An open, randomized, phase III clinical trial of mefloquine and of quinine plus sulfadoxine—pyrimethamine in the treatment of symptomatic falciparum malaria in Brazil

Bulletin ofthe WorldHealth Organization, 63 (3): 603-609 (1985) i World Health Organization 1985 An open, randomized, phase III clinical trial of mefloquine and of quinine plus sulfadoxine- pyrimethamine in the treatment of symptomatic falciparum malaria in Brazil J. M. DE SOUZA,' U. K. SHETH,2 R. M. G. DE OLIVEIRA,3 H. ROULET,4 & S. D. DE SOUZA5 The clinical andparasitological response ofadult malepatients to mefloquine and to a combination of quinine and sulfadoxine-pyrimethamine during the treatment of falci- parum malaria was compared. These patients were from an area in Brazil where Plasmodium falciparum is showing increasing resistance to quinine and to sulfadoxine- pyrimethamine. The drugs were administered to 100 patients (50 in each group), based on a randomized study design. The rates ofclearance ofparasitaemia andfever were similar in both groups. However, the parasitological cure rate ("S" response) was 100%o for mefloquine but only 92%o for quinine plus sulfadoxine-pyrimethamine. Tolerance was good in both groups. The main side-effects (nausea, vomiting, abdominal pain, and dizziness) were mild, transient and required no specific treatment. Nausea and vomiting were more frequent in patients who received quinine plus sulfadoxine-pyrimethamine, while abdominal pain and loose stools or mild diarrhoea were more frequent in the mefloquine group. Tinnitus and hearing difficulty were observed following the administration of quinine plus sulfadoxine- pyrimethamine, but not after mefloquine treatment. Laboratory tests of various haema- tological and biochemical parameters were not adversely affected in either group after drug administration. It can be concluded that mefloquine, given in a single oral dose of 1000 mg, is highly effective, well tolerated, and safefor the treatment offalciparum malaria in adult males in Brazil. Mefloquine is a quinoline-methanol derivative related chemically to quinine. It was developed by the Walter Reed Army Institute of Research in Washington (1). Extensive preclinical data on the ' Adjunct Professor of Pharmacology, Health Sciences Centre, Federal University of Para, and Principal Investigator, Clinical Trial Centre, Barros Barreto Hospital, Belem, Para, Brazil. Requests for reprints should be addressed to this author at the Clinical Trial Centre. 2 Consultant, UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases, World Health Organization, Geneva, Switzerland. 3 Medical Officer, Clinical Trial Centre, Barros Barreto Hospital, Belem, Para, Brazil. 4 Technical Officer, UNDP/World Bank/WHO Special Pro- gramme for Research and Training in Tropical Diseases, Clinical Trial Centre, Barros Barreto Hospital, Belem, Para, Brazil. s Nurse Officer, Clinical Trial Centre, Barros Barreto Hospital, Belem, Pari, Brazil. pharmacology, toxicology and antimalarial activity of mefloquine have been published (2, 3):a its use- fulness in multidrug-resistant human malaria has been reported by many investigators (4-9). Resistance of Plasmodium falciparum strains to quinine (10), to the 4-aminoquinolines (1, 2, 11-16),b and to sulfadoxine-pyrimethamine combinations has been reported from Brazil and other places (17-19).C The need to develop an effective and safe drug, parti- cularly in areas where P.falciparum is resistant to the commonly available drugs, is self-evident. a Mefloquine hydrochloride (WR 142, 490 Hcl): clinical brochure. Washington, DC, Walter Reed Army Institute of Research, 1978 (unpublished document). b Relatorio da Divisao de Malaria da Sucam, Brasilia, 1981 (unpublished document). ' DE SOUZA, J. M. I Simposio de Medicina Tropical de Rondonia, 1981 (unpublished). 4559 -603- J.M. DE SOUZA ET AL. Mefloquine has been used in doses varying from 400 mg to 1500 mg of the base for the treatment of falciparum infections in adults (20-22). It has been registered under the trade name of Lariam. P.falciparum infections have shown increasing resistance to 4-aminoquinolines, to quinine, and to sulfadoxine-pyrimethamine in the Paragominas area of Brazil. The usual treatment for such resistant cases includes the combination of quinine with tetracycline, or of quinine with sulfadoxine and pyrimethamine. We have previously carried out phase I and II studies with mefloquine in P.falciparum infection, comparing it with sulfadoxine-pyrimethamine (Fansidar) in adult male Brazilian subjects (25, 26). The results of these studies showed mefloquine to be safe and