclirucal level for the community we aim to break the chain of transmission by directing treatment, curative and suppressive, toward the destruction of gametocytes or to the inhibition of their production or development The ideal drug would meet all these demands without harm to the patient It would be quick in action and unvarying in its effects It would be active in all forms of human malana, at all stages, and it would not induce resistance in the parasites Furthermore, it would be easy to administer by the oral or by the parenteral route, and it would be stable and cheap No known drug sausfies all these exacting requirements, though most of them can be met by a judicious selection of the drugs now Available The compounds which fill a useful role in malarial therapy are all mem bers of four chemical groups--the 4-aminoquinolines and allied compounds, the 8 aminoquinolines, the biguanides, and the pyrimidines Table V Lists the compounds on which present-day therapy is mainly based TABLE V DRUGS ON WHICH PRESENT DAY MALARIA CHEMOTHERAPY IS BASED Chemical coup Main members of the group Activity 4-aminoquinot net and related compounds chloroquina amod aquine mepacrine Quin ne -aminoquinoliner primaquina Pamaquint Essentially schizontocidet Litte action on excerythrocytic parat tes or on the game tocytes of P falicarum The most useful druge known for treating scute malaria at except quline are powerful tuppre- Blvet low to city Do not hiduce drug ros stance Poor schlrontocide but active against cametocytes and against troerythrocyte parasiten Mal unei gametocytocidat treatment and mad cal curo in vantec ton Moderately toxic Do not Induce significant druge stance Schizontocide and sporonfacld. Active Ito nga not the 10erythrocyt c forme of Pfalc parum Man viet cual prophy- Larit in tatc parum infection soppreion and linh tion of sporogony Nontorke Liable to induce drvo-fts stance Activity tlmblar to that of proguan but has some action so on the trourythrotyc forms of Par Hain uva ostor pro- Quand tow boucity Llable to Induce Arvo-osalanc Sloveniden proguan Primemes Pyrimidler pylmethamine ·70 CHEMOTHERAPY OF MALARIA which must surely approach the ultimate limits of advance in this direction But with vivax infection progress is less impressive We lack a safe and sure preventive, though pynimetamine may take us a step forward, and radical cure still depends on a prolonged treatment with drugs of moderate toxicity The Aims of Malaria Chemotherapy 1 The life-cycle of the parasite and the widening range of therapy From the account given in chapter 2 of the relation of its various phases to the mode of action of antimalarial drugs, it is clear that the malaria parasite lies open to attack by well directed therapy throughout most of its complex life-cycle The sporozoite alone seems to be resistant The schizogonic forms in the fixed tissues and circulating blood, the gametocytes and, through a carry over effect, the sporogonic forms in the mosquito, are alike vulnerable to appropriate therapy, with differing effects on the course of infection (table IV) TABLE IV CLINICAL RANGE OF MODERN THERAPY IN HUMAN MALARIA Stage In life cycle of parasite Ctnical range of present-day drugs Schizogonic forms in fixed tissues Schizogonic forms in the blood causal prophylaxis of falciparum Infection before the parasites reach the blood radical ture of vivax Infection termination of the acute attack radical cure of falciparum infection suppression of all forms of malarial Intection suppressive cure of falciparum Infection reduct on In source of gametocytes rith Indirect effe on transmission drect effect on transmission Gametocytes 2 Therapeutic resources The aims of malaria chemotherapy may now be more closely defined Broadly, they remain what they have always been--to cure the patient sick with malaria and to prevent malaria or its clinical manifestations under all the varied circumstances in which they may appear We think first of the individual If he is exposed to infective mosquitos we aim to protect hum by sterilizing infection while it is still symptomless, if he becomes ·CHNICAL USE OF DRLAS 71 sick with malaria, to selieve his symptoms as speedily, as safely, aod as comfortably as possible, with permanent cure of his sofection if he is a symptomless carrier, we aim to eradicate the infection, or, failing thus, to suppress it at a continued subclinical lesel For the community we aim to break the chain of transmission by directing trcalment, curative and suppressive, toward the destruction of gametocytes or to the inhibition of their production or development The idcal drug would meet all these demands without harm to the patient It would be quick in action and unvaryiog 10 its effects it would be active in all forms of human malaria, at all stages, and it would not induce resistance in the parasites furthermore, it would be casy to administer by the oral or by the parenteral route, and it would be stable and cheap No known drug sausfies all these e tacting requirements, though most of them can be met by a judicious selection of the drugs now available The compounds which fill a useful role in malarial therapy are all members of four chemical groups--1hc 4-aminoquinolines and allied compounds, the 8 aminoquinolines, the biguanides, and the pyrimidines Table V lists the compounds on which present-day therapy is mainly based TABLE V DRUGS ON WHICH PRESENT DAY MALARIA CHEMOTHERAPY S BASED Chemical group Man members of the group Activity aminoquin plin and roland compounds chloroquine atrod agung Medec u nina saminoquinolines primaquina thieu trent sity schlzontorlden te achon on erberythrocytic para o Do Iho omy tocytes of Pron parum The most useful Up tnown for voating acuto maar A oncept Quin ne are powerful subpro 1 Low to city Do not induce drug res stance Poor schizotocidas but active against Dathetocytes and aguingt erventh ac yire Daruntei Men wie ametocytoc dal treatment and red col cu tax bute tion Moderately tou Do not induce significant drug tot stanco Schitontocide and Dorontocido Acur 1199 ags nat the loerythrocytic forms of fak parum Menus cavul proohylas in tal catum Intest or Suposeguen ang tnt bihon of sporogony Non-tox Lable to induce drugo stanco Acuity are that of around but some ortion is on the terythrocytys torte o1 P Thar Van Viet Tor ouent to bakity Llable to indust drugih stanco Biowanides Droguent Pyrimidines Dylmethamine ·72 CHEMOTHERAPY OF MALARIA The Confusions of Dosage A severe case of falciparum malaria may require 10,000 mg (150 grains) of quinine before the fever is controlled, an evanescent febrile episode in an old standing infection may be terminated by three or four tablets of aspưin A proguanil sensitive falciparum infection may be clinically cured by a single proguanil tablet of 100 mg, a resistant infection may still persist when the patient has received 50 times this amount These extreme examples illustrate the fallacies which may underlie attempts to fix arbitrary levels of dosage, suitable for all malaria infections, at all times, and in all places Confusion arises mainly from the immunity factor in the thera peutic response, from differences in the geographical strains of the para sites, and from drug resistance 1 The immunity factor The response to treatment in malaria is usually, perhaps always, an expression of a dual effect The plasmodicidal effect of the drug is rein forced by a contribution from the tissue defences In the early stages of a primary infection in subjects with little immunity the contribution from the tissues may be small, 10 old standing infections the tissue defences may suffice of themselves to break the schizogonic cycle of the parasite Logi cally, the dose of a drug should then be related to the immune status of the subject Immunity, however, is not always easy to assess, and the dosage usually recommended is that appropriate for infection in the non immune subject Medical officers, with their special knowledge of the malaria with which they have to deal, are best able to decide whether, and to what extent, they may safely reduce the dosage ordinarily recommended for treatment and suppression 2 Strain of parasite As noted elsewhere, geographical strains of malaria parasites sometimes differ in their sensitivity to a particular drug Primaquine is more active against Korean vivax strains than against the New Guinea Chesson strain, the Costa strain of P falciparum seems to be less sensitive to quonne and mepacrine than the McLendon strain of the same species, a Dutch strain of P var has been showa to be less sensitive to Salvarsan than the Madagascar strain, which is probably of African or Asian origin and other examples have been recorded The differences are seldom marked, and they do not appear to be common, but at least they show that a drug dosage may not necessarily have universal validity, and they may some times explain why a drug regimen which gives good results in one part of the world may be disappointing in another ·CLINICAL USE OF DRUGS 73 Drug resistance Dosage is normally based on the response to treatmeet of fully sensitive Parasites should the parasites become resistant, the recommended dosage might be seriously at fault Fallacy from this source, however, is unlikely o anse with quinine, mepacrine, chloroquine, or amodiaquine, the drugs on wluch the treatment of acute infection is based The only drugs givog ise to serious resistance are proguanil and pyrimethamine Age and body-weight about 110 lb (50 kg) in weight, and individuals may weigh less than 100 16 (45 kg) The calculation of dosage on a body weight basis, taking 150 lb as the norm, is probably a sound rule For children up to the age of 12 years, a modified Young's formula * gives a good approximation to the body weight dosage Children tolerate antimalanal drugs quite well, and should there be uncertainty as to the dosage for serious infection, it s wiser to give too much rather than too little 5 Base or salt Another source of confusion is the practice of expressing dosage sometimes as the salt, sometimes 10 terms of the content of active base A proprietary brand of chloroquine is marketed as tablets of 250 mg with no mention of the amount of active base, another brand, sold as tablets of 200 mg, has the base content printed in smaller type on the label, both contain 150 mg of chloroquiae base Ao amodisquine tablet of 261 mg, on the other hand, contains 200 mg of active base, aod no other figure appears on the label The dosage of pamaquine is even more confused an 18 mg tablet of the naphthoate and a 10 mg tablet of the dihydrochloride alıke contain 8 mg of active base, but the figures wuch receive prominence are 18 mg and 10 mg for the older drugs, like quinine, wc shall continue to think or dosage in terms of the salt, but for the newer drugs there is no good reason for the persistence of this confusing anomaly The logical course is to give all dosage in terms of the active base, no other figure should appear on manufacturers' labels Where this is not possible, the dosage in terms of sale having been established by custom, the base content should at least be stated The base content of the antimalarial sales in common use is given in Annex 2 • Doure for children - dwi dosar x Bte net birthday ·74 CHEMOTHERAPY OF MALARIA 6 Comment The drug dosage recommended throughout this account assumes that the patient is an adult weighing about 150 16 (30 kg), that he has no sigar ficant immunity to malaria, and that the parasites have no natural or acquired resistance Under particular circumstances this dosage may be inappropriate The physician alone, from his special knowledge of these curcumstances, can evaluate the modification which may be necessary The Malaria Patient * 1. The simple acute infection The primary clinical aim in acute malaria is to bring the attack to an end, quickly, safely, and with minimal discomfort to the patient The symptoms are due to the rapid proliferation of asexual parasites in the blood, they must be destroyed The most useful drugs for this purpose are the 4-aminoquinolines and related compounds (tables Vi and VII) When these drugs are given at the recommended dosage, they may be TABLE VI ADULT DOSAGE OF 4-AMINOQUINOLINES AND RELATED COMPOUNDS FOR THE SIMPLE ACUTE ATTACK Dosage (mg) and days Drup Total 1 2 3 5 6 7 600 + 300 C 300 300 1 500 mg Chloroquine base or Amadlaquino base or Mepacrine or Quininec 600 400 400 1 400 mg 200 X 55 2 000 (30 300 300 300 300 300 300 2 000 2 000 2 000 2 000 2 000 2 000 (30 (30 (30 (30 (30 (30 Orsins) gralns) Orains) grains) grains) grains) 2 800 mp 14 000 mg (210 gra na) grains) 1 Second dase 6 hours after flret Every 6 hours « Qulnine in dlvlded doses Some authorities reduce the daily dose to 20 grains after the first 2 days (total 160 gralny) Note The dosage of antimalarlal drugs recommended by workers in different countries shows considerable variation For example in India It has been stated that a sing e dase of 600 mg of chloroguine or amodlaquine or 3-day course of 20 to 30 gralns ot quinine dally wil effect clinical cure in the majority of mild Infect ons • In general thus account is restricted to the specific treatment of malaria Nurs ng management relief of special symptoms and convalescence are in accord with tcpcral prio ciples ·CUNCAL USE OF DRUGS 75 TAOLL VI1, PROPRIETARY PREPARATIONS AND SALTS OF DRUGS RECOMMENDED FOR THE SIMPLE ACUTE ATTACK Drug san Common prophetary met Vous preparations Chloroquina diphosphata Retochin Aralen Avtoclor Nivaquina montattato Tablete of 250 mg containing 150 mg ot chloroquine ban.donado in terme of ten Tablets of 204 mp containing 150 mg ot dete or of 136 mg of vast com talning 100 mg of bass or ol 608 7D ot mi cong noire X 9 Đa, dosego in terms of base Tablet containing 200 mg of date. dosage in time of a Tablets of 100 mo containing 19 of bun, dota in terms of aimydrochloride dihydrate Acid sofution, douage in terms of salt Amodioquine othydrochloride dlhydrate Camoqula Mapaceing dihydrothlorido dihydrate Atebrin Alsbring