Prospective Double-Blind Trial of Two Different Doses of Mefloquine Plus Pyrimethamine-Sulfadoxine Compared with Pyrimethamine-S

Bulletin ofthe WorldHealth Organization, 63 (4): 731-737 (1985) © World Health Organization 1985

Prospective double-blind trial of two different doses of mefloquine plus pyrimethamine-sulfadoxine compared with pyrimethamine-sulfadoxine alone in the treatment of falciparum malaria

D. BOTERO M. RESTREPO,2 & A. MONTOYA2

This double-blind study is based on the treatment of 75 adult male patients suffering from Plasmodium falciparum malaria in Medellin, Colombia, a city in which there is no malaria transmission. The patients, who came from regions with high resistance to antimalarials, were divided into three groups receiving single-dose treatment asfollows: a combination of 280 mg mefloquine, 800 mg sulfadoxine and 40 mg pyrimethamine; a combination of420 mg mefloquine, 1200 mg sulfadoxine and 60 mgpyrimethamine; and a combination of1500 mgsulfadoxineand 75 mgpyrimethamine. After treatment, follow-up examination wasperformed dailyfor! week and then weeklyfor another3 weeks. The cure rate in the mefloquine groups (within the study period of 28 days) was 100%, and in the thirdgroup 75%o. Normal blood levels ofthe administered drugs werefound in 6patients of the third group who were not cured; they were subsequently cured with a single dose of 1000 mg ofmefloquine. Drug tolerance was good and no toxic effects were demonstrated in blood and urine examinations. While the doses in the drug combinations (containing mefloquine) gave very good results, we would recommend a slightly higher dose combination of mefloquine with sulfadoxine-pyrimethamine for the treatment of fakciparum malaria in areas with a high prevalence of chloroquine resistance.

Owing to a variety of factors, malaria is at present a one of these patients was resistant to this drug in resurgent disease. The number of cases per year has experimentally induced malaria in humans (4). been estimated at over 300 million, and in Africa Several years later this resistance was also found in alone it is thought to be the cause of death of more cases from the country's Pacific coast (5), and has than 1 million people every year. One of the many recently been confirmed both in vitro and in vivo in a problems involved with malaria is the widespread larger number of cases from different parts of resistance of Plasmodium falciparum to antimalarial Colombia (6,7). In 1973 a review of the geographical drugs (1). Although the chemotherapy of malaria is distribution of resistance to 4-aminoquinolines cited the subject of many papers and other publications, other countries in Central and South America as well practising physicians in the tropics may find them as parts of south-east Asia (8). hard to obtain. Those with this difficulty should try Resistance of P.falciparum to combined pyri- to consult the recent WHO monograph on thesubject methamine-sulfadoxine was initially seen in just a (2). few cases in a study of experimentally induced Chloroquine resistance in P.falciparum malaria malaria in Brazil (9). Recent publications from that was well documented for the first time in 1961 in two country have shown that, in cases from the Amazon patients from the Magdalena valley in the north- region, resistance to pyrimethamine-sulfadoxine was eastern part ofColombia (3). The strain isolated from as high as 630/ (10, 11). Similar findings were also reported from south-east Asia (12) and many other ' Professor of Parasitology, Faculty of Medicine, University of countries, including Colombia (13). Resistance to Antioquia, P.O. Box 1226, Medellin, Colombia. Requests for reprints should be sent to this author. chloroquine and pyrimethamine-sulfadoxine has also 2 State Health Central Laboratory and Corporation for been described in Africa (14) and in Papua New Biological Investigations, Medellin, Colombia. Guinea (15). 4577 -731 732 D. BOTERO ET AL.