effective for the treatment of chloroquine- resistant P.falciparum and led to the present study, which compared the tolerance and clinical and parasitological response to mefloquine and to a combination of quinine and Fansidar in adult males with symptomatic malaria. These patients were from an area in Brazil where P.falciparum is showing increasing resistance to quinine (10) and sulfadoxine- pyrimethamine (17-19).' PATIENTS, MATERIALS AND METHODS All the patients in the study, who were males between the ages of 18 and 55- years, originated from the endemic areas of Paragominas and suffered from symptomatic falciparum malaria. Informed consent for inclusion in the trial was obtained from all patients, after which they were admitted to the Clinical Trial Centre of the Barros Barreto Hospital, Belem. A total of 100 patients were included in the study, all (but two) of them remaining in the hospital throughout the study period of 42 days. Belem is an area where malaria transmission does not occur. Mefloquine was administered in tablets of 250 mg base, quinine as tablets of 300 mg base, and sulfa- doxine-pyrimethamine as Fansidar (each tablet con- taining 500 mg sulfadoxine and 25 mg pyrimetha- mine). The patients received their treatment, based on an open, randomized study design, as follows: (a) melfoquine, 1000 mg base as a single oral dose on day 0; or (b) quinine, 600 mg base orally, followed 4 hours later by three tablets of Fansidar on day 0 and a further 600 mg of quinine given at 8-hourly intervals for the next 2 days. Relapses of P. vivax malaria were treated with 1500 mg of chloroquine base plus 210 mg of prima- quine base. All recrudescences or treatment failures were given 1000 mg of mefloquine base (four tablets) as a single oral dose. The patients also received other drugs, such as analgesics, as required. Each patient provided a detailed medical history and was given a full clinical examination according to a standard protocol. Clinical measurements, and bio- chemical and haematological laboratory investiga- tions were also carried out. These included chest X- ray and ECG studies. Patients were examined prior to administration of the trial drug on day 0. Subse- quently, clinical examinations were carried out daily from day 0 to 7, and weekly from day 7 until day 42. Haematological studies were repeated on days 2, 4, 7, 10, 14, 28 and 42. Biochemical studies were repeated on days 1, 4, 7, 14, 28 and 42. ECG studies were repeated on days 1, 4, 7, 28 and 42. Urine analysis was performed daily for the first week, and then on days 14, 28 and 42. Blood smears were prepared and examined for malaria parasites (asexual forms and gametocytes) daily from day 0 to 42. In vitro drug sus- ceptibility tests (23, 24) for P.falciparum were carried out on day 0 and repeated as necessary. Plasma samples were collected for estimation of drug levels on day 7 and additionally in cases of recrudescence, vomiting or serious adverse reactions. Urine was tested for the presence of sulfonamides and 4-amino- quinolines by a modified Bratton-Marshall method and Dill-Glazko test, respectively, on day 0. Measure- ments of body weight and height were carried out on day 0. Body temperature was recorded twice daily (morning and evening). Stool samples were examined for blood and helminths. Clinical features such as symptoms, pulse rate, and respiration were recorded daily. Blood pressure was recorded daily from day 0 to 7, and subsequently on days 10, 14, 28, 35 and 42. RESULTS A total of 100 patients entered the trial, of whom 50 received mefloquine and 50 quinine plus sulfadoxine- pyrimethamine. One patient in the mefloquine group vomited after drug administration and was not included in the series, thus leaving 49 patients in the mefloquine group. Two patients from the quinine and sulfadoxine-pyrimethamine group left the hospital after two weeks, but continued to attend the out- patient department weekly for assessment. The mean body weight of patients on day 0 in the mefloquine group was 55.7 kg, and in the quinine plus sulfadoxine-pyrimethamine group was 55.0 kg. Thus the body weights in both groups were com- parable. 