Quinocrino Quinine dlhydrochloride or uitate expected to bring about a remission of symptoms within from one to three days and to eradicate most falciparum and ovale infections Infections due to P virax or p malariae are likely to secur The treatment of relapsing infections is discussed in a later section (page 81) The drugs are normally given by mouth but, should the paucot be unable to retain the drugs because of nausea or vomiting, the whole or some part of the dose must be given by injection in this eseni, oral treatment must be resumed as soon as possible Parenteral treatment is discussed in the sectson on grave infection (page 77) o The " loading dose" has been the general synthetic compounds, ont Quininc altains a high scrum concentralion fairly quickly, morcoscr, heavy dosage would be unsound on clinical grounds, for these reasons quinine 15 gyen at a steady level throughout treatment Microcrine and the 4 ampoqmnoides, on the other Sipd, reach their pel concentration in the serum more slowly, a delay which is effectively olettome by“ loading the dosage at the beginning of the course There can be lit doubt that therapy with the synthetic drug is more rapidly effective today than it was with merzprice before the second World War, and that the " loading dose" is largely responsible for the change ·76 CHEMOTHERAPY OF MALARIA (6) Chloroquine Thus drug is probably unsurpassed by any known remedy for the treatment of the acute malaria attack It has the same plasmodicidal range as mepacrine, but is more active and, unlike meparine, does not stard the skın At normal dosage, its toxicity is very low No contraindications to its use have been reported The drug is issued under various proprietary names as tablets containing 100 mg, 150 mg, or 300 mg of chloroquine base (c) Amodiaquine This drug closely resembles chloroquine in its antimalarial activity The differences are probably too small to be clinically significant The toxicity at therapeutic dosage is very low, 10 contraindications have been reported (d) Mepacrine The value of mepacrine in the treatment of acute malana was attested by extensive experience of the drug gained both before and during the second World War It is reliable and rapidly effective, but not entirely free from disconcerting side effects Temporary abdominal discomfort in the first few days of therapy, and a harmless yellow staining of the skin and eyes later on, are fairly common, rarely, the drug may induce mental symptoms varying from a mild depression or excitement to a wild mania, epileptiform convulsions have been reported with parenteral administra- The mental effects ("mepachine psychoses ') tend to clear up fairly +an (e) Quinine There is a prevailing tendency today to decry quinine True, quinide has defects from which the newer synthetic remedies are free it causes un. pleasant cinchonism, it may occasionally precipitate blackwater fever, and It is less likely to eradicate infection But, when all is said, for the immediate treatment of the acute infection, quinige remains a remarkably safe and effective drug For the treatment of the acute malaria attack, quinide is given in solution in capsules or as tablets of the dihydrochloride or sulfate in divided doses three or four times a day Sugar-coated tablets are less unpleasant to the taste, they are usually efficient but they carry the off chance of defective absorption Children tolerate quisine very well and ·CLNICAL USE OF DRUGS scem to seed relatively higher doses than adults Serious toxc effects from therapeutic doses of quaine are extremely rare Personal idiosyncrasy, and a history or threat of blackwater ſever, are the main contraindications to its use The termination of pregnancy duriog quinine treatment is far more likely to be due to the malaria than to quinine, but most doctors would probably wish to play for safety by using some other drug 2 The grave infection The clinically grave or parasitologically intense malana infection is a medical emergency demanding immediate treatment and meticulous care until the danger is past The cause is nearly always P falciparum, rarely P war Waroing symptoms may appear with alarming suddenness in the course of a simple falciparum attack and a few hours delay may mean the diTerence between life and death The clinical and parasitological indications for regarding an infection as serious, or potentially serious, are coma or mental clouding, collapse, jaundice, severe vomiting or diarrhoea, high parasitaemia, and the presence of falciparum schizonts or very young gametocytes in blood films Every falciparum infection with more than 10% of the red cells infected is serious, however mild the symptoms In these infections the microscope sometimes gives a more reliable indicanon of gravity than a clinical examination When the patient with grave infection is conscious, co-operauve, and able to swallow, he may be given oral treatment with the same drugs, and at the same dosage, as for the simple attack (page 74), but even in these cases many physicians prefer to give the first one or two doses by injection for greater assurance of prompt absorption Coma, lomiting, and severe nausea are clear indications for administering by intramuscular or intravenous injection Oral therapy should be substituted for parenteral therapy as soon as the danger 13 passed, and the patient is able to swallow the drugs and retain them The most effective drugs in these cases are quinine, chloroquoe, amodia quine, and mepcriae (table VIII) Conservative physicians of an older school would probably give this order of precedence, their younger colleagues would be more likely to give pride of place to chloroquine There would probably be general agreement, however, that chloroqune is a better drug than quoinc for otramuscular administration (a) Quinire With the exception of merachide, all the drugs recommended for the treatment of grave Palaparum infection may be given either by intramuscular or by intravenous Injection We must remember, forever, that ·76 CHEMOTHERAPY OF MALARIA (6) Chloroquine This drug is probably unsurpassed by any known remedy for the treat ment of the acute malaria attack It has the same plasmodicidal range as mepacnine, but is more active and, unlike mepacrine, does not stain the skin At normal dosage, its toxicity is very low No contraindications to its use have been reported The drug is issued under various proprietary names as tablets containing 100 mg, 150 mg, or 300 mg of chloroquine base (c) Amodiaquine This drug closely resembles chloroquine in its antimalarial activity The differences are probably too small to be clinically significant The toxicity at therapeutic dosage is very low, no contraindications have been reported (d) Mepacrine The value of mepacrine in the treatment of acute malaria was attested by extensive experience of the drug gained both before and during the second World War It is reliable and rapidly effective, but not entirely free from disconcerting side effects Temporary abdominal discomfort in the first few days of therapy, and a harmless yellow staining of the skin and eyes later on, are fairly common, rarely, the drug may induce mental symptoms varying from a mild depression or excitement to a wild mania , epileptiform convulsions have been reported with parenteral administration The mental effects ('mepacrine psychoses ") tend to clear up fairly quickly when the drug 15 withdrawn, and the convulsions, while alarming, disappear without harmful sequelae Syphilts of the central nervous system and a history of nervous system sequelae from previous mepacrine therapy, are contraindications to the use of the drug (e) Quinine There is a prevailing tendency today to decry quinine True, quinide has defects from which the newer synthetic remedies are free it causes uapleasant cinchonism, it may occasionally precipitate blackwater fever, and it is less likely to eradicate infection But, when all is said, for the immediate treatment of the acute infection, quinine remains a remarkably safe and effective drug For the treatment of the acute malaria attack, quinine is given in solution, in capsules or as tablets of the dihydrochloride or sulfate in divided doses three or four times a day Sugar-coated tablets are less unpleasant to the taste, they are usually efficient but they carry the off chance of defective absorption Children tolerate quinine very well and ·CLINICAL USE OF DRUGS 77 seem to need relatively higher doses than adults Serious toxic effects from therapeutic doses of quinine are extremely rare Personal idiosyncrasy, and a history or threat of blackwater fever, are the main contraindications to its use The termination of pregnancy during quinine treatment is far more likely to be due to the malaria than to quinine, but most doctors would probably wish to play for safety by using some other drug 2 The grave infection The clinically grave or parasitologically intense malaria infection is a medical emergency demanding immediate treatment and meticulous care until the danger is past The cause is nearly always P falciparum, rarely Pwvax Warning symptoms may appear with alarming suddenness in the course of a simple falciparum attack and a few hours delay may mean the difference between life and death The clinical and parasitological indications for regarding an infection as serious, or potentially serious, are coma or mental clouding, collapse jaundice, severe vomiting or diarrhoea, high parasitaemia, and the presence of falciparum schizonts or very young gametocytes in blood films Every falciparum infection with more than 10% of the red cells infected is serious, however mild the symptoms In these infections the microscope sometimes gives a more reliable indication of gravity than a clinical examination When the patient with grave infection is conscious, co operative, and able to swallow, he may be given oral treatment with the same drugs, and at the same dosage, as for the simple attack (page 74), but even in these cases many physicians prefer to give the first one or two doses by injection for greater assurance of prompt absorption Coma, vomiting, and severe nausca are clear indications for administering by intramuscular or intravenous injection Oral therapy should be substituted for parenteral therapy as soon as the danger is passed, and the patient is able to swallow the drugs and retain them The most effective drugs in these cases are quinine, chloroquine, amodiaqune, and mepacrine (table VIII) Conservative physicians of an older school would probably give this order of precedence, their younger colleagues would be more likely to give pnde of place to chloroquine There would probably be general agreement, however, that chloroquine 13 a better drug than quinine for intramuscular administration (a) Quinine With the exception of mepactine, all the drugs recommended for the treatment of grave falciparum infection may be given either by intramuscular or by intravenous injection We must remember, however, that ·78 CHEMOTHERAPY OF MALARIA TABLE VULT PROPRIETARY PREPARATIONS AND SALTS OF DRUGS RECOMMENDED FOR PARENTERAL TREATMENT IN GRAVE INFECTION (ADULT DOSAGE) Initial carenteral therapy brug Preparation and salts Intramuscular Intravenous Quinine AU Solutions of hydrochloride or Mihy drochloride Chloroquine Resochin Aralen and Nivaquino are available in am poules containing 5% of salt (approxi mately) 1 ml - 30-40 mo of base Single dose not exceed ing 10 ml of 5% solution of salt (300-400 mg of base) Total of god mg of base spaced over first 24 hours Oral the Tapy as soon a9 pos sible Recommended only when there are good cl nical In dicat ons Tor Intravenous Infusion (see text) AM efective blood level la rapidly attained by the sater and more con- Vbnient Intramuscular route Amodlaquine Stable solutions not yet avallable Mepacrime Methanesulfonate Not recommended Single doses not exceed Ing 300 mg Total in frst 24 hours_600-900 mg Oral therapy as soon as possible • Intravenous infus ons in sal ne glucose saline or plasma ** Winckel " recommends concentrated quinine-urethane or quinine antipyrin solutons for Intramuscular Injection They are nearly neutral In reaction and cause less pain than acid solut ons whereas our knowledge of the use of quinine in these circumstances comes of a vast experience over many years, published information on the use of parenteral chloroquine, though very favourable, is still comparatively small For this information we look to the physicians in tropical countries rather than to the experimental laboratories, and they have still to record a sufficient body of rebable evidence Intramuscular or intravenous quinine? There is no unanimity on the relative merits of intramuscular and intravenous quinine in malaria Both methods have received authoritative support, though most experienced physicians today seem to favour the intravenous route from the confused evidence the broad facts and opinions which emerge are (1) that quinine injections should be given only when there are good reasons for them-grave infection, coma, digestive intolerance, defective absorption from the alimentary tract Risks there are, and ·cases do best wca nursed 10 owler! posto 1 the state of the citcuts in that comatose CLINICAL USE OF DRUGS 79 though these nisks cannot be justified for routine treatment, they must be taken when life is at stake, (2) that uztramuscular quinine always produces tissue decTOSIS and may leave fbrotic indurations which last for years, that faulty technique may lead to disastrous crippling, or even to death from tetanus, but that with sensible precautions as to the site of injection and the sterility of equipment and solutions these risks are very small, (3) that intravenous injections of qurine cause a fall za bloodpressure, and carry a smaall risk of venous thrombosis at the site of injection and a remote risk of sudden death when the 1Djection is given too quickly or when there is quinine hypersensitivity or threatening crculatory failure, (4) that quinine acts rather more quickly when injected