The widespread and increasing resistance of for 1 week; only one patient dropped out. P.falciparum to these drugs has necessitated the Age, weight, height, past history of allergic reac- development of new antimalarials and more effective tions and concomitant associated illnesses, if present, drug combinations. As a result, mefloquine or were recorded for each patient at the initial quinolinemethanol hydrochloride, which is related to examination. All patients gave their verbal consent to quinine, was developed by the US Army Antimalarial be included in the study. The following clinical Drug Program after screening more than 250 000 parameters were assessed before treatment and on possible drugs (16). With a mean half-life in the each visit: body temperature, blood pressure, pulse bloodstream of 21 days, mefloquine is active against rate, spleen palpation, liver palpation, and signs and multidrug-resistant strains of P.falciparum in single symptoms that could be attributed to malaria, such as oral doses. Since the initial phase I tolerance headache, vomiting and diarrhoea. The state of experiments reported in 1975, clinical studies have consciousness, presence or absence of chills, and shown that this drug is well tolerated when taken complications as well as any adverse reactions orally, has a high radical cure rate in P.falciparum occurring during the study were recorded, indicating infections, and displays dramatic suppressive the type, severity, date of onset and duration of the (prophylactic) activity against this species and also reaction. Any concomitant medication with other against P. vivax (17). drugs was also recorded. The combination of mefloquine with pyri- The following laboratory parameters were assessed methamine-sulfadoxine shows an additive blood before and after treatment: Hb level, RBC count, schizontocidal action and the development of ESR, erythrocyte volume fraction, leukocyte count resistance was greatly delayed when tested in and differential count, platelet count, urine Plasmodium berghei (18). These findings support the examination, and serum determinations of bilirubin, interest in clinical trials using these drugs for the creatinine, alkaline phosphatase, aspartate amino- treatment ofP.falciparum malaria. The tablet used in transferase (SGOT) and alanine aminotransferase our study contained 140 mg mefloquine (base), 400 (SGPT). mg sulfadoxine and 20 mg pyrimethamine. This is The trial was conducted as a prospective different from the formulation currently being randomized double-blind study in 3 parallel groups of developed by Hoffmann-La Roche in collaboration patients, each receiving a single dose of 6 identical- with WHO, which contains 250 mg mefloquine looking tablets, which were swallowed with a glass of (base), 500 mg sulfadoxine and 25 mg water in the presence of the investigator. The pyrimethamine. The latter formulation was agreed antimalarials being investigated were: sulfadoxine upon following discussions between the company and (S), pyrimethamine (P) amd mefloquine (M), which WHO because it was considered that, with the lower- were administered according to the following scheme: dose combination, a fully curative effect might not be obtained. Group 1 (25 cases): 2 tablets (corresponding to 280 mg M + 800 mg S + 40 mg P) and 4 placebo tablets. Group 2 (26 cases): 3 tablets (corresponding to 420 mg MATERIALS AND METHODS M + 1200 mg S + 60 mg P) and 3 placebo tablets. Group 3 (24 cases): 3 tablets (corresponding to 1500 mg S + 75 mg P) and 3 placebo tablets. This study was carried out from April 1982 to February 1983 on 75 patients who had been infected The parasitological studies consisted of counts of with P.falciparum malaria in regions where the trophozoites and gametocytes of P.falciparum chloroquine-resistant strains were prevalent. These before starting treatment, followed by daily counts patients were treated and followed up for 1 month in after treatment for 7 days and then once a week for a the city of Medellin where natural transmission of maximum of 4 weeks. The presence of mixed malaria does not occur. The criteria for the selection infections with P. vivax was recorded. Blood samples of patients were: males over 14 years of age, were collected before and 24 hours after treatment for P.falciparum parasitaemia of more than 400 determination of plasma concentrations of the 3 trophozoites per mm3 with symptomatic disease, and tested drugs. no previous treatment with other antimalarials during Treatment with 1000 mg of mefloquine was the 4 weeks prior to entering the trial. All patients had reserved for those patients who were not cured with a negative Dill-Glazko test for chloroquine in the the above treatments and in whom P.falciparum urine. The patients were seen daily during the first trophozoites persisted in the blood and symptoms week following treatment and then weekly for 3 were present. The drug was given as a single dose and weeks, except for 7 cases who were followed up for a these subjects were then followed up for the standard period of 1-3 weeks, 3 cases for 2 weeks, and 2 cases period of one month. TREATMENT OF FALCIPARUM MALARIA 733