604 PHASE III CLINICAL TRIAL OF MEFLOQUINE Clinical findings Blood pressure and pulse rate showed no signi- ficant change. All ECGs remained normal. There were no significant changes in either respiratory or neuropsychiatric systems. In the mefloquine group, a known epileptic patient had an epileptic seizure on day I which was well controlled with the appropriate drugs; thereafter he remained free of attacks. Splenomegaly was noted on day 0 in 40 patients who received mefloquine and 41 patients who received quinine plus sulfadoxine-pyrimethamine. There was a significant reduction in the number of enlarged spleens and individual sizes during the 42- day study period. At the end of the study, one subject from the mefloquine group and two from the quinine plus sulfadoxine-pyrimethamine group still had enlarged spleens. There was no significant difference between both groups. Hepatomegaly was present in 47 subjects in the mefloquine group on day 0 (2.1 cm below the costal margin), but only one had an enlarged liver on day 42. In the quinine plus sulfa- doxine-pyrimethamine group, 48 subjects had hepatomegaly on day 0 (2.3 cm below the costal margin); this persisted in 6 subjects until day 42 (0.2 cm below the costal margin). Laboratory investigations In both groups, the initial mean haemoglobin, red blood cell counts, and erythrocyte volume fraction were below normal in 30-33Oo of subjects. This was probably the result of repeated attacks of malaria and of multiple helminth infections which were present in these subjects. In all cases, the values tended to become normal towards the end of the study period. In the mefloquine group, the mean haemoglobin value on day 0 was 6.9 mmol/l (range, 3.1-9.5) and 8.3 mmol/l (range, 4.7-10.0) on day 42. The mean red blood cell count on day 0 was 3.8 x 1012/1 (range, 1.4-5.0) and 4.5 x 1012/1 (range, 2.6-5.4) on day 42. The mean erythrocyte volume fraction was 0.33 (range, 0.12-0.46) on day 0 and 0.39 (range, 0.23-0.49) on day 42. In the quinine plus sulfadoxine-pyrimethamine group, the mean haemoglobin value on day 0 was 7.3 mmol/l (range, 4.7-10.1) and 8.5 mmol/l (range, 7.4-9.9) on day 42. The mean red blood cell count on day 0 was 4.0 x 1012/1 (range, 2.5-5.4) and on day 42 it was 4.6 x 1012/1 (range, 3.9-5.3). The mean erythro- cyte volume fraction on day 0 was 0.35 (range, 0.22-0.49) and on day 42 it was 0.41 (range, 0.35-0.47). There was no significant difference between either group in the initial white blood cell values and those at the end of the study period. In all cases, these values were within the normal range shown by the target population. Both groups exhibited eosinophil counts ranging from 0% to 50%, but this was probably related to the presence of helminth infections, as indicated by ova in the stools of all the patients. No significant change was seen in total or differential white blood cell counts after mefloquine or quinine plus sulfadoxine-pyrimethamine administration. Serum bilirubin, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and serum creatinine levels were within normal limits in both treatment groups before and after admini- stration of the trial drugs. In the mefloquine group, two patients had above-normal serum glutamic oxalo- acetic transaminase (SGOT) and serum glutamic pyruvic transaminase (SGPT) values on day 0 and two other patients (one each on day 4 and day 7) also had elevated values. In the quinine plus sulfadoxine- pyrimethamine group, 3 patients had above-normal values of SGOT and SGPT on day 0; these values became Rnormal in all cases by day 14. Altogeiher, 98% of the patients in both groups had helminth infections on day 0. In both groups, a number of cases had traces of albumin and urobili- nogen in the urine during the first 3-4 days of the study. Some cases also had an occasional increased number of leukocytes and red blood cells in the urine, but the levels reverted to normal without treatment. These changes were not significant in either treatment group. Parasitological response Table 1 shows details of the number of patients with positive parasite counts and fever on day 0 and the subsequent rates of clearance following drug administration. Table 2 shows the comparative response of P.falciparum parasitaemia and the incidence of P. vivax infection in both groups. Mefloquine group. All 49 patients who received mefloquine had asexual forms of P.falciparum in their blood on day 0. This parasitaemia persisted in all cases on day 1 after drug administration, but every patient became negative by day 6 (Table 1). Gameto- cytes of P.falciparum were present in 21 cases on day 0, 32 cases on day 7, and 4 cases on day 28, after which all subjects were negative until day 42. P. vivax infec- tion was observed in two cases (one each on days 29 and 37). Quinine plus sulfadoxine-pyrimethamine group. All 50 patients who received quinine plus sulfado- xine-pyrimethamine had asexual parasitaemia due to P.falciparum on day 0 (Table 1). This parasitaemia persisted in all cases on day I after drug admini- stration and in 36 cases