into the blood stream Iatramuscular quinine should be injected deep into the gluteal muscles An injection site about 3 inches (75 cm) below the centre of the slac crest 15 anatomically safe The skin should be thoroughly cleansed and scrupulous care taken to ensure the sterility of syriage, needle, and solution The ampoules of quinine in concentrated solution prepared by manufacturers for injection are strongly recommended, their sterility is assured, and some of the best of them are especially compounded to gne a solution pearly neutral 1 reaction Single doses should not exceed 1,000 mg (15 grains), and they may with advantage be as small as 500 mg (742 graips), the total dosage over 24 hours should not erceed 2,000 mg (30 grains) With these precavuons, the danger of serious complications is exceedingly small The cardinal principles of intravenous quinine therapy are hugh dilution and slow administration Fatalities have occurred from injections given at the rate often recommended--10 minutes for a 20-ml dose containing 650-1,000 mg (10-15 grains) The drug is far better given as a slow intravenous infusion in a kere of saline, glucose saline, or plasma Strahan 153 bas drawn attention to the efficiency and safety of the continuous intravenous quinine "drip His experience with grave falciparum infection among all nourished prisoners of war suggests that the bazards arising from intravenous quinine therapy are much reduced by this method of admin- Istration Non specific therapy is far more important in these grave falciparum infections than in the simple attack or intravenous transfusion the quinine may be given in normal sahne flucose saline or plasma some physicians recommend the addition of thram ne e percrossery for severe anacstea from heavy destruction or Teamstons of ftesh blood may expencace with a coma team 18 Burma during the second World War tuusfactory ·80 CHEMOTHERAPY OF MALARIA (6) Chloroquine The clinical trials of intramuscular and intravenous chloroquine so far reported, though few in number, have been very favourable The drug is said to be safe and effective when given by intravenous injection or infusion, and it has been suggested that intravenous administration might be the method of choice for the initial treatment of the patient who is seriously ill 180 Rapid injection caused dizziness, nausea, disturbance of vision, and a transient fall in blood pressure, but these effects were almost eliminated when the drug was given by infusion in 500 ml of salıne The dose was 400 mg of chloroquine base Several reports have been published recording satisfactory results following intramuscular injections of chloroquine in single doses up to 300 mg of base The injections were well tolerated, and speedy in their effects 175 176 181 Intramuscular and intravenous injections of chloroquine are alike quickly effective, and in the present state of knowledge it seems that intramuscular administration, from its safety and convenience, will usually be the method of choice The patient's state of fluid balance may well be a deciding factor With obvious dehydration from vomiting, diarrhoea, or sweating, the clinical advantages of the intravenous infusion or continuous "drip” might outweigh other considerations (c) Amodiaquine Since the two drugs resemble one another so closely as regards their antimalarial activity and toxicity, it seems probable that recommendations for the use of chloroquine in severe malaria will apply equally well to amodiaquine It has been reported that amodiaquine is well tolerated when given intramuscularly and intravenously for simple attacks ia doses up to 300 mg of base, 177 178 but there is little information on its merits for parenteral treatment in severe malaria Until clinical experience has more fully confirmed the efficacy and safety of injections, the drug can be used with confidence for the patient who is seriously ill only when it is possible to give it by mouth (d) Mepacrine Mepacrine is a well proved remedy in severe malaria Like all antimalarial drugs, it is best given by mouth Intramuscular injections of the soluble methanesulfonate are very effective and reasonably safe, intravenous administration is inadvisable as the safety margin is small The dose for a single intramuscular injection should not exceed 300 mg nor the total dose exceed 900 mg for the first 24 hours The drawbacks are those ·CLINICAL USE OF DRUGS 81 associated with simple oral therapy, with the added smalt risk of epileptıform convulsions occurnog soon after the injections The convulsions are alarming but they soon pass and seem to have no serious sequelae 3. The relapsing or recrudescent infection When a malana infection has been treated and apparently cured, a recurrence of symptoms means that the treatment has either failed to eliminate all the asexual parasites in the blood, or, having cleared the blood completely, has failed to destroy the persisting forms in the fixed tissues Relapses in falciparum infections are attributed to the persistence of a few asexual parasites in the blood despite treatment, they may occur, though not very often, after treatment with any of the 4-aminoquinolines and allied drugs, particularly quinine Relapses in vivar infections, on the other hand, are thought to be due to secondary exocrythrocytic forms which resist the or schizontocidal drugs and survive treatment they are very common after treatment based solely on the 4-aminoquinolines or allied compounds The presumed origin of relapses in malaria may be represented as follows Pfalciparum Primary ce forms Asexual blood forms causing primary attack and recrudesceaces P vivax Asexual blood forms causing primary attack Primary c-c forms Secondary e-e forms Asexual blood forms causing relapses The treatment of relapses in malaria recognizes these differences of origin Infection due to P falciparum is finally cured by eradication of the asexual blood forms, vivax infections by eradication of both the asexual blood forms and of the secondary exoerythrocytic parasites in the fixed tissues (a) Recrudescing falciparum infection The asexual blood cycle of P falciparum is usually eliminated by the 4-aminoquinolines and similar drugs given at doses appropriate for the acute attack, but falciparum infections do sometimes recrudesce, particularly after quoine treatment They should be treated like any other acute attack, and they may be prevented by a follow up treatment at suppressive dosage with any good schizontocidal drug (See section on after treatment, page 84 ) ·13 80 WAR suscitation by content w (6) Chloroquine The clinical reported, thoug said to be safe infusion, and it be the method seriously ill.180 vision, and a tr eliminated wher dose was 400 r Url : 1:2, is set rolf'!y, to pomemben hoxyca te dras. They ply toué, bet core bene con Invoeren is & vided; it is op tietotis United States is pa!': in some cases treated www Several rep koro Teppis teating a caz de renomen following intrat 300 mg of basc effects 175, 176, 18 Intramuscul quickly effective muscular admi the method of deciding factor sweating, the c "drop" might L (c) Amodiaqui Since the t antimalarial ac for the use of amodiaquine. given intramu 300 mg of bi parenteral tre. fully confirme with confident to give it by r (1) To give ord.-257 race 772 patient cf a prohla reina, TE a chiesto cl sclironocid ref- © To Low-up the ordinary heart o nome, che cosquize, ac odio i doa, warning the face in USE shirt dong is wittdraag. Som one or more intarios is biely, br: STREET pour content the more sery. Trong the primary attack ook nog te hores klizoclocide and learning Telesed on the circumstans, Epseful compromise korreptio IID not be someo bat codex adidil drug; folic: is; suspend s7 trepes": s'acide . and 8-azú (d) Mepacris Mepacrin malarial dru soluble mett venous ad dose for a si total dose e -main of dry si a course of membination will tion:

·CLINICAL USE OF DRUGS 83 this procedure was first suggested by Sinton & Bird #1 in India, who used a combination of pamaquine with quinine This was the standard treat ment for the radical cure of vivax malaria until 1945, when primaquine was synthesized by American investigators in the course of their search for a less toxic drug Primaquine appears to be not only less toxic, but also more active than any of the 8 aminoquinolines yet tested The usual course of treatment lasts 14 days , against refractory infections treated at 1 A- of fontan TABLE IX ADULT DOSAGE OF 8-AMINOQUINOLINES FOR RADICAL CURE IN VIVAX INFECTION brug Dosage Primaquine base or Pamaquine base 15 mg dally for 10-14 days 8-10 mg thrice dally for combined with standard treatment with chloroquine amodiaquine or quintne if an Overt attack la in progress 10-14 days Radical cure of vivax infections with primaquine may also be attempted d S h during latency with primaquine alone—15 mg daily for 14 days 13 Patients taking any of the 8 omsoquinolines should be under daily supervision because of the occasional unpredictable occurrence of acute intravascular haemolysis Cyanosis, abdominal pain, the passage of dark urine, and maybe fever, are the warning signs 4 The dispensary patient The drug or the treatment best adapted to the needs of the malara patient in hospital is not necessarily suitable for the dispensary outpatient Dispensary pati report for fever, they will probably wish to return home, and they may not be seen agaid Treatment must therefore be simple and safe , it must be effective in doses which can be taken at the time of the visit, and it must be cheap The single dose therapy possible with some of the newer drugs meets most of these demands The partial immunity which many of these patients have, particularly in tropical countries, helps the clinical response, and a clinical cure, sometimes a radical cure, may be expected. The most useful drugs are chloroquine (Resochin, Nivaquide, Aralen, or Avloclor), and amodiaquine Recom mended doses are shown in table X ·84 CHEMOTHERAPY OF MALARIA TABLE X SINGLE DOSE THERAPY FOR DISPENSARY PATIENTS Dosage (mg) and age (years) Drug adult over 12 6-12 3-6 under 1 450-800 450 Chloroquine or Amodlaqulne 300 225 600 base 600 base 37 75 400-800 400 300 200 100-150 Single dose treatment with proguanil has proved effective in certain countries and good results have also been reported with pyrimethamine given in the same manner In view of the possibility of drug resistance arising with both proguanil and pyrimethamine, it seems wiser to reserve these drugs exclusively for prophylaxis and suppression Stogle doses of mepacrine sometimes fail, and single doses of quidine usually fail These drugs are hence unsutable for single dose therapy They should be used only when no other drugs are available and then be given over several days The doses recommended for adults are shown in table XI TABLE XI ADULT DOSAGE OF MEPACRINE AND QUININE FOR DISPENSARY PATIENTS Flrat cose at dispensary 8 hours later Dally for the next 3 daya Mepacrine 400 mo Quinine salt-1000 mg (15 gralns) 200 mg 1 000 mg (15 gralna) 300 mg (In one dose) 1 500 mg (23 gralns) (in divided doses) 5 After treatment The primary aim of the treatment recommended for the simple, the grave, and the relapsing infection, is the speedy and safe cure of the attack, with such permanence as is possible with modern drugs given at practical dosage Specific after treatment ensures that the patient is not infective to mosquitos when he leaves hospital, and raises the odds of permanent cure (a) Falciparum infection Radical cure is probable with any of the schizontocidal treatments recommended for the acute attack, but freedom from early relapses may be further assured by a ' follow up” regimen continuing for one month at suppressive dosage chloroquine base-300 mg weekly, amodiaquine ·CLINICAL USE OF DRUGS 85 TI ne base—400 mg weekly, proguanil salt--100 mg daily, or pyrimethamine 25 mg weekly (See also section 3, (a)) In cases where it is considered desirable to sterilize the gametoc, es, specific after treatment is necessary, for the 4-aminoquinolines and similar drug pam for treatment may begin when the temperature has fallen to normal or at the end of schizontocidal treatment, depending on the clinical condition of the patient Delay is perhaps wise if the patient has been seriously ill, for primaquine and pamaquine contribute nothing to recovery and the slight hazard of early combined therapy serves no useful purpose (6) Vivax infection Suppressive after treatment which will give the patient an assured freedom from a recurrence of fever, at least for a time is recommended when the attack has been treated with schizontocidal drugs alone Suitable drugs and doses are pyrimethamine-25 mg weekly, proguanil salt--100 mg daily, chloroquine base-300 mg weekly amodiaquine base–400 mg weekly, or mepacrine--100 mg daily Suppressive therapy may conve puently begin ten days after the completion of treatment for the attack, and continue for two months Whether suppression for a longer period is justified must depend on the circumstances of the patient (See also section 3, (b) and (c)) 6 Blackwater fever In the early stages of blackwater fever, malaria parasites may be found in about half the cases but as haemolysis proceeds they often disappear When parasites are demonstrable in the blood, chloroquine, proguanil, or mepacrine should be given at normal dosage if parasites are not found, suppressive therapy should be maintained into convalescence and a full course given when the clinical condition of the patient justifies it Quinide, pamaquine, and primaquine are contraindicated The Symptomless Carrier The malana carrier who has no symptoms poses a variety of problems for which chemotherapy today often has an appropriate answer, but the answer may be determined more by circumstances than by the status of the individual infection Broadly, three courses are open to cure the infection, to suppress it, or to let it burn out' ·86 CHEMOTHERAPY OF MALARIA 1 The latent vivax infection Curative therapy is desirable if the patient is not exposed to re