A phase II clinical trial of mefloquine in Brazilian male subjects

Bulletin ofthe World Health Organization, 61(5): 815-820(1983) World Health Organizat ion 1983 A phase II clinical trial of mefloquine in Brazilian male subjects JOSE-MARIA DE SOUZA Mefloquine was compared with sulfadoxine-pyrimethamine for safety and efficacy in a randomized, double-blind clinical trial in adult males from a malaria-endemic area of Brazil. A total of 99 oligosymptomatic and symptomatic volunteers with Plasmodium falciparum parasitaemia took part in the trial; 49 were given 1000 mg ofmefloquine and the remainder received 1500 mg of sulfadoxine plus 75 mg ofpyrimethamine, in a single oral dose. Mefloquine was 100%1o successful in clearing parasitaemia within 7 days; there were no recrudescences. Sulfadoxine-pyrimethamine was less successful; 35 cases showed an S-type response, 8 an RI response, 3 an RII, and 2 an RIII response. The side-effects ofmefloquine were mild and transient and included headache, nausea, vomiting, dizziness, and diarrhoea. A satisfactory weight gain and rise in haemoglobin level were seen in both groups. Resistance of Plasmodium falciparum strains to quinine, 4-aminoquinolines, and sulfadoxine-pyri- methamine has been reported from various parts of the world, including Brazil (1-12, J. M. de Souza, un- published observations, 1981). There is thus a great need for an effective, safe alternative drug for use against multiresistant malaria. Mefloquine, a quino- line-methanol derivative chemically related to quin- ine, was developed at the Walter Reed Army Institute of Research for the treatment of such infections (11), and extensive data on its pharmacology, toxicology and antimalarial activity have already been published (12, 13).a Its usefulness in treating multidrug-resis- tant malaria has been reported by many investigators (14-19). We have previously carried out a phase I study in adult male Brazilian volunteers from an area endemic for P.falciparum infection, to compare mefloquine with sulfadoxine-pyrimethamine for tolerance and safety (20). The present report describes a phase Il/III double- blind randomized trial on 99 adult male Brazilians from an endemic area, who had P.falciparum para- sitaemia. Mefloquine was compared with a combi- nation of sulfadoxine and pyrimethamine, for its effectiveness in clearing parasitaemia, safety, and side-effects. The study was carried out at the Barros Barreto Hospital, Belem, Para, Brazil. Principal Investigator, Clinical Trial Centre, Barros Barreto Hospital, Belem, Para, Brazil. a Mefloquine hydrochloride (WR 142490 HCI); clinical bro- chure. Walter Reed Army Institute of Research, Washington, DC, 1978 (unpublished document). MATERIALS AND METHODS A randomized, double-blind trial was carried out using a "double-dummy" system of drug adminis- tration. The duration of the study was 66 days. All patients were males over 18 years of age from the malaria-endemic area of Paragominas, and all had blood smears positive for asexual forms of P.fal- ciparum. None of the subjects had received any anti- malarial drugs for 4 weeks prior to admission to the study. At the time of screening and selection, none of the subjects had a fever, but some of them developed malarial fever before drug administration. Thus the trial included both oligosymptomatic and sympto- matic patients with P.falciparum infection. Informed consent for participation in the trial was obtained. The volunteers remained in the hospital throughout the 66-day study period. One group of patients was given mefloquine, in the form of four tablets of 250 mg (base) each, plus 3 placebo tablets, as a single oral dose on day 0. A second group received 3 tablets of sulfadoxine-pyri- methamine (each tablet containing 500 mg of sulfa- doxine and 25 mg of pyrimethamine) and 4 placebo tablets. The subjects received other drugs, such as analgesics and vitamin supplements, as required during the study. Any relapse due to P. vivax was treated with chloroquine (1500 mg) and primaquine (210 mg) and recrudescence and treatment failure were treated with quinine sulfate (2 g per day for 3 days) and tetra- cycline (1 g per day for 3 days). 4344 -815- J. M. DE SOUZA Before treatment, each patient gave a detailed his- tory and received a full clinical examination accord- ing to a standard protocol, including chest X-ray and electrocardiogram (ECG). Laboratory investigations including examination of blood, haemoglobin (Hb), red blood cell (RBC) count, erythrocyte volume frac- tion (haematocrit), total and differential white blood cell (WBC) counts, platelet count, and reticulocyte count, were carried out on days - 2 to 7, 10, 14, 21, 28, 35, 42, 49, 56, and 63. Biochemical investigations, including estimations of serum glucose, blood urea, serum bilirubin, aspartate aminotransferase (SGOT), alanine aminotransferase (SGPT), alkaline phos- phatase, serum creatinine, serum cholesterol, tri- glycerides, calcium, sodium, potassium, chloride, magnesium, phosphate, iron, albumin, and proteins were done prior to drug administration and again on days 0, 1, 4, 7, 14, 21, 28, 42, and 63. Urine analysis was done daily during the first 10 days from day - 2, and again on days 14, 