on day 2; all patients were negative by day 7. Recrudescences were observed in 4 cases between days 16 and 21. Gametocytes of 605 J.M. DE SOUZA ET AL. Table 1. Effect of mefloquine and quinine plus sulfadoxine-pyrimethamine on fever and asexual parasitaemia in patients with falciparum malaria Mefloquine group (49 patients) Quinine plus sulfadoxine-pyrimethamine group (50 patients) Fever Mean parasitaemia Fever Mean parasitaemia Day of No. No. Count No. No. Count' treatment positive positive (per mm3) positive positive (per mm3) 0 47" (96)' 49 (100)' 19 490 47" (94)' 50 (100)' 19 628 1 30 (62) 49 (100) 14 186 30 (60) 50 (100) 10 864 2 10 (21) 40 (82) 382 9 (18) 36 (72) 666 3 2 (4) 19 (39) 29 1 (2) 19 (38) 9 4 1 (2) 7 (14) 6 0 (0) 7 (14) 5 5 1 (2) 1 (2) 10 1 (2) 2 (4) 20 6 0 (0) 0 (0) 0 0 (0) 2 (4) 20 7 1 (2) 0 (0) 0 1 (2) 0 (0) 0 Four patients had recrudescence between days 16 and 21. h Mean temperature 38.7 ±0.9 0C. Figures in parentheses are percentages. d Mean temperature 38.3 ± 0.9 °C. P.falciparum were present in 26 cases on day 0, 39 cases on day 7, 15 cases on day 28, and 3 cases on day 35, after which all subjects were negative until the end of the study period. P. vivax infection was observed in 7 cases between days 16 and 38 (Table 2). Table 2 compares the parasitological responses to mefloquine and quinine plus sulfadoxine-pyrimetha- mine. Parasites were cleared from the circulation in all patients within six days in the mefloquine group, and within seven days in the quinine plus sulfadoxine- pyrimethamine group. None of the patients showed recrudescence after mefloquine. However, recrud- escences were observed in 4 patients following quinine plus sulfadoxine-pyrimethamine treatment, giving an overall cure rate of 920%o in this group. Fever and other side-effects Of the patients who received mefloquine, 47 had fever on day 0 (Table 1); this cleared in 96% of the cases by day 3. After day 5, no patients were febrile, although a slight rise in temperature (37.5 °C) was observed in one case on day 7. Table 2. Comparative efficacy of mefloquine and quinine plus sulfadoxine-pyrimethamine for treatment of falciparum malaria Treatment response (P. falciparum ) No. of Mean highest count P. vivax Treatment patients of asexual forms of S RI RI) Ril) Cure rate relapses P. falciparum on day 0 (%) Mefloquine 49 19 580/4A 49 0 0 0 100 2 cases (one each on days 29 and 37) Quinine plus 50 19 626/pl 46 4 0 0 92 7 cases (one sulfadoxine- each on pyrimethamine days 16, 21, 25, 31, 34, 35 and 38) 606 PHASE III CLINICAL TRIAL OF MEFLOQUINE Table 3. Comparative incidence of side-effects observed in patients given mefloquine base or quinine plus sulfadoxine -pyrimethamine Percentage incidence of symptoms after: Symptoms Mefloquine (49 patients)" Quinine plus sulfadoxine-pyrimethamine (50 patients)" Nausea 12 48 Vomiting 16 28 Dizziness 16 20 Diarrhoea 24 16 Abdominal pain 16 4 Bradycardia - 2 Itching 4 Tinnitus - 34 Hearing difficulty 8 a During the first four days following drug administration. In the quinine plus sulfadoxine-pyrimethamine group, 47 patients had fever on day 0. This cleared in 98% of the cases on day 3. One patient had a slightly raised body temperature on day 5 and another on day 7. The rest of the patients in this group were free from fever from day 4 onwards. The main subjective side-effects observed within four days of drug administration, i.e., those which may be attributed to the trial drug, were nausea, vomiting, mild diarrhoea, dizziness, and abdominal pain. These results are summarized in Table 3. Nausea (48%) and vomiting (28%) were more frequent in patients who received quinine plus sulfa- doxine-pyrimethamine. In contrast, abdominal pain and loose stools or mild diarrhoea (more than 3-4 stools/day) were more frequent in the mefloquine group. Tinnitus and hearing difficulty were not observed in any patient receiving mefloquine, whereas in the quinine plus sulfadoxine-pyrimetha- mine group, 34% had tinnitus and 8% had mild to moderate reversible hearing loss. No patient in either group needed any specific treatment for these side- effects. DISCUSSION The object of the present trial was to compare the safety, efficacy, and side-effects of mefloquine base (1000 mg, given orally in one single dose) with standard, regimens of quinine plus sulfadoxine- pyrimethamine, given over a period of 3 days, for the treatment of falciparum malaria. The study was conducted in adult male patients from an area of Brazil where increased resistance of P.falciparum to quinine and to sulfadoxine-pyrimethamine (Fansidar) had been reported. The study examined