infection, and if it is practical under the patient's particular conditions of life Prima quine-or, if this is unobtainable, pamaquine-should be given at full dosage without a schizontocide The marginal toxicity of these drugs and the need for supervision are limiting factors If curative treatment is inexpedient, suppression is the best alternative Pyrumethamine, at a dosage of 25 mg once a week, is probably the best suppressive drug, con tinued for at least eight weeks it may sometimes result 10 suppressive cure Sometimes these infections may be left to burn themselves out Most physicians in the tropics have seen highly refractory vivax infections which resist all curative treatment They have then to decide whether to suppress the infections indefinitely, or to leave the patient to work out his own salvation, protected only by schizontocidal treatment for late attacks 2 The “ blood positive carrier Curative therapy or suppression are the alternatives, with gametocyte therapy in addition for "crescent cantiers Curcumstances will decide the appropriate course Curative therapy is indicated when re-infection is unlikely 3 The patient with splenic enlargement Parasites may or may not be demonstrable in the blood of the symptomless patient with an enlarged malarial spleen These patients are usually semi-immunes in endemic areas Suppressive therapy, efficiently applied over a few months, will markedly reduce the size of most malarial spleens Individual Drug Prophylaxis Simple though the concept of malaria prevention by drugs may be, the application of preventive therapy to the varied needs of the person exposed to, or infected with, the malaria parasite is far from simple If an individual wishes to live in a malarıous country and remain healthy, he will ask to be protected against all forms of malaria He may wish for protection to cover a short exposure, with protective therapy nicely timed to the period of risk, or for continuous protection during prolonged exposure , if infected, he will ask to be cured, or at least protected from the clinical manifestations of infection Most of these demands can be met by use of the drugs now available ·CLINICAL USE OF DRUGS 87 1 The General protection suppression of symptoms is perhaps the most useful clinical benefit conferred by regular and prolonged administration of small doses of antimalarial drugs, but it is not the only benefit Some infections are cured, and with particular drugs some are eradicated before they reach the blood stream The term general protection is used here to include suppression, suppressive cure, and causal prophylaxis The drugs commonly used are listed in table XII Given at the dosage recommended these drugs are efficient suppressives in all forms of malaria , and, with the possible exception of quinine, they are all likely to cure falciparum infection within about a month Proguanil and pyrimethamine in addition will usually eradicate falciparum infection at its source in the fixed tissues None of these drugs is likely to eradicate vivax infection with the possible exception of pyrımethamine, which appears to have achieved suppressive cure in some cases against a particular strain of parasite TABLE XII DOSAGE OF VARIOUS DRUGS FOR GENERAL PROTECTION Dosage (mo) and age (years) Drug Interval over 16 11 16 7 10 46 1-3 under 1 100 100 75 50 50 25 dally weekly 300 225 150 100 75 37 Proguanil saltor Chloroquino base Amodlaquino base or Me patrine ** or Pyrimethamine or Qulnlne satt 400 300 200 133 100 100 75 50 25 weekly dally weekly dally 25 25 18 12 500-650 (9-10 grains) 300-500 (5 8 grains) 200-250 (3-4 grains) 130 200 130 65 (2-3 (2 gralns) (1 praln) grans) When protection is required for Imited period only drug administration should be continued for one week after the last day of exposure In the case of proguant and pyrimothamine and for one month in the case of all other drugs Contraindicated in areas where the preva ling malarla is known to be restatant to either * Beo nning 10 days before exposure to Infection with the other drugs listed It is unneces sary to begin the course earlier than the first day of exposure t Recommended only when other drugs are not available of these drups of the drugs listed, proguanil is a causal prophylactic against falciparum infection, and is a good suppressive and an active sporontocide 19 all forms of malaria , its toucity is very low Its tendency to provoke resistance has been discussed in chapter 4 (page 59) In parts of Africa ·88 CHEMOTHERAPY OF MALARIA the doses recommended in table XII have proved insufficient for clinical protection, and double thus dosage may be necessary in such areas Chloroqwne and amodiaquine are powerful suppressants and will achieve suppressive cure in falciparum infection, their toxicity is low, and they do not provoke drug resistance They are inactive against the pre erythrocytic forms of P falciparum and have no inhibitory effect on sporogony Mepacrine resembles chloroquae and amodiaquine in its clinical range but is somewhat less active and not entirely free from toxic side effects Though a thoroughly reliable drug for clinical protection, it can no longer be recommended when the more effective 4-aminoquinolines are available Pyrimethamıne has very much the same activity as proguanıl, but in addition will sometimes achieve suppressive cure with certain strains of P vivax, its toxicity is low Its tendency to provoke resistance has been discussed in chapter 4 (page 58) Quinine, though a useful drug for clinical protection and still fughly regarded in some countries by persons of conservative habit, is less efficient than the synthetic compounds mentioned above and can be recommended only when these are not available Its mode of action resembles that of the 4-aminoquinolines and of mepacrine 2 Causal prophylaxis With some of the modern drugs it is possible to eradicate malaria infections at their source in the fixed tissues, but the application, in the field and in hospital practice, of this radical form of prevention (the causal prophylaxis of James) is restricted by specific differences in the parasites and by the toxicity of some of the drugs The prospects in falciparum malaria are very good , in vivax malaria they are poor, while in malariae and ovale malaria they are not fully known Proguarul and pyrımethamine given at the doses listed in table XII are safe and highly efficient causal prophylactics in falciparum infection, failing only with strains which are resistant to these drugs But all the drugs listed are comparatively inert against the pre erythrocytic forms of P vivax, and causal prophylaxis in vivax infections has been attained only with the 8 aminoquinolines, particularly pamaquine and primaquine Given at about the time of the infecting bite, Pamaquine and primaquine will eradicate infection at the source, but the time of the infecting bite is seldom known and both drugs are too touc for prolonged administration 3 Toxicity of antimalarial drugs Any drug which has to be taken over a long period must be free from serious side effects At the dosage appropriate for prophylaxis, proguanil ·CLINICAL USE OF DRUGS 89 is non toxic, pyrimethamine, given continuously in doses of the order of 25 mg daily, has a reversible depressive effect on the bone marrow, but the dose recommended for prophylaxis is so extremely small that the risk of toxic effects is remote, chloroquine and amodiaquine carry no known risk of any consequence Mepacrine stains the skin and conjunctivae, and sometimes causes a lichenoid dermatitis, while psychoses occurring during suppressive administration have been reported Quinune has a wide margin of safety, but sometimes causes unpleasant cinchonism More detailed information regarding the toxicity of individual compounds is given in chapter 3 All in all, the risks of harmful side effects from prophylaxis based on these drugs are small, particularly when they are assessed in the light of the benefits the drugs confer Only with mepacrine and quinine are these effects ever likely to discourage wide scale use Collective Drug Prophylaxis Malana 10 a community reflects a biological relationship between malaria parasites, their human hosts, and the mosquitos which bring them together Eliminate the mosquitos, or break their contact with man, and malaria disappears most large-scale malana-control projects take advantage of these facts Eliminate the parasites, or interrupt their life-cycle at na tehn1 stances it may be almost complete 1 Principles So long as personal drug prophylaxis is restricted to a few individuals, its effect on the malaria of the community to which they belong will be incidental and probably small But when personal prophylaxis is spread 80 widely as to become collective prophylaxis a new series of effects, cumulative and bighly significant for the community, contribute to the reduction or climination of the seed bed from which the mosquitos derive their infection Persopal drug prophylaxis depends essentially on the interrupuon of the ascxual cycles of the parasite, collective drug prophylaxis brings into play an additional action on gametogony and sporogony, with an interruption in the transmission of infection to mosquitos The factors - ·90 CHEMOTHERAPY OR MALARIA Suppression by chlorogalne Effect on asexual blood cycle Collateral effect on sametocyte reservoir (a) Suppressive cure of falciparum None at first, later, with cessation of at infection tacks, no further production (6) Suppression of vivax and malariae Existing gametocytes destroyed, with cessa infection tion of attacks no further production Catsal prophylaxis and suppression by proguanil Effect on asexual cycles Collateral effect in blood and tissues ont gametocyte reservoir (a) Prevention of falciparum infection No production (b) Suppressive cure of existing falcı parum infection Sporogony inhibited, with cessation of attacks, no further production of game- (c) Suppression of vivax and malariae tocytes infection Since amodiaquine and mepacrine resemble chloroquine in their effects, whilst pyrimethamine in most respects resembles proguanıl, these drugs given efficiently to every member of a closed community mught be expected on theoretical grounds to arrest transmission completely, but practical difficulties limit their effect Communities are seldom isolated from outside sources of infection, and the administration of any drug with unfailing regularity to every member of a community is an exacting task The collateral effects of collective drug prophylaxis on the transmission of infection will hence be related to the epidemiological situation, and to the proportion of the community under regular drug protection 2 Drugs and dosage The continuous administration of a good schuzontocide to a whole population, with dosage intervals related to the potency and persistence of the drug in the body, is theoretically the most effective method of collective drug prophylaxis Initial “mass " or "blanket" therapy at a dosage appropriate for acute attacks is sometimes recommended but is seldom necessary Other methods of administration intermittent "mass " or ** blanket" treatments at intervals of weeks or months, and selective treatments for parasite carriers-have usually been less successful Collective drug prophylaxis based on pamaquine has been generally abandoned, but the possibilities in this field of the more active and less toxic 8 aminoquinoline, primaquine, have yet to be defined For the community, as for the individual, the most suitable drugs are proguanil, chloroquine, amodiaquine, mepacrine, and pyrimethamide Table XIII summarizes the dosage recommended ·(a) that mosquito control is the most successful form of permanent (b) that collective drug prophylaxis is always the method of choice for lations is justified only when more permanent methods are impracticabl (d) that the application of collective drug prophylaxis un stable popi CLINICAL USE OF DRUGS 91 TABLE XHI. ADULT DOSAGE OF VARIOUS DRUGS USED FOR COLLECTIVE PROPHYLAXIS Drug Communities with little Immunity Communities In endemic armles in the feld, etc areas Proguanit e , or 100 mg salt daily 200 mg salt twice a week or 300 mo salt once a week Chloroquine, or 300 mg base once a week 300 ing base once in 1 2 weeks Amodlaquine or 400 mg base once a week 400 ing base once in 1-2 weeks Mepacrine or 100 mg daily 200 mg twice a week or 300 mg once a week Pyrlmethamine, or 25 mg once a week 25 mg once a week Quininec 650 mg (10 pralns) dally 300 mg (5 grains) daily • The doses for children are summarized in table XII . Contraindicated in areas where the prevailing malarla is known to be resistant to either of these drugs A dally dose of 200 mg has been found necessary in parts of Africa & Recommended only when other drugs are not available 3 Indications for collective drug prophylaxis The most successful and indeed the only lasting methods of malana control in stable communities are those which depend on action against the insect vectors There is little or no evidence that malaria can be completely and permanently controlled by drugs But mosquito control is uons malaria control, mobile groups operating in malarious country; or disappointing ·92 CHEMOTHERAPY OF MALARIA Collective drug prophylaxis has important limitations It is likely to be successful only when the regulanty of administration can be assured, and it is justified only when the malaria cangot be controlled at comparable trouble and expense by measures directed against the mosquito Adequate supervision for the administration of drugs is possible only in populations which are fairly concentrated and under some form of discipline, such as armies in the field, labour gangs operating in malarious country, or plantation populations, and it is in these groups that collective drug prophylaxis achieves its most satisfying results The possibilities of collective drug prophylaxis in rural communities are less impressive It can seldom be efficiently applied and is beset with administrative and other difficulties, it