RESULTS Concomitant P. vivax infection was observed in 2 patients during the 1 month follow-up period and in 6 others after this period. These 8 patients remained in a Parasitological response non-malarious area and did not show P. vivax in the The initial parasite counts ranged from 425 to pre-treatment blood examination, which means that 280 000 (mean ± SD = 33 300 59 177) in group 1, this form of malaria was due to relapses. All were from 1849 to 300 000 (mean + SD = 28 433 ± cured with chloroquine and primaquine. 66 496) in group 2, and from 718 to 48 300 (mean ± SD = 10 916 ± 13 064) in group 3. Considering the Clinicalfindings 75 patients together (one later dropped out), we found No impairment of consciousness was found in any that most cases presented low to moderate levels of patient and the blood pressure showed no significant parasitaemia. Trophozoite counts were below changes at any time. The fever was cleared in 58% of 10 000/mm3 in 42 cases, between 10 000 and the parasitologically cured cases in group 1 within 4 100 000/mm3 in 30 cases, and above 100 000/mm3 in days of treatment, in 641o in group 2, and in 69% in 3 cases. group 3. By day 7 all the patients were afebrile. Chills Clearance of the asexual blood forms of were not observed after day 4 in any of the cured P.falciparum was obtained within 5 days in groups 1 patients. Headache and vomiting were common and 2 (no cases of parasitaemia after day 5 in group 1, symptoms before treatment and did not occur after after day 4 in group 2), and no cases of recrudescence the third day of treatment. Diarrhoea occurred less occurred in any patients from these two groups. The frequently and persisted for a few days after therapy. mean parasite clearance time (± SD) was 3.0 ± 1.6 Hepatomegaly (1-6 cm below the costal margin) was days in group 1 and 2.8 ± 1.3 days in group 2. Six of present before treatment in 17 patients from group 1, the 24 patients in group 3 (sulfadoxine-pyrimetha- 15 from group 2, and 16 from group 3. At the end of mine group) had to be treated with mefloquine (1000 the follow-up period (days 25-32), liver enlargement mg) in the period between days 3 and 8 because of an was recorded only three times in groups 1 and 2 and unsatisfactory parasitological response; in the twice in group 3. Splenomegaly, following the remaining 18 patients, clearance of asexual Hackett classification, was found before treatment to parasitaemia was achieved within 4 days. No be between classes 1 and 4 in 24 cases from group 1, 24 recrudescences were observed, which means that the from group 2, and 22 from group 3; classes 1 and 2 cure rate in the 50 cases treated with the two were the most common finding. At the end of the combinations of mefloquine and pyrimethamine- follow-up period, slight splenomegaly (in most cases sulfadoxine was 100% (within the study period of 28 class 1, i.e., palpable on deep inspiration) was found days), while the cure rate in the 24 patients treated in 20 patients from group 1, 20 from group 2, and 11 with the standard dosage of pyrimethamine-sulfa- from group 3. doxine was only 75%o. This difference between group Renal insufficiency was observed in only 2 patients 1 and 2 on the one hand and group 3 is statistically who showed a high parasitaemia of around 300 000 significant (Fisher's exact test, 2-tailed, P< 0.005). per mm3 before treatment, and their symptoms The gametocyte counts showed that 16 out of 23 subsided on day 2 after treatment. Concomitant patients in group 1, 11 out of 23 cases in group 2, and bacterial infections were seen in 2 patients with 15 out of 16 cases in group 3 had a positive gametocyte pharyngitis and bronchopneumonia which were count on days 12-16. On days 25-32, only 4 out of 20 cured with penicillin. cases in group 1 and 3 out of 20 cases in group 2 still had a low gametocyte count. However, 8 out of 12 Side-effects. Vomiting was the only symptom that patients in group 3 still had a positive and in some could be regarded as a side-effect of treatment. This cases rather high gametocyte count. was present with slight intensity