the clearance of fever and parasitaemia, side-effects, and measurements of biochemical and haemato- logical parameters following drug administration. The parasitological cure rate ("S" response) was 100%o for mefloquine and 92% for quinine plus sulfadoxine-pyrimethamine. There were four RI responses in the latter group; RII or RIII responses were not observed in either group. Neither meflo- quine nor quinine plus sulfadoxine-pyrimethamine appeared to have any effects on gametocytes. The rate of clearance of fever was not significantly different in the two groups. Fever was cleared by day 3 in 9607o of the cases in the mefloquine group and 980o of the cases in the quinine plus sulfadoxine- pyrimethamine group. The most common side-effects were nausea, vomiting, abdominal pain, loose stools, and dizziness. Nausea and vomiting were more frequent in the quinine plus sulfadoxine-pyrimeth- amine group, whereas abdominal pain and mild diarrhoea were more common after mefloquine administration. The incidence of tinnitus (34%) and partial loss of hearing (8%7o), as expected, was only observed in the quinine plus sulfadoxine-pyrimeth- amine group. These side-effects were mild, transient, and did not require any specific treatment. Neither mefloquine nor quinine plus sulfadoxine- pyrimethamine produced any adverse effects on the haemopoetic system or on liver or kidney functions, as shown by various laboratory tests. No drug inter- actions were observed in either group. 607 608 J.M. DE SOUZA ET AL. Thus, mefloquine, given in a single oral dose of 1000 mg, was found to be highly effective and safe, and was well tolerated during the treatment of falci- parum malaria in adult male Brazilians. The advan- tages of this drug, which can be given as a single oral dose for the treatment of multi-resistant falciparum malaria, are therefore obvious. ACKNOWLEDGEMENTS We wish to thank the authorities of WHO/PAHO and the Brazilian Ministry of Health/SUCAM/SNEPS/DNPS and collaborators; we also thank the mefloquine project staff and the technical and administrative personnel of the Barros Barreto Hospital (HBB) for their support in carrying out the project. We are especially grateful to Dr Milvio Tavares de Oliveira Junior (Tropical Diseases Outpatient Unit, HBB) and to Dr Virgilio Estolio do Rosario (Malaria Programme, Instituto Evandro Chagas) for their understanding of the Mefloquine Project objectives and for their continued assistance. The study received the financial support of the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases and the Brazilian Ministry of Health. RESUME ESSAI CLINIQUE DE PHASE 111, OUVERT ET RANDOMISE, DE LA MEFLOQUINE ET DE L'ASSOCIATION QUININE PLUS SULFADOXINE-PYRIMETHAMINE DANS LE TRAITEMENT DU PALUDISME SYMPTOMATIQUE A FALCIPARUM AU BRESIL On a compare les reponses cliniques et parasitologiques A la mefloquine et A I'association quinine plus sulfa- doxine-pyrimethamine au cours du traitement du paludisme A falciparum chez des hommes adultes. Ces malades prove- naient d'une region du Bresil ou Plasmodium falciparum montre une resistance croissante A la quinine et A la sulfa- doxine-pyrimethamine. Ces medicaments ont e adminis- tres A 100 malades (50 de chaque groupe), selon un plan d'etude randomise. La parasitemie et la fievre ont regresse dans des proportions semblables dans les deux groupes. Cependant, le taux de guerison parasitaire, (reponse "S") etait de 100%7o pour la mefloquine, mais seulement de 92% pour la quinine plus sulfadoxine-pyrimethamine. Les medicaments ont et bien toleres dans les deux groupes. Les principaux effets secondaires (nausees, vomissements, douleurs abdominales et vertiges) etaient peu intenses et passagers et n'ont pas necessite de traitement specifique. Les nausees et les vomis- sements etaient plus frequents chez les malades recevant de la quinine plus sulfadoxine-pyrimethamine, alors que les douleurs abdominales et des selles molles ou une diarrh6e legere se sont montrees plus frequentes chez le groupe sous mefloquine. Des acouphenes et des troubles auditifs ont et observes uniquement avec l'association quinine plus sulfa- doxine-pyrimethamine. Dans les deux groupes, les para- metres hematologiques et biochimiques n'ont pas et affec- tes par I'administration du medicament. En conclusion, on peut affirmer qu'au Bresil l'adminis- tration buccale d'une dose unique de 1000 mg de meflo- quine est tres efficace, bien toleree et sans danger pour le traitement du paludisme a falciparum chez les hommes adultes. REFERENCES 1. CANFIELD, C. J. & HEIFFER, M. H. 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