remains, however, the quickest method of bringing an epidemic under temporary control 4 Control of epidemics Severe epidemic malaria demands quick action many people are sick, a few maybe are dying, and the immediate situation can be met by drugs alone Collective drug prophylaxis, starting with a loading dose, has here one of its clearest indications The drugs and doses recommended are summarized in table XIV TABLE XIV ADULT DOSAGE OF VARIOUS DRUGS FOR THE EMERGENCY CONTROL OF EPIDEMIC MALARIA Immediate single dose Follow up continuous dosage Chloroquine-600 mg base or Amodlaquina-500 mg base Chloroquine-300 mo base wegkly or Amodlaquine 400 mo base wĐekly or Proguanll_100 mp salt dally or Mepacrine-100 mg dally or Pyrimethamine-25 mg weekly If these drugs are not avallable uso Mepacelne-400 mg . Contraindicated in areas where the prevailing malarla is known to be realstant to ether of these drugs For individuals with fever at the time of examination, a single dose of chloroquine, amodiaguine or mepacrine is sometimes inadequate, further treatment with 300 mg daily for two days is desirable The persons distributing the drugs should ensure that the full dose 13 swallowed and washed down with a drink of water This precaution, a wise one at all times in collective drug prophylaxis, has a special importance during epidemics ·CLINICAL USE OF DRUGS 93 When the malaria is under control, a reduction of the follow up dosage of proguanıl or mepacrine to 200 mg twice a week, or 300 mg once a week, may be considered Drug administration should continue for at least one month-long enough for a suppressive cure of most falciparum infections The likelihood of recrudescent vivax and malariae infections Occurring some weeks after discontinuing the drugs should not be forgotten The emergency distnbution of drugs should not replace or delay other and more lasting forms of control House-spraying with residual insecticides should begin at once, and steps be taken to ascertain the cause of the epidemic Whether drugs should or should not play any part in future control policy must depend on the prevailing conditions and available resources

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·ANNEXES

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·ANNEX I SUNLARY OF SUGGESTED DOSAGE Note The doses suggested ja tus summasy are for adults of approximately 150 lb (70 kg) body weight in general they should be adjusted according to the usual rules for weight and The doses recommended for propbyfaxus and suppression in children are gives ia table XIX. Treatment of chnical attack in non immune subjects (1) Chloroqusnc diphosphate or sulfało 600 mg of basc, 300 mg 6 hours later; 300 mg daily for next 2 days, 0x (2) Amodsaquspe dihydrochloride dikydrate 600 mg of base first day, 400 mg dsuly for next 2 days, OR (1) Mepacrine d hydrochlonde dihydrate 1.000 mg (5 doses or 200 mg) first day. 100 mg tunice daily for dets 6 days, OR (4) Quiosc salt or dihydrochlorido 3,300-3,6 mg (20-30 grans) dasly for 5-7 days Emergency treatment (1) Quioide dihydrochlande 650 mg (10 gTags) sa pormal lunc, glucosa salpe, or plasma, injected intravenously very slowly (not more than 50 mg of salt per minute), repeared in 6 hours if necessary, not more than 3 injections in 24 hours Or admins tered by intravenous dnp, at the rate of 2,000 mg (30 grains) in 24 hours Oral therapy as soon as possible, OR (2) Mepango methano sulfonato givea intramuscularly in single docs not croced Ing 300 mg, total ia first 24 houn, 600-900 mg Oral therapy as won as possible, OR 4 I . the firemnelor route, which is atherally to be preferred on therapy As soon ar possible Radical cure of virar and malartoe infection (1) Pomaquine diphosphate 15 ag of base daily u sagle or dided doses, for 14 days, fciaforced by Handard treatment with a kkizontocida) drug* i pren durlag sa acule attack, OR (2) Panaquíne naphthoate or monobydros Monde 10 og or base tortoe daily far 10-14 days, teraforced by standard treatment with a schimbatocidal drug pyca during a scute attack • Mepartids should sos be diven CORCUTTUG mea as of the Samaganalise drun ·98 CHEMOTHERAPY OF MALARIA Trearment of clinical attack in seme immune subjects (1) Chloroquine diphosphate or sulfate 600 mg of base, single dose; OR (2) Amodiaquine dihydrochlonde dihydrate 600 mg of base, single dose, OR (3) Mepacrise dihydrochloride dihydrate 400 mg, 200 mg 4 hours later, 300 mg daily for next 3 days, OR (4) Quinine sulfate or dihydrochlonde 1,000-1,500 mg (13 23 grains) daily for 2-5 days Prophylaxis and suppression * (1) Chloroquine diphosphate or sulfate 300 mg of base once weekly, OR (2) Proguanil monohydrochlonde * 100 mg daily, or, for partially immune subjects, 300 mg once weekly , OR (3) Amodiaquae dihydrochloride dibydrate 400 mg of base once weekly, OR (4) Pyrimethamine ** 25 mg once weekly, or (5) Mepacrine dihydrochlonde dehydrate 100 mg daily, or, for partially immune subjects, 300 mg once weekly Administration beginning 10 days before exposure to infection, OR (6) Quinine sulfate or dihydrochloride 650 mg (10 grains) daily Recommended only when none of the above listed drugs is available • The prophylactic rcgimen should be continued for one week after leaving an endemic area where proguaml or pyrimethamine has been used and for one month in the case of other drugs ** The use of proguanil or pyrimethamine is contraindicated in areas where resistance to euther of these drugs is known to exist In parts of Africa this dosage has been found insufficient in Nigena, for instance the following scale has been recommended adults, 100-200 mg daily, children 0-1 year 50 mg three to six times weekly 13 years 50 mg daily, over 3 years 100 mg daily ·ANNEX 2 BASE-CONTENT OF TABLETS Each 261 mg tablet of amodiaquine dihydrochloride dihydrate salt contains 200 mg of basc Each 250-mg tablet of chloroquine diphosphate salt contains 150 mg of base Each 500-mg tablet of chloroquine diphosphate salt contains 300 mg of base Each 204-mg tablet of chloroquine sulfate salt contains 130 mg of base Each 136 mg tablet of chloroquine sulfate contains 100 mg of base Each 408 mg tablet of chloroquine sulfate contajs 300 mg of base Each 100mg tablet of mepactine dihydrochloride dihydrate contains 78 5 mg of base Each 360-mg ampoule of mepactie methanesulfonate contains the equivalent of 300 mg of mepacrine dihydrochloride dabydrate Lach 120-mg ampoule of meparine methanesulfonate contatos the equivalent of 100 mg of mepacrine dihydrochlonde dihydrate Each 18 mg tablet of pamaquine naphthoate 10-mg tablet of pamaquine hydrochloride or 9 mg tablet os pasaquine monohydrochloride costume & mg of basc For practical purposes 2 naphthoate = 1 base = 1 mono- or dibydrochloride Each 13 2 mg tablet of primaquinc diphosphate contains 15 mg of basc Each 100 mg tablet of proguanil monohydrochloride contajos 87 mg of base Pyrimethamine is prescribed in the form of basc, not as a salt ·ANNEX 3 PHYSICAL DATA REGARDING SALTS Drug Sal Basecontent (%) Solubility in cold water: (8 per 100 ml) Stable or unstable in aqueous solution Quinino sulfato bisulfato dihydrochloride hydrochlondo 82 84 58-62 79-82 81-83 0 125 10 167 31 stable stablo stable stable Chloroquino diphosphate sulfato hydrochlorido 62 76 S 90 at least 100 33 3 33.3 stablo stable stable Amodiaquino 75 8 at least 20 uostablo dihydrochlorido dihydrato Mopacrino 78 5 23 unstablo dihydrochloride dihydrate dimethanesulfonate 65 5 33.3 stable but should not be stored for any length of time Proguanil monohydrochloride 86 1 stable Pyrimethamine base 100 insoluble - Pangaquino naphthoate monohydrochloride 45 89 5 insoluble at least 20 stable but should be stored under inert gas and in the dark Primaquino diphosphate 37 at least 100 stable but some decomposition may take place on et poiuro to air and Light 10, 20°C -100- ·ANNEX 4 SYNONYMS OF ANTIMALARIAL DRUGS Amodiaqulne CAM-AQI Cam-aqi Camoquin Flavoquino Maquin SN 10731 Pamaquine Aminoquin Beprochen Gamefar Pamaquin Plasmochin Plasmoquino Praequine SN 971 Chloroquine Primaquine SN 13272 • Aralen • Ayloclor • Nivaquino B Resochin Tanakan SN 7618 3377 RP Proguanil Bigumal Chtorguanide Chlonguane Diguanyl Drinupal Guapatol Paludnno Palusid Tirian M 4888 SN 12837 Mepacrine Acnquine Anchin Atabrigo Atatnn Atebris Atebrino Chemiochin Chinang Chinacting Crinodora Enon Haffkino Italchina Malarada Methoquine Metoquina Metoquino Palacan Palusan Quinaonge SN 390 Pyrimetamine Daraprim Maloc de B-W 50-63 Sontoquine Nivaquino A Nivaquine C Santochin Santoquine Soatochin SN 6911 3033 RP • Anles ind Axloclor are chloroquine diphosphate • Nivaquine B, or Nivaquine, Is chloroquine sulfate

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·SELECTED BIBLIOGRAPHY

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·SELECTED BIBLIOGRAPHY Definition of Terms 1 Coveti, O, RUSSELL, PF & SWEL LENGRIDEL, NH Malarla terminology, Geneva, 1953 (World Health Organization Nonograph Series, No 13) Rationale of Malaria Chemotherapy 2. CHRISTOPHERS, S R & FULTON, J D Observations on the retpiratory metabolism of malana parasites and trypanosomes Ant trop Med Parasit 1938, 32 43 75 3 COATNZY, O R & COOPEx WC Recrudescence and relapse in vivax malarla In Proceedings of the Fourth International Congresses on Tropical Medicine and Ma larta, Washington, DC, United States Goveromont Printing Omce, 1948 vol 1, PP 629-639 4 COV, G et al Studies on West African strain of Plas. modium falciparum 11 Tbo efficacy of Paludride (proguanil) as therapeutic a gent Trans roy Soc trop Med Hyg 1949, 42 465-476 3 DAVEY, D G Chemotherapy of malaria Brit med Bull 1951, & 37-46 6 DIAZ DE LEÓN, A Primeros casou de paludismo tratados por un denvado do la rulfanilamida Bol Ofic sanit panamer 1937, 16, 1039-1040 Treatmegt of malaria with sulfonamide compounds Publ HIh Rep (Wash), 1937, 52 1460-1462 7 FAIRLJY, NH et al Chemotherapeutic puppression and pro pbylaus in malana in experimental in vestigation undertaken by medical research Kams in Australia Trons roy Soc trop Med lys 1945, 38, 311 363 8 FAIRLY, NH et Researches on Paludriae (M 4888) in malaria an experimental savestigation undertaken by the LHQ Medical ROsearch Unit (AIF). Cairas, Australia Trans roy Soc trop Med Nye 1946. 40, 105 162 9 FIELD, J W Notes on the chemotherapy of malaria, Kuala Lumpur, Federated Malay States Government Press 1939 (Bulletins from the Insutute for Medical Research Fede rated Malay States, No 2 of 1938) 10 GARNHAM, PCC The mosquito transmission of Plasmodium Inul Halberstaedter & Prowazek, and its pre-erythrocytic developroent in the liver of the rhesus monkey Trans roy Soc frop Afed Uys 1951, 45, 45 52 11 GARNHAM PCC et al Pro-erythrocytic ttsges of human malaria Plasmodium ovale Apreliminary note Brie med 1934, 1, 257 12 GREENBERO, J The potentiation of the anumalanal acui. vity of chlorguande by Aminobenzoic acid competitors / Pharmacol 1949, 97, 28 242 13. GREENTERG. I, BOYD, BL & Jo. SEPHSON [S Synergistic cffect of chlorguanide and sul fadiazine against Plasmodium gallinckrum in the chick J Pharmacol 1943,94 60-64 -103 ·CHEMOTHERAPY OF MALARIA 106 14 GUTTMANN, P & EHRLICH, P 24 SHANNON, J A et al Ueber dio Wirkung des Methylenblau bei The pharmacological basis for the rational Malaria Berl klin Ischr 1891, 28, uso of atabnine in the treatment of malana 953 956 J Pharmacol 1944, 81, 307 330 15 HUFF, C G & COULSTON, F 25 SHORTT, HE et al The development of Plasmodium galana The pre-erythrocytic stage of human maceum from sporozoito to erythrocytic laria, Plasmodium vivar Brit med J trophozoite 1 Infect Dis 1944, 75, 1948, 1, 547 231 249 26 SHORTT, HE et al 16 JAMES S P et al Discussion Synthetic antimalarial reme- The pre-erythrocytic stage of Plasmodium falciparum Brit med J 1949,2, 1006-1008 dics and quinine Trans roy Soc trop Med H) 1932, 26, 105 138 27 SHORTT, HE et al 17. JAMES SP & TATE, P The pre-erythrocytic stage of Plasmodium New knowledge of the life-cycle of malaria falciparum Trans roy Soc trop Med Hyg 1951, 44, 405-419 parasites Nature ( Lond) 1937, 139, 545 18 JAMES, SP & TATE, P 28 SHORTT, HE, BRAY, RS & Cooper, W Exo-erythrocytic schizogony in Plasmodium Further notes on the tissue stages of Plas gallinaceum Brumpt, 1935 Parasitology, modium cynomolgi Trans roy Soc trop 1938, 30 128 139 Med Hyg 1954, 48, 122 131 19 JEFFERY, G M et al 29 SHORTT, H E, GARNHAM PCC Exo-erythrocytic stages of Plasmodium fal & MALAMOS, B ciparum Amer v trop Med Hyg 1952, 1, 917 926 The pre-erythrocytic stage of mammahan malaria Brit med J 1948, 1, 192 194 20 MUDROW, L Klinische und parasitologische Befunde 30 SHORTT, HE, MENON, KP & IYER, P VS und chemotherapeutische Ergebnisse bei der Hühnermalaria Arch Schiffs The form of Plasmodium gallinaceum Tropenhyg 1940, 44 257 275 present in the incubation penod of the infection Indian / med Res 1940, 28 21 RAFFAELE, G 273 276 Un ceppo italsano di Plasmodium elonga 31 SINTON, J A & BIRD, W RIY Malar 1934, 13 332 337 tum Studies in malana, with special reference 22 SCHAUDINN F to treatment Part IX Plasmoquine in the Studien aber krankheitserregende Proto treatment of malaria Indian ) med Res zoen II Plasmodium sivax (Grassi & 1928, 16, 159 177 Felett), der Erreger des Tertianficbers beim Menschen Arb Gesundh Amre( Berl), 32 WOODWARD, R B & DOERING, W E 1902, 19, 169 250 The total synthesis of quinige J Amer chem Soc 1944, 66,849 23 SCHULEMANN, W Synthetic anti malanal preparations Proc roy Soc Med 1932, 25, 897 905 # on Use Venous and in zan med Gaz Individual Compounds ar Qainide 33 CHOPRA, RN, ROY, AC & DAS GUPTA, BM On the concentration of quinine in the ·SELECTED BIBLIOGRAPHY 107 34 COATNEY, GR et al Studies in human malana VII The protective and therapeutic action of quinthe sulfate against St Elizabeth Stran vivax malana Amer J Hyg 1948, 47, 120-134 35 COGGESHALL, LT & CRAIGE, B Old and new plasmodicides In Boyd, MF, ed Afalariology, Philadelphia, Saunders, 1949, vol 2, pp 1071 1113 36 EARLE, DP je et al Studies on the chemotherapy of the human malanas II Method for the quantitative assay of suppressive antroalarial action