in only three patients: The plasma concentrations of pyrimethamine and two from group 1 and one from group 3. sulfadoxine, which were measured by means of a Laboratory investigations specific and sensitive microbiological assay (19) before and 24 hours after the ingestion of these drugs, The non-parasitological laboratory determinations showed that in 6 patients who were not cured with this gave results in many cases that were outside the treatment the levels were within the expected range, normal range because of the malaria; no changes were compared with those in volunteers. These findings observed that could have been due to the treatment. confirm that the 6 patients had ingested and absorbed The main findings observed were low values for Hb, the drugs and that they were genuinely resistant to this erythrocyte volume fraction, RBC counts and platelet drug combination. This resistance was classified as RI counts both before and after treatment. Raised values in 1 case and RII in 5 cases. were seen before and after treatment for the ESR; 40 734 D. BOTERO ET AL. out of 73 cases showed raised total bilirubin values (25). The side-effects attributable to mefloquine in before treatment while only 5 patients still showed an our study were infrequent since vomiting occurred in increased bilirubin on days 2-4 after treatment. only 2 out of the 50 cases (in groups 1 and 2) who had Raised values for alkaline phosphatase, SGPT, received combinations of the 3 drugs. This good SGOT and creatinine were observed in several cases tolerance may be due to the smaller amounts of but the differences before and after treatment were mefloquine used in our study. not significant. The main finding in urinalysis was a It is recognized that mefloquine in the therapeutic high frequency of proteinuria, which is to be expected dose for P.falciparum is also effective against the in symptomatic malaria. blood forms of P. vivax (20) and P. malariae (26). This wide spectrum of efficacy against the three main human malaria parasites is another factor in favour of this drug. At present, however, mefloquine may DISCUSSION not be required in regions where P.falciparum is still highly sensitive to chloroquine, as in Zambia (27). A recent report on mefloquine discussed the safety, The prophylactic activity of mefloquine in drug- tolerance and efficacy of this drug (20). Advice was resistant malaria has been studied in non-immune given on how the development of resistance might be volunteers, in whom patent parasitaemia was prevented by following various procedures, including prevented when they were exposed to infected combination of mefloquine with pyrimethamine- mosquitos two weeks after receiving a single dose of sulfadoxine. The effective dose for mefloquine, when 1 g of mefloquine (28). Similar studies revealed an used alone, seems to be 1000 mg, administered as a absence of parasitaemia during 60 days' follow-up of single dose (21). This dose was found to be effective volunteers infected with a strain of P.falciparum by us in the 6 cases that did not respond to resistant to chloroquine and pyrimethamine, after pyrimethamine-sulfadoxine. We also found that the receiving different doses of mefloquine, with a combination of the three drugs was not effective maximum of 1000 mg every 4 weeks (29). against the tissue forms of P. vivax, a fact found also A large comparative field trial carried out in for mefloquine alone at the standard dose (21). Thailand, where different weekly doses of In our study, all 74 cases initially showed only mefloquine and sulfadoxine-pyrimethamine were P.falciparum, but after this infection was cured, 8 administered for 26 weeks to nearly 1000 persons, cases with P. vivax appeared. Similar findings, with showed that mefloquine was more effective in an even higher P. vivax relapse rate, were found in suppressing both falciparum and vivax Brazil (22) where 21 out of 99 cases were positive for parasitaemias. Both groups tolerated the drugs well P. vivax after P.falciparum was cured. These findings and no toxic effects were recorded except for