in falciparum malaria clin Invest 1948, 27, No 3, Part II, pp 75 79 37 SHANNON JA et al Studies on the chemotherapy of the human malanas I Method for the quantitative assay of suppressive antimalanal action ID Vivax malaria J Clin Invest 1948, 27, No 3, Part II, PR 66-74 38 TACOART, J V et al Studies on the chemotherapy of the human malanas III The physiological disposi tion and antimalanal activity of the cin chona alkaloids Jchen Invest 1948, 27, No 3, Part II, PP 80 86 39 WINCKEL, CH WP Quinide injections in malana J trop Med Hyg 1947, 50, 201 203 10 ſection by primaquino administered dunog long term latency Amer J trop Med Hyg 1953, 2, 985 988 4 COOPER, WC et al Studies 19 buman malana XXXI Companson of pnmaquine, isopentaquine, SN-3883, and pamaquino as curative agents against Chesson strain wax ma lana Amer J trop Med Hyg 1953, 2, 949 957 45 DI LORENZO, A et al Korean Wivax malaria IV Curative effect of 15 milligrams of prima quide daily for 7 days Amer I trop Med H) 1953, 2, 983 984 46 EARLE, D P jr et al Studies on the chemotherapy of the human malarias LX Effect of pamaquide on the blood cells of man J clin Invest 1948, 27 No 3, Part II, PP 121 129 47 EDGCOME H et al Primaquine, SN 13272, a new curativo ageat in wax malan12 a preliminary report ) nar Malar Soc 1950, 9, 285 292 48 GARRISON, PL et al Status of primaquine 2 Cure of Korean vvat malana with pamaquine and primaquine J Amer med A53 1952, 349, 1562 1563 49 HOCKWALD, R S et al Status of primaquinc 4 Toxicity of phmaquipe 10 Negrocs J Amer med Ass 1952, 149, 1568-1570 50 JONES, R J et al Korcan visar malaria III Curative effect and toxicity of proaquine in doses from 10 to 30 mg daily Amer / trop Med Hyg 1953, 2 977 982 S1 SCHMIDT I G & SCHMIDT, L JI Neurotoxicity of the s-aminoquinolines III The effects of pentaquine, isopentaquine, primaquine, and pamaquine on the central nervous system of the thesus mon key J Neuropath 1931 10, 231 256 52. THAELER, A D j , ARNOLD, JA ALYTNO, AS A clinical study of primaquint (s N 13,272) in the treatment of malana among Primaquine and other 8 aminoquinolines 40 ALVINO, AS et al Korean Wrax malaria II Curative treat ment with pamaquine and primaquine Amer trop Med Hye 1953, 2, 970-976 41 ALVING, A S, ARNOLD," & ROBIN- SON DH Status of primaquine 1 Mass therapy of rubclinical riyaz malaria with primaquinc J Amer med AJS 1952, 149, 1558 1562 42. CLAYMAN, CB et al Status of primaquine 3 Toxicity of primaquine in Caucasians Amer med Ass 1952, 149, 1563 1568 13 COATNEY, GR et al korean rivax malaria V Cure of the ·108 CHEMOTHERAPY OF MALARIA the Miskito Indians of Nicaragua Amer 61 FINDLAY, GM, MARKSON, L& J trop Med Hy: 1953, 2, 989 999 HOLDEN, J R 53 ZUBROD, CG, KENNEDY, T & Investigations in the chemotherapy of SHANNON, A malaria in West Afnca III Further Studies on the cheraotherapy of the human Javestigations on treatment with qunno malarias VII The physiological dispoend mepacrine Ann trop Med Parasle sition of pamaquib chn Invest 1948, 1944, 38, 201 204 27, No 3, Part II, PP 114-120 62 GORDON, H H, CHRISTIANSON HB See also No 31 & LIPPINCOTT, S W A comparison of quinine and quinacriac in the treatment of the clinical attacks or Mepacrine Vivax malaria Sth med J (Bgham, 54 BAKER, B M & PLATT, D Ala ), 1946, 39, 631 634 Vivax relapso rates following continued 63 HERING, ER, PATT, H M & LLA atabride suppressive medication observa VITT, HJ tions on malaria in an infantry regiment Tolerability studies of some new and Bull Yokns Hopk Hosp 1947, 81, 295 304 malarial drugs Mal Malar Soc 1948, 55 BANG, FB et al 7, 322 329 Treatment of acuto attacks of vivax and 64 LIVINGOOD, CS & DILUAIDE FR falciparum malaria a comparison of ata Untoward reactions attnbutable to ata brine and quinine Bull US Army med brine Amer med Ass 1945, 129 Der 1947, 7, 75 89 1091 1093 56 BRODIE, B B et al 65 LONDON, I M et a! The estimation of basic organic come The effects of quunachae (atabnne) sup pounds in biological material II Estima pression on the course of Pacific vivax uon of fluorescent compounds 7 blol malaria Amer Med 1946 1, 615 620 Chem 1947, 168, 311 318 66 MACHELLA, T E, KIMMELMAN, L J 57 COOPER, WC et al & LEWIS RA Studies in human malaria VIII The pro The intravenous administration of atabnino tective and therapeutic action of quinaende in falciparum malaria Rull US Army against St Elizabeth strain vivax malaria med Dep 1947, 7, 1009 1021 Amer J Hyg 1949, 49, 25-40 67 Most H & HAYMAN, J Mgr 58 ENGEL, GL, ROMANO, J & FERRIS, Relative eficiency of Guidachine (atabriae) E B and quinine in treatment of acute attacks Effect of quinacrin (atabride) on the cen of vivax malana Amerj med Sci tral nervous system, clinical and electro 1946 211 320-324 encephalographic studies Arch Neurol 68 PULLMAN, TN et al Psychiar Chicago), 1947, 58 337 350 Companson of chloroquine, quinacrino 59 FAIRLEY N H et al (atabnice), and quinine in the treatment Ateban suscepubility of the Aitaipe-Wewak of acute attacks of sporozoite induced strains of p falciparam and P virar-A vivax malaria (Chesson strain) prelimi field and experimental investigation by nary report J Clin Invest 1948, 27, LHQ Medical Research Unt, Cairns No 3 Part II. pp 46 50 Trans roy Soc trop Med Hyg 1946 40, 69 TAGGART J V et al 229 273 Studies on the chemotherapy of the human 60 FINDLAY, GM malarias y The antimalanal activity of The toxicity of mepactine in man Trop quidachine Jcion Invest 1948 27, Dis Bull 1947 44 763 779 No 3, Part II, pp 93 97 ·SELECTED BIBLIOGRAPHY 109 70 UNTEED STATES OF AMENCA, ARMONID MEDICAL RESLARCH LABORATORY, FORT KNOX, KY & COMISSION ON TROPICAL DISEASES, ARMY EPIDEMIOLOGICAL BOARD, PREVENTIVE MEDICINE SERVICE, OMCE OP THI SURGEON GENERAL, US ARMY Plasma quigacniat concentration as A fuoction of dosage and cavironment Arch Intern Med 1946, 78, 64-107 71. WATS, RC&GHOSH, BN Quantitative and qualitative methods for detection of Atebrinin urine Rec Malar Sury India, 1934, 4, 367 390 71: WELCH, W J et al Sypbifis of ibe central nervous syslem effect of qumarine hydrochlorde on the incidence of convulsions Arch Derm Sypk (Chicago), 1948, 57, 868 872 See also No 1, 24 Chloroquine and other 4-aminoquloolines 72 ALVIG, A S et al Studies on the chronic toxicity of chloroquine (SN 7618) J Clin Inrest 1943, 27, No 3, Part II, pp 60-65 73 DERBERIAN, DA & DENNIS EW Field experiments with chloroquine diphos. phate Amer trop Med 1948, 28 755-776 74 BERLINEX, RW et al Studies on the chemotherapy of the human maianas VI The physiological disposte tron, antimalanal acuity, and toucity of several derivatives of 4 miboquinoling clor invest 1943, 27, No 3. Part 1}, PP 98 107 75 BRODIE, B Bets! The estimation of basic organic compounds in biological material III Esumauon by conversion to fluotescent compounds y blo! Chem 1947, 168,319 325 76. CHAUDHURI, RN, HAI CHAUDHURI MN & CHAKRAVAITY, NK Chloroquine (SN 7618) in malana Indian Malar 1943, 2, 1 12 71 COATHIY, GR et al Studies in human malaria X The prolective and therapeutic action of chloroquine (SN 7618) against St Elizabeth straia vya maafana Amel J Hyg 1949, 49, 49 99 78 CULWELL, WB et al Studies in human malana XX The intramuscular administration of chloroquine I na! Malar Soc 1948, 7, 335 315 79. Dicourt, P & SCHNEIDER, Traitement curatif du paludisme par divers sels du 3 méthyl-4 (diéthylaminopentyn amino-1-chloroquinoline (Nivaquic) Bull Sec Park exot 1947, 40, 14-17 80 DOBROVOLNY, CG, WHITE, WC & COATNEY, GR Chloroquine and chlorguanide as suppressants of malaria in Guatemala Amer ! trop Med Hys 1953,2 808-845 81 GOLDSMITH, K A controtted fctd trial of SN 7618 S (chloroquune) for the suppression of a lama I Mals/ Inst India 1946, 6, 311 316 82. LOEB RF et al Activity of a sew Buimalarial agent chlo. roquine (SN 1618) J Amer med Ass 1945 130, 1069 1070 83 Most Betal Chloroquint for treatment of acute attacks of vyet malaria 1 Amer med 433 1946 131, 963 947 84 PACKEN HE Experimental field type suppression with SN 7618 (chloroquinc). SN 8137 and SN 12 837 (Faludrine) Snal Afalar Soc 1947, 6 147 154 85 SCHMIDT, LH On the pharmacology of the 4-aminoquino lines in Wixelogle, F Y. ed A survey of antimalariat drugs. 1941-1945, Ano Arbor, Mich, Edwards, 1946, vol 1, PP 94-106 36. SCHNEIDER ). LARAN, M BALTI, M Prophylaxe collective du paludispe par Ia Nivaquine Resultats de l'espérxnce de Chardonaou Tuniske) Bu sos Pozh eror 1943, 41, 189 194 ·110 CHEMOTHERAPY OF MALARIA 87 SCHNEIDER, J & MÉCHALI, D chine (proguanil) as a prophylactic agent Traitement curauf du paludisme Etude Trans roy Soc trop Med Hy8 1949, de l'activité comparée de quatre nouveaux 42, 341-346 dérivés synthétiques Bull Soc Path exo: 96 COVELL, G et al 1948, 41, 274 282 Studies on a West African strain of Plas- 88. YOUNG, M D & EYLES, DE modium falciparum II The efficacy of The efficacy of chloroqutae, quinacrine, Paludride (proguanil) as a therapeutic quiaine and totaquine in the treatment of agent Trans roy Soc trop Med Hyg Plasmodium malanae infections (quartan 1949, 42, 463-476 malaria) Amer trop Med 1948, 28, 962. CURO, PAS, Daver, D G & 23 28 Rose, FL See also No 68 Studies in antimalarial drugs X Some biguanide derivatives as new types of antı Proguanil malarial substances with both therapeutic and causal prophylactic activity Ann 89 ADAMS, AK Det al frop Med Parasit 1945, 39, 208 216 Studies on synthetic antimalarial drugs XIII --Results of a preliminary lnvestiga 97 EARLE, DP jr et al tion of the therapeutic action of 4888 Studies on the chemotherapy of the human (Paludrine) on acute attacks or benign malarias X The suppressive antimalarial tertian malaria Ann trop Med Parasit effect of Paludrine J Clin Invest 1948, 1945, 39, 225 231 27, No 3, Part II, pp 130 133 90 BRUCE CHWATT, L J & BRUCE- 98 EDESON, J FB & FIELD, J W CHWATT, JM Proguanil resistant fafciparum malaria in Antimalarial drugs 19 West Africa with Malaya Brut med J 1950, 1, 147 151 particular reference to proguanil Results 99. GADE, JC & Rose, FL of a survey in Nigeria Brit med J 1950, The estimation of Paludrine in urine Ann trop Med Parasır 1946, 40, 333 336 91 CARRINGTON, H C et al 100 GOOR, W Th VAN & LODENS, J G A metabolite of Paludrine with hugh Clinical malaria prophylaxis with proguaantimalarial activity Nature (Lond), nul Docum neerl indones Morb trop 1951 168, 1080 1950, 2, 62 81 92 CIUCA, M et al 101 INNES, JRM Trials of causal prophylaxis of malaria The effect of intramuscular injection of with Paludin Bull wid Hlth Org 1948, Paludnine and mepacrine in experimental 1, 297 300 animals Ann trop Med Parasit 1947, 93 COOPER, WC et al 41, 46-49 Studies in human malaria XXVIII Ob 102 JOHNSTONE, RDC servations on the use of chlorguanide Relapsiog beoign tertian malana treated against the Chesson strain of Plasmodium with Paludrine Lancet, 1946, 2, 825 826 Vivar J nai Malar Soc 1950, 9, 366 376 103 JONES, R J et al 94 COVELL, G et al The therapeutic effectiveness of large doses Paludrine (proguadul) in prophylaxis and of Paludnae in acute attacks of sporozoite treatment of malarial infections caused induced vivax malaria (Chesson strain) by a West African strain of P falciparum Clin Invest 1948, 27, No 3, Part II, Bnt med J 1949, 1, 88 91 95 COVELL, G et al 104 LINTS, H A et al Studies on a West African strain of Plas. Studies in human malaria XXII PIO modium falciparum The efficacy of Palu longed suppression of Chesson straja vivax Pp 51 55 ·SELECTED BIBLIOGRAPITY malaria by the weekly admoustration of chlorguanide or chloroquine J nar Molar Soc. 1950, 9, 50-58 105. MACXERRAS, M J & LRCOLE, Q N Observations on the action of Paludnine on malanal parasites Trans roy Soc trop Med Hyg 1943, 41, 365-376 106. MAEGRAITH, B G et al Tbc absorption and ercretion of Paludnice in the human subject Ann frop Med Parasit 1946, 40, 493-506 107. MALGRAITH, B et af Paludrine in the treatment of malana Brit med J 1946, 1, 903 905 108 MON, JF Results of an investigation of the thera peutic action of Paludnine and pamaquin on acute attacks of benign tertian malania Trans roy Soc trop Med Hye 1948, 41, 657-662 109 MULUCK, KB & GUPTA, JC Intravenous Paludnine in malaria Indian med Ga: 1947, 82, 666-663 110 RAMAKRISHNAN, S P et al The effect of single and multiple doses of Paludnine upon Plasmodium fulciparum Amer J Hyg 1952, 55, 239-245 111 RAY, AP Prophylactic use of Paludnine in a tea estate Indian J Mular 1948, 2, 35-66 112. SNUTE, P G & MARYON, M The gametocytocidal action of Paludrine upon infections of Plasmodium falciparum Parasitology, 1948, 38, 264-270 113 WILSON, T, MUNRO, DS & RICILARD, DR Proguanil resistance in Malayan strains of Plasmodium ziyar Brit med 1 1952, I, 564-568 See also No 8 115 BRUCE CHHATT, L T & ARCHIBALD, HM Field trials of new antimalarials in West Afnca Brit med J 1953, 1, 539-541 116. COATNEY, GR et al Studies in buman malana XXXII The protective and therapeutic effects of pyrimcthaminc (Darapnim) against Chesson straia vivar malaria Amer J trop Med Hyg 1933, 2, 777 787 117 COVELL, G, SHUTE, PG & MARYON, M Pynimetamine (Daraprim) as a prophy. lactic agent against a West African strain of P falciparum Brt med 1 1953, 1. 1081-1083 118 COVELL, G SHUTE, P G & MARYOY, M Pyrimethamine (Darapnm) in the treat meat of vivax malara Brit med J 1953, 2. 258 259 119 Foy, H & KONDI, A Effect of Darapum on the gametocytes of Plasmodium falciparum Trans roy Soc trop Med Hyg 1952, 46, 370 120 GOODWT LG Daraprim (B W 50-63a new antimalanal trials in human volunteers Brit med 1 1952 1, 732 734 121 Goodwry LG Daraprim--Clinical trials and pharmacol ogy Trans Toy Soc trop Aled H78 1952, 46, 435-495 122. HERNANDEZ, T et al Studies in human malana XXXIV Acquired tesistance to pynimethamine (Daraprim) by the Chesson strain of Plasmodium wirax Amer 1 trop Med Hy8 1953, 2, 797 804 123 HTCHINGS, G H Daraprim as an antagonist of folic and folinic acids Trans roy Soc trop Med H) 1932, 46, 467-473 123. JASWANT SAG et al Acquired resistance to proguanil in Plus. motion knowles Trans roy Soc. trop Med Hyr 1952, 46, 639-649 Pyrimethamine 114 ARCIBALD, HIM Preliminary field tnals on a new schizonticide Brir med ) 1951, 2, 821-82!

·112 CHEMOTHERAPY OF MALARIA 123b JASWANT SINGH et al Studies on the Nuri strain of P knowlesi V Acquired resistance to pyrimethamine Indian / Malar 1954, 8, 187-195 124 MYATT, A V, HERNANDEZ, T & COATNEY, GR Studies in human malaria XXXIII The toucity of pyrimetharine (Daraprm) in man Amer J trop Med Hyg 1953, 2, 788 795 125 ROBERTSON, G I , DAVEY, D G & FAIRLEY, NH Cross resistance between Daraprim and proguanil Brit med J 1952, 2, 1255- 1256 127 SCHMIDT, L H & GENTHER, CS The antiralanal properties of 2,4-diamino- 5 p-chlorophenyl 6-ethylpytımıdınc (Dara pnm) J Pharmacol 1953, 107, 61 91 128 SCHMIDT, LH, HUGHES, H B & SCHMIDT, 1 G The pharmacological properties of 2,4 diamino-5-p chlorophenyl 6 ethylpyrımı dine (Darapnm) J Pharmacol 1953, 107, 92 130 129 SCHNEIDER, J, CANET, ) & Du POUX, R Traitement curatif du paludisme par une 2-4 diamidopyrimidine Premiers résul tats Bull Soc Path exot 1952, 45, 33-43 130 VINCKE I H Note préliminaire sur la prophylaxie me dicamenteuse par Daraprim en milieu Tural Ann Soc delge Med trop 1952 32, 91 99 126 ROLLO IM Daraprim-experimental chemotherapy Trans roy Soc trop Med Hyg 1952, 46, 474-484 Drug-Resistance in Malaria 131 ADAMS, A RD & SEATON, DR golleraceum and its relation to other anti Resistance to Paludrise developed by a malanal compounds Parasitology, 1950, strain of Plasmodium falciparum Trans 40, 163 174 roy Soc trop Med Hyg 1949, 42, 314-315 137 BISHOP, A & MCCONNACHIE, E W 132 BISHOP, A & BIRKETT, B Cross resistance between sulphanılamide Acquired resistance to Paludrme in Plas and Paludrine (proguanil) in a strain of modium gallinaceum, acquired resistance Plasmodium gallinaceum resistant to sul and persistence after passage through the phanılamide Parasitology. 1950, 40, mosquito Nature (Lond ), 1947, 159, 175 178 884 885 138 BISHOP, A & MCCONNACHE, E W 133 BISHOP, A & BIRXETT, B Failure to produce resistance to chloro Drug resistance in Plasmodium gallina quine in Plasmodium gallinaceum in chicks ceum and the persistence of Paludrine Parasitology, 1952 42, 52 56 resistance after mosquito transmission 139 BISHOP, A & MCCONNACHTE, E W Parasitology, 1948, 39, 125 137 Pamaquin resistance in a strain of Plasmo- 134 BISHOP, A & MCCONNACHIE, E W dium gallinaceum and its relationship to Resistance to sulphadiaziao and Palu other antimalariat drugs Parastrology drine in the malaria parasite of the fowl 1952, 42, 57 64 (P gallinaceum) Nature (Lond), 1948, 140 BOYD, MR 162, 541 543 On strains or races of the malaria para 135 BISHOP, A & MCCONNACHIE, E W sites Amer ſtrop Med 1940 20, 69 80 The stability of Paludnine resistance 1a 140a. CANET, J Plasmodium gallinaceum in the absence of Proguanil resistance dunog mass prothe drug Parasitology. 1950 40, 159 162 phylaxis of hyperendemic P falciparum 136 BISHOP, A & MCCONNACHIE, EW malaria in Indo China Bull Soc Path Sulphadiazine resistance in Plasmodium exof 1953, 46, 230-245 ·SELECTED BIBLIOGRAPHY 113 1400 CHAUDHURI, RN & RAI CHAUD- HURI, MN Falcipanım infection refactory to Paludnpe Indian Molar 1949, 3, 365 369 141. COOPER, WC, COATNEY, GR & IUBODEN, CA Studies in human malana XXIII Acquired resistance to chlorguanide in the Chesson strain of Plasmodium pirar J nal Malar Soc 1950, 9, 59 66 142. FLETCHER, W Notes on the freatment of malarla with the olhalolds of cinchona, London, Balo & Danielsson 1923 (Studies from the Instituto for Medical Research, Federated Malay States No 18) 143 FULTON, J D & YORKE, W Studies in chemotherapy XXIX The development of plasmoquine resistance in Plasmodium knowlesi Ann trop Med Parasli 1941, 35, 233 239 144 FULTON JD & YORKE W Studies in chemotherapy XXXII -Further observations on plasmoquine-TC375 tance in Plarmodium knowlesi Ann trop Med Parasit 1943, 37, 41-47 141. GILROY, A B Proguanil resistant Plasmodium falciparum in Assam Ann tror Med Parasit 1952 46 121 126 145 GREENDERO, 1 Inhibition of the antimalanal activity of chlorguanide by pteroylglutamic acid Proc Soc exp Biol (NY), 1949, 71, 143a. JASWANT SINGH et al Drug resistance of prevrythrocytic forms of Plasmodium gallinaceum Brumpt, 1935 Indian J Melar 1952, 6, 457-464 1486 JASWANT SINGH et 1 Development of resistance to pytuaeth. amide in P cynomolgt Indian / Malar 1953, 7, 357 368 149 JONES, SA Experiment to determine if a proguanil resistant strain of P falciparum would respond to largo doses of pynmethamino Brit med 1 1953, 1. 977 150 JONES, SA Resistance of P falciparum and P malariae to pynmethamine (Daraprim) following mass treatment with this drug A preli- Minary note E fr med J 1954, 31, 47-49 151 KNOPPERS, A Th Acquired resistance (twofold) to quinine in Plasmodium fallnaceunt Nature (Lond), 1947, 160, 606-607 152. KOSSIAXOFT, MG De la propnéte que possèdent les microbes de accommoder aux milieux antiseptiques Ann Inst Pasteur 1887, 1, 465476 306 308 146 HAWKINO F & PERRY, W L M Resistance to proguanil (Paludnine) in a mammalian malana parasite (Plasmodium cynomoign Lancet, 1943, 2, 850 147 HAWKINO, T & THURSTON I P A strain of monkey malaria (Plasmodium cynomoign made resistant to proguansl (Patudnpe) Trons roy Soe trop Med Hyr 1951, 41 695 701 143 JAMES SP, Nicol, W SHUTT, PG A study of Induced malignant tertan mafacia Proc roy Soc Aled 1932, 2s, 1153 1186 153 LOURIE, EM Studies on chemotherapy in bird malana IV -Failure to promote drug resistance in Plusmodium cathamerium by prolonged administration of quinine or Plasmochin Ann frop Med Parasit 1935, 29, 421-433 154 MCCONNACHE, CW Latent infections in avian malaria in relation to the production of drug resistance Parasitology, 1950 41, 110-116 155 MASSANT, J Sensibilité et adaptation des organismes a la concentration des solutions salidas Arch Biol (Paris) 1889 9 515 570 156 NAUCX, EO Chemotherapeutische Versuche bei Afenmalaria (Pl knos kui) Arch Schinter Tropening 1934 38 313 326 ·114 CHEMOTHERAPY OF MALARIA 415 157. ROLLO, IM 166 THOMPSON, P E et al A 2 4-diamino pyritardino in the treat Os the ability of Plasmodium lophurae to ment of proguanil resistant laboratory acquire resistance to chlorguanide, Camomalarial strains Nature (Lond), 1951, qun and chloroquine infect Dis 1948, 168, 332 333 83, 250 255 158 Rouio, I M 167 WALKER, AT & REID, JA Daraprim resistance in experimental mala Resistance to proguadil in the gametocytes nal infections Nature (Lond), 1952, 170 and pre-erythrocytic forms of Plasmodium falciparu Trans Toy Soc Top Med 159 ROLLO, I M, WILLIAMSON, J & Hys 1953, 47, 580 LOURIE, EM 168 WILLIAMSON, J, BERTRAM, DS & Acquired Paludrine resistance in Plasmo LOURJE, EM dium gallinaceum II --Failure to produce Effects of Paludrine and other antimala. such resistance by prolonged treatment of rials Nature (Lond), 1947, 159, 885 886 latent infections Ann trop Med Parasys 1943, 42 241 248 169 WILLIAMSON, J & LOURIE, E M 160 SCHMIDT, LH et al Acquired Paludrine resistance in Plasmo- Development of resistance to chlorguanide diunt gallınaceum I--Development of resistance to Paludnine and failure to (Paladrinc) detag treatment of infections with Plasmodium cynomolgi J Pharmacol develop resistance to certain other anti 1949, 95, 382 398 malarials Ann trop Med Parast 1947, 41, 278 291 161 SEATON, DR Failure to induce chloroquine-resistance in 170 WILSON, T & EDESON Y FB Plasmodium gallinaceum Anh trop Med Treatment of acute malaria with pynime thamine Parasit 1951, 45 99 100 Bret med J 1993, 1, 253 255 162 SEATON DR & ADAMS ARD 171 WILSON, T MUNRO, DS & Acquired resistance to proguanit in Plas RICHARD, DR modium falciparum Lancet 1949 2, Proguanil resistance in Malayan strains of 323 324 Plasmodium wyor Brut med 1952, 1, 564 568 163 SEATON DR & LOURIE, E M Acquired resistance to proguanil (Palu 172 WORK, T S & WORK, E drine) in Plasmodium yavax Lancet 1949 The basis of chemotherapy, Edinburgh, 1, 394-395 Oliver & Boyd, 1948 164 SHANNON JA et al 173 YUDKIN J Studies on the chemotherapy of the human Ongin or acquired drug resistance in bacmalarias I Method for the quantitative tena Nature (Lond), 1953 171, 541 546 assay of suppressive antimalarial action in vivax malaria J Clin Invest 1943, 27, See also No 8, 37, 59, 98, 100, 105, 110, No 3 Part II pp 66 74 112 122, 125, 127 165 SINGH, J et al Daraprim (50 63) in situan malana Indian J Malar 1951, 5, 531 540 Clinical Use of Antimalarial Drugs 174 GREAT BRITAIN, COLONIAL MEDICAL 175 JELLIFFE, D B & JELLITE, E FP RESEARCH COMMITTEE, MALARIA SUBCOM The out patient treatmept of malaria with MITTEE single dose intramuscular chloroquine in Use of antimafanal drugs Recommen a hyperendemic area in West Afnca Trans dations Lancet 1954 1, 1340-1342 roy Soc trop Med Hyz 1953, 47, 235 238 ·SELECTED BIBLIOGRAPHY 176. Mon, W Parenterale Resochugtherapie bei den ver Khiedenen Malariaformen 2 Tropenmed Parasir 1953, 4 137 153 IIS 177 PAYNE, E H et al Intravenous amodiaquin (Camoquin) in naturally acquired and induced malana Amer I trop Med 1951 31, 698 702 178 PAYNE EH. SHARP, AE & NICKEL, KC Parenteral use of Camoquin bydrochlonide as an anumalana! Amer 1 trop Med 1949 29, 353 368 180 SCOTT, V Single intravenous injections of chloroquine in the treatment of falaparum ma Laria touc ind immediate therapeutic effects in 110 cases Amer trop Med 1950, 30, 503 510 181 SPICENALL, CO, TERRY, L L & COATNEY GR The treatment of falciparum malana wib intramuscular chloroquine Amer J med Sc 19.49 218 37+377 182. STRAHAN, Y H Quoioe by continuous intravenous dnp in the treatment of acute falciparum ma laria Trans roy Soc trop Med Hys 1948, 41, 669-676 See also No 31 39 40, 43, 44, 50, 116, 117 179 RANSOME, GA Notes on the management of cases of cerebral malaria Proc Alumni Ass King Edw VII Coll Med 1948, 1 23 29

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·INDEX

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·INDEX Absorption and elimination of drugs, see under specific drugs Acndino derivatives, see 9-Aminoacri dines Activity of drugs, see under specific drugs Acute infection, simple, treatment, 74-77 Administration of drugs, see under specific drugs After treatment, 84-85 falciparum infection, 84 Vivax Infection, 85 Age and body-weight in dosage, 73 9-Aminoacridines, chemical structure, 18 See also Mepacrine 4-Aminoquinolines, activity, 71 chemical structure, 19 dosage, grave infection, 78 almplo acute infection, 74 historical aspects, 13 uso la recrudescing falciparum fec. tion, 81 See also Amodraquine, Chloroquino Soo toquine 8-Aminoquinolines, activity, 71 chemical structure, 17 for radical cure of vivax Infection, B2 83 historical aspects, 14 use in relapsing vivax Infection, 82 See also Pamaquine, Pnmaquine Amodisquine, activity, 71 administration, route, 80 advantages over mepatrine, 43 base-content of tablicts, 99 chemical structure, 19 dosage, suggested, rummary, 97 98 for collective prophylaxis, 91 for emergency control of epidemics, 92 Arnodiaquine (continued) for general protection, 87, 88 in grave infection, 78, 80 in simple acute infection, 74, 76 res.stance, 58 salts, physical data, 100 single-dose therapy for dispcasary patents, 84 synonyms, 101 Antibiotics, antimalarial activity. 