suggest a dominance of P.falciparum over P. vivax leukopenia in the second group. The recommended when both parasites are concomitantly infecting the weekly dose for a 50 kg individual was 180 mg of same patient. mefloquine, which is equivalent to 250 mg for a 70 kg A study in Brazil (22) recorded a 100%7o cure rate for person (30). The prophylactic use of mefloquine in P.falciparum with 1000 mg of mefloquine, but only children also gave excellent results with good 73% with the standard dose of pyrimethamine- tolerance (31). Nevertheless, this drug should be used sulfadoxine. In our study the cure rate with the latter only in high-risk groups in special circumstances. The was 7507, and with the combination of 3 drugs it was possibility of a combination with primaquine as a 100% (within the study period of 28 days); our gametocytocide and for the radical cure of vivax combination contained only 280 mg of mefloquine in infections should be explored (20). group 1 and 420 mg in group 2. A cure rate of only The recommendation not to use mefloquine freely 19.4% with pyrimethamine-sulfadoxine was and to combine it with other antimalarials is mostly obtained in a study in Thailand, where mefloquine based on laboratory experiments which showed that produced much better results (23). In the same resistance appeared when repeated weekly passages.of country, a comparative study of mefloquine (single Plasmodium berghei in mice were maintained under doses of 1500 mg) versus pyrimethamine-sulfadoxine increasing drug pressure (32). Using the P. berghei (standard doses) showed a higher cure rate with the system in rodents, several mefloquine-resistant lines former; also gastrointestinal side-effects (nausea, have been selected. All these lines lost their resistance vomiting, diarrhoea) were more common with quickly when passaged without drug pressure, and mefloquine (24). In P.falciparum cases in Burma fortunately no definitely mefloquine-resistant strains treated with mefloquine (in doses of 20 and 30 mg/kg of P.falciparum have so far been obtained from of body weight for children and 750-1000 mg for cultures in vitro (33). Experimental resistance to an adults) side-effects like nausea, giddiness and antimalarial depends mainly on the size of the vomiting were noted in about 60% of the patients parasite population exposed to the drug pressure, but TREATMENT OF FALCIPARUM MALARIA 735 it seems the para-aminobenzoic acid content in the using such a low dose of mefloquine in our country diet may influence this sensitivity by accelerating the where there is already resistance to sulfadoxine- development of resistance when the content of this pyrimethamine. In order to avoid treatment failures acid is high (34). The relation of these experiments to that would favour the development of mefloquine drug resistance in human malaria has not yet been resistance and the further spread of resistance to clarified. sulfadoxine-pyrimethamine, the dose of the Several clinical trials with combined mefloquine combination should be high enough to ensure a fully and sulfadoxine-pyrimethamine treatment for curative effect in practically all cases. For this reason, P.falciparum infections have been performed during a high-dose combination tablet containing 250 mg the last few years. In one study in Brazil, using 750 mg mefloquine, 500 mg sulfadoxine and 25 mg ofmefloquine combined with the standard dose ofthe pyrimethamine has been developed (see above). other two drugs, there was a 100% cure rate; there Studies with this combination have already been was good drug tolerance and rapid disappearance of performed; the results show that 2 to 3 ofthese higher- the clinical symptoms (35). These results are similar dose tablets are necessary to achieve a cure rate of to ours- 100% cure rate (S response) within the 100% in malaria regions where chloroquine- study period of 28 days, although our drug resistance is highly prevalent and where there is also combination included smaller amounts of some resistance to sulfadoxine-pyrimethamine (36). mefloquine. However we would not recommend