23 Antimalarial drugs, absorption and climsnation, see under specific drugs action on life-cycle of parasite, 26-27, 70 activity, see under specific drugs administration, see under specific drugs chemical structure, 16-23 clinical use, 69 93 concentration in body fluida, factors affecting, 27 28 cross-resistance, 64-65 bistoncal review, 10-14 pharmacology, 27 28 resistance, 54-68, 73 spelling of names, 10 tynonyms, 101 synthetic, evolution, 11 toxicity, see ander specific drugs types forming basis of present-day therapy, 71 Asexual blood forms, see Erythrocytic forms, asctual Asexual parasitaemia. effect of quinine on, 33 Base of salt, confusions in dosage, 73 Base-content of tablets, 99 recommended use is expressing dosage, 73 Basic drugs for present-day therapy, 77 119 ·120 CHEMOTHERAPY OF MALARIA Biguanides, activity, 71 Collective drug prophylaxis (continued) chemical structure, 20 principles, 92 See also Proguanıl role in control of epidemics, 92 Biological approach to research, 23 31 Confusions of dosage, 72-74 Blackwater fever, malaria parasites in Control of epidemics, role of collective early stages, 85 drug prophylaxis, 92 Body weight and age in dosage, 73 Cross resistance between antimalarial drugs, 64-65 Carriers, symptomless, see Symptomless Cure, definition, 9 carriers radical, malanae infection, 97 Causal prophylaxis, 88 Vivax infection, 82 83, 97 Chemical approach to research, 15-23 Chloroquine, 43-46 Diaminopyrimidines, chemical structure, absorption and elimination, 44 21 activity in human malaria, 43, 71 See also Pyrimethamine administration, route, 78, 80 advantages over mepacrine, 43 Dispensary patients, mepachine and quibase-content of tablets, 99 nine dosage, 84 chemucal structure, 19 recommended treatment, 83 84 contraindications, 44 single dose therapy, 84 dosage, suggested, summary, 97-98 Dosage, age and body weight in, 73 estiration in body fluids, 45-46 confusions, 72 74 for collective prophylaxis, 91 summary, 97-98 for emergency control of epidemics, 92 clinical attack, 97, 98 for general protection, 87, 88 emergency treatment, 97 in grave infection, 77, 78, 80 prophylaxis and suppression, 98 in simple acute infection, 74, 76 radical cure, vivax and malariae plasma concentrations during treatinfections, 97 ment, 44 Drug resistance, 54 68 resistance, S7 acquired by previous drug contact, 56 salts in common use, 46 definstion, 55 physical data, 100 in geographical strains, 56 single-dose therapy for dispensary pa. natural, within species, 55 tients, 84 nature, 67 synonyms, 101 origin and mechanism, 65-66 toxicity, 44 Cinchona, bustorical aspects, 10 relation to confusions of dosage, 73 Cinchona alkaloids, chemical structure, 16 See also under specific drugs See also Qupine Drugs, antimalanal, see Antimalarial drugs Cipchona mixtures, 36 Clinical attack, con immune subjects, Emergency treatment, suggested dosage, 97 suggested dosage, 97 Epidemics, control, role of collective drug sem immune subjects, suggested dosage, prophylaxis, 92 98 Erythrocytic forms, asexual, drugs acting Clinical cure, definition, 9 on, 27, 32, 37, 39, 43, 47, 51 Clinical use of antimalarial drugs, 69 93 resistance to proguanıl, 47, 59 60 Collective drug prophylaus, 89-93 Exoerythrocytic forms, primary, see Predosage of various drugs, 90 92 erythrocytic forms dıcations, 91 resistance to proguanil, 59 limitations, 89 Secondary, drugs acting op, 27, 37, 31 range, 57 ·INDEX Falaparum infection after treatment 84 Fever in acute malana effect of quinine on 33 121 Gametocytes drugs acting on 21 37 39 43, 49 52 resistance to proguanil 60 Gamclocytocide defution 9 General protection dosage of various drugs 87 91 98 Grave infection treatineat 77-81 Mepacrine (continued) in ample acute infection 74 76 plasma concentrations dunng treatment 40-41 resistance 57 salts in common use 42 physical data 100 synonyms 101 toucity 40 Metachlondine chemical structure M scellaneous compounds antionalariat activity 23 Hastoncal review of antimalarial drugs 10-14 Naphtboquinoncs activity against avian plasmodia 22 chemical structure 22 mmunity factor effect on dosage 72 necessly for rescarch on 29 dvidual drug prophylaxus 86-89 Causal 88 for general protection 87 de-effects 88 89 Organometallic compounds antimalarial activity 22 23 Lapinone, chemical structure 22 suppress ve action against viyat mala ria 22 Life-cycle of malana parasite 23 26 action of drugs on 26 27 70 development in blood stream and us fucs 24 25 Load ng dose in treatment of acute simple infection 75 Malaria parasite see Parasite Malarae infection radial cure 97 Mepacrine 39-42 absorption and cl mination 40 actnity in human malaria 39 71 administration route 78 80 advantages over quinine 40 hase content of tablets 99 chemical structure 18 contraindications 40 dosage suggested summary 97 98 ciumaton ta body fluids 41 for collective prophylaus 91 for dspensary patients 84 for emergency control of cridemas 92 for fencral protection 87 88 hustoncal aspects 12 13 in mave infection 77 78 80 Pamaquine activity 71 base-content of tablets 99 chemical structure 17 dosage rad cal curt of virar infection 83 suggested summary 97 98 hustorical aspects 12 13 tes stance 37 uits physical data 100 synonyms 101 Parasite life-cycic 3 27 70 res stance to drugs see Drug resistance response of different strains to drugs 28 29 72 See also under specific forms of parasite Pharmacology of anumalanal drugs 2723 Plasma concentrations se wnder specific drugs Plasmod um metabolism cffect of drugs on 30 Pre-erythrocytx forms demonstration in monkeys livet 24 25 drugs acting on 26 37 47 SI Primaquinc 37 39 absorption and elimination 38 activity in buman malaria 37 71 base-contcal or tablets 99 chem cal structure 18 contraindkalions 38 dosage nada al cure of virzt Infeston ·120 CHEMOTHERAPY OF MALARIA Riguanides, activity, 71 chemical structure, 20 See also Proguanil Biological approach to research, 23 31 Blackwater fever, malaria parasites in early stages, 85 Body weight and age in dosage, 73 Collective drug prophylaxis (continued) principles, 92 role in control of epidemics, 92 Confusions of dosage, 72-74 Control of epidemics, role of collective drug prophylaxis, 92 Cross-resistance between antimalarial drugs, 64 65 Cure, definition, 9 radical, malatiae infection, 97 vivax infection, 82 83, 97 Carriers, symptomless, see Symptomless carriers Causal prophylaxis, 88 Chemical approach to research, 15 23 Chloroqume, 43-46 absorption and elimination, 44 activity in human malaria, 43, 71 administration, route, 78, 80 advantages over mepacrine, 43 base content of tablets, 99 chemical structure, 19 contraindications, 44 dosage, suggested, summary, 97-98 estimation in body fluds, 45-46 for collective prophylaxis, 91 for emergency control of epidemics, 92 for general protection, 87, 88 in grave infection, 77, 78, 80 in simple acute infection, 74, 76 plasma concentrations during treatment, 44 resistance, 57 salts in common use, 46 physical data, 100 single dose therapy for dispensary patients, 84 synonyms, 101 toxicity, 44 Cinchona, historical aspects, 10 Cinchona alkaloids, chemical structure, 16 See also Quinine Cinchona mixtures, 36 Clinical attack, non-immune subjects, suggested dosage, 97 sem immune subjects, suggested dosage, 98 Clinical cure, definition, 9 Clinical use of antimalarial drugs, 69-93 Collective drug prophylaxis, 89 93 dosage of various drugs, 90 92 indications, 91 limitations, 89 Diaminopyrimidines, chemical structure, 21 See also Pyrimethamine Dispensary patients, mepachine and quiune dosage, 84 recommended treatment, 83-84 single dose therapy. 84 Dosage, age and body weight 19, 73 confusions, 72 74 summary, 97 98 clinical attack, 97, 98 emergency treatment, 97 prophylaxis and suppression, 98 radical cure, vivax and malariac infections, 97 Drug-resistance, 54 68 acqwred by previous drug contact, 56 definition, 55 10 geographical strains, 56 natural, within species, 55 nature, 67 origin and mechanism, 65 66 range, 57 relation to confusions of dosage, 73 See also under specific drugs Drugs, antimalanal, see Antimalarial drugs Emergency treatment, suggested dosage, 97 Epidemics, control, role of collective drug prophylaxis, 92 Erythrocytic forms, asexual, drugs acting on, 27, 32, 37, 39, 43, 47, 51 resistance to proguanıl, 47, 59 60 Exoerythrocytic forms, primary, see Preerythrocytic forms tesistance to proguanıl, 59 Secondary, drugs acting on, 21, 37, 51 ·INDEX 123 Synonyms of antimalarial drugs, 101 Teros, definition, 9, 55 Therapeutic policy, 70-71 Toxicity of drugs, see ander spectfic drugs Treatment, grave infection, 77-81 relapses, 81 82 simple acute infection, 74-77 Single-dose therapy for dispensary patients. 84 Sontoquine, chemical structure, 19 historical aspects, 13 synonyms, 101 Sporogonic forms, drugs acting oo, 27 Sporontocide, definition, 9 Strain of parasite, relation to dosage, 72 Sulfonamides, antimalanal activity, 19-20 See also Metachlondine Suppression, definstion, 9 1uggested dosage, 98 Symptomless carriers, 85 86 and splenic enlargement, 86 "blood positive", 86 of latent vivax infection, 86 Syaergism, 29 30 Vivax infection, after-treatment, 85 radical cure, 82 83, 97 suppressive action of Lapisone on, 22 Weight-dosage, see Age and body-weight in dosage Young's formula for body weight dosage, 73 ·122 CHEMOTHERAPY OF MALARIA Primaquine (continued) Pynmethamine (continued) suggested, summary, 97-98 salts ia common use, 39 Tesistance, 58 synonyms, 101 physical data, 100 toxicity, 52, 89 synonyms, 101 toxicity, 38 Pyrimidines, activity, 21 chemical structure, 15 Proguanil, 46 S1 See also Pyrimethamine absorption and elimination, 49 activity in human malaria, 47-49, 71 Quinine, 32-37 base-content of tablets, 99 absorption and elimination, 34 chemical structure, 21 activity in human malaria, 32, 71 comparison with quinine for treatment and ciachona mextures, 36 of acute malaria, 48 administration, route, 78-79 contraindications, 49 contraindications, 34 dosage, suggested, summary, 97-98 detection in unde, 36 estimation in body iuids, 49 dosage, suggested, summary, 97 98 evolution, 14 effect on asexual parasıtacmua, 33 for collective prophylaxis, 91 effect on ſever in acute malaria, 33 for general protection, 87 for collective prophylaxis, 91 plasma concentrations during treatment, for dispensary paticats, 84 49, 50 for general protection, 87, 88 resistance, 59 64 In grave infection, 77, 78 development in schizogonic blood in simple acute infection, 74, 76 forme, 47 isolation, 11 prevention, 63 plasma concentrations during treatment, range, 59 35 rate of development, 60 tesistance, 57 recognition, 62 salts in common use, 37 spread under field conditions, 61 physical data, 100 stability, 61 toxicity, 34 salts in common use, 50 physical data, 100 Quinoline derivatives, see 4-Aminoquinosynonyms, for lides , 8-Aminoquinolines toxicity, 49 Radical cure, definstion, 9 Prophylaxis, collective drug, see Collec malariae infection, 97 tive drug prophylaxis vivax infection, 82-83, 97 definition, 9 dosage of various drugs, 87, 90.92, 98 Recrudescing infections, see Relapses indivdual drug, see Individual drug Relapscs, causes, 81 prophylaxis treatment, faciparum infection, 81 Pyrimethamine, 51-53 Vivax infection, 82 absorption and elimination, 53 Research, biological approach, 23-31 activity in human malaria, 51-52, 71 chemical approach, 15-23 chemical structure, 21-22 contraindications, 52 Resistance to antimalarial drugs, see Drug. dosage, suggested, summary, 97-98 resistance effect on parasite rate, 51 effect on sporozoite-rate, 52 Salts of antimalanal drugs, physical data, for causal prophylaxis in falciparum 100 infection, 88 Schizontocides, definition, 9 for collective prophylaxis, 91 for general protection, 87, 88 Sexual forms, see Gametocytes

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