ACKNOWLEDGEMENTS

We are grateful to Dr R. H. Leimer and Dr A. Duarte of F. Hoffmann-La Roche, Basle, Switzerland, for their efficient contribution to the planning, developing and writing up of this study, and to the Malaria Eradication Programme, Medellin, Colombia, and the State Health Central Laboratory of the same city for their valuable cooperation.

RtSUMIt

ESSAI PROSPECTIF EN DOUBLE AVEUGLE DE DEUX DOSES DIFFtRENTES DE MtFLOQUINE PLUS PYRIMSTHAMINE-SULFADOXINE, PAR COMPARAISON AVEC LA SEULE PYRIMtTHAMINE-SULFADOXINE, DANS LE TRAITEMENT DU PALUDISME A FALCIPARUM

La Colombie est un pays oui le paludisme pose un therapeutique a dure 4 semaines, des examens cliniques et probleme considerable, en partie du fait de l'augmentation parasitologiques etant pratiques tous les jours au cours de la de la pharmacoresistance de Plasmodiumfalciparum. Cette premiere semaine, et une fois par semaine ensuite. On a etude avait pour objectif de tester 1'efficacite de deux doses procede a des analyses de sang et d'urine avant et apres le differentes de l'association mefloquine (M) plus sulfadoxine traitement, en recueillant du plasma a cette occasion, afin (S) et pyrim6thamine (P), par comparaison avec la dose d'evaluer les- concentrations medicamenteuses dans le classique de S et de P seules, pour le traitement du paludisme sang. a falciparum. On a traite en double aveugle, a I'aide de doses Le nombre de trophoites 6tait inferieur a 10 000 par mm3 uniques, trois groupes randomises de 25, 26 et 24 hommes dans 42 cas, compris entre 10 000 et 100 000 par mm3 dans adultes malades, presentant une parasitemie de plus de 400 30 cas et superieur a 100 000 par mm3 dans 3 cas. On a trophozoites de P. falciparum par mm3, de la facon obtenu une disparition de la parasitemie (formes asexuees) suivante: en 5 jours pour les groupes 1 et 2, sans recrudescence. Sur les Groupe 1 (25 cas): 2 comprimes (correspondant a 24 malades suivis dans le groupe 3, 6 n'ont pas 6te gueris. La 280 mg M + 800 mg S + 40 mg P) et 4 difference entre l'ensemble des groupes 1 et 2 (taux de comprimes de placebo guerison de 100%) et le groupe 3 (taux de gu6rison de 75%) Groupe 2 (26 cas): 3 comprimes (correspondant a est statistiquement significative. Chez les 6 malades non 420 mg M+ 1200 mg S + 60 mg P) et gu6ris, on a observe des concentrations normales de 3 comprimes de placebo sulfadoxine et de pyrimethamine apres le traitement, ce qui Groupe 3 (24 cas): 3 comprimes (correspondant a confirme la resistance a ces medicaments. Cette resistance 1500 mg S+75 mg P) et 3 compri- etait du type RI dans un cas et du type R2 dans les 5 autres. mes de placebo. Tolls ces patients ont ensuite e traites avec succes a l'aide Tous ces malades provenaient de regions impaludees et d'une dose unique de 1000 mg de m6floquine. Au cours de ont et traites et suivis dans la ville de Medellin, oui il n?y a la periode de suivi ou juste apres on a releve la presence aucune transmission du paludisme. La surveillance post- concomittante de P. vivax, chez 8 malades chez qui cette 736 D. BOTERO ET AL.

espece n'avait pas e detectee avant le traitement. elevee, d'environ 300 000 par mm3, a rapidement cede a Les observations cliniques avant traitement correspon- l'administration du medicament. daient aux symptomes habituels du paludisme a P. falci- Les effets secondaires ont et rares, des vomissements parum, sans alteration de la conscience. L'hyperthermie, (sans gravite) s'etant produits chez seulement deux malades qui est le symptome principal, a disparu chez la plupart des du groupe I et un malade du groupe 3. Les analyses de malades gueris parasitologiquement dans les 4 jours suivant laboratoire ont donne des resultats normaux pour des le traitement. Chez deux malades presentant une paludeens et n'ont pas r6v&lE de modifications importantes insuffisance renale avant le traitement, la parasitemie qu'on puisse attribuer a ces medicaments.

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