21, 28, 42, and 63. Stools were examined for blood and parasites on days - 2, 0, and 7. ECG studies were repeated on days - 2, 0, 1, 4, 7, 28, and 63. Blood smears were prepared and examined for malarial parasites (asexual forms and gametocytes) daily from day - 2 to day 7 and then at least once a week until day 63. If patients had fever, smears were examined more frequently. Plasma samples were collected and tested for drug level on day 7 and additionally if there was a recrud- escence, or vomiting after drug administration, or in the case of a serious adverse reaction. In vitro drug susceptibility tests of P.falciparuin were carried out on day 0 and again as necessary. Urine was examined for the presence of sulfonamides and 4-aminoquino- lines by a modified Bratton-Marshall method and the Dill-Glazko test, respectively, prior to drug adminis- tration. Clinical features such as pulse rate, body tempera- ture, respiration and clinical symptoms were recorded daily. Blood pressure was recorded daily for the first 7 days and then once a week. RESU LTS A total of 99 volunteers entered the trial, of whom 49 received mefloquine and 50 sulfadoxine-pyrimeth- amine. One patient from the latter group left the trial on day 2 and another on day 5, leaving 48 subjects. One further patient from this study left hospital on day 35; the remainder completed the study. In the mefloquine group, all 49 patients completed the study. Some of the biochemical investigations, e.g., serum iron, chloride, uric acid, and magnesium were carried out in only 12-50%1o of cases. In vitro studies of the sensitivity of P.falciparum to mefloquine and chloroquine were carried out, using the WHO standard macrotechnique, on isolates from 47 subjects. The mean body weight of the mefloquine group was 56.1 kg (range, 41.3-76.5 kg) on day 0 and 60.4 kg (range, 45.5-81.0 kg) on day 63. There was a mean weight gain of 4.3 kg during the study. The mean body weight of the sulfadoxine-pyrimethamine group was 57.2 kg (range, 43.4-63.7 kg) on day 0 and 62.0 kg (range, 46.0-81.0 kg) on day 63. The mean weight gain was 4.8 kg. Individual variations in weight gain were wide; there was no statistically sig- nificant difference in weight gain between the two groups. Clinical findings Blood pressure and pulse rate showed no signifi- cant changes in either group; all ECGs remained normal. There were no significant changes in either the respiratory or neuropsychiatric systems. Splenomegaly was seen on day 0 in 30 patients who received mefloquine and 22 patients who received sulfadoxine-pyrimethamine. There was a significant reduction in the number of enlarged spleens and in individual sizes during the 63-day study period. At the end of the study, one subject in each group still had splenomegaly. There was no significant difference between the groups. Hepatomegaly was present in 39 subjects in the mefloquine group on day 0 (2.4 cm below costal margin), and 9 subjects still had an enlarged liver on day 63 (0.3 cm). In the sulfa- doxine-pyrimethamine group, 39 subjects had hepatomegaly on day 0 (2.46 cm), and on day 63, hepatomegaly persisted in 8 subjects (0.43 cm). There was no significant difference between the groups. Laboratory investigations In both groups, the initial mean Hb, RBC count, and erythrocyte volume fraction values were below normal, possibly as a result of previous attacks of malaria, and the helminth infections that were present in each case. In all cases, these values tended to become normal towards the end of the study. In the mefloquine group, the mean haemoglobin value on day 0 was 6.8 mmol/litre (range, 3.92-9.7) and on day 63, 8.9 mmol/litre (range, 6.9-11.2). The mean RBC count on day 0 was 3.7 x 1012/litre (range, 2.1 x 1012-5 x 1012 ) and on day 63 it was 4.8 x 1012 per litre (range, 4.2 x 1012-5.4 x 1012). The mean erythro- cyte volume fraction on day 0 was 0.32 (range, 0.18- 0.44) and on day 63, it was 0.4 (range, 0.34-0.5). In the sulfadoxine-pyrimethamine group, the mean value for Hb on day 0 was 6.9 mmol/litre (range, 3.98-9.0) and 8.6 mmol/litre (range, 4.6-10.0) on day 63. The mean RBC count was 816 PHASE 11 CLINICAL TRIAL OF MEFLOQUINE 3.77 x 10'2/litre (range, 2.3 x 1012-4.0 x 1012) on day 0 and 4.62x 10'2/litre (range, 3.2x 10'2-5.0x 1012) on day 63. The mean erythrocyte volume fraction was 0.33 (range, 0.21-0.47) on day 0 and 0.41 (range, 0.25-0.48) on day 63. White blood cell counts were within the normal range. Both groups had high eosinophil counts ranging from 10% to 34%0 of the total WBC count. No significant change was seen in total or differential WBC counts after mefloquine or sulfadoxine-pyri- methamine treatment. None of the biochemical tests showed any drug- related changes in either group. Some cases had SGOT and SGPT values that were 10-1507o higher than normal before treatment; these became normal within 1-2 weeks after drug administration. One case in the sulfadoxine-pyrimethamine group had high SGOT and SGPT levels on day 0 and day 1; these gradually subsided over the next 3 weeks. This was probably a case of viral hepatitis. Serum iron in both groups was below normal on day 0, but reached normal values by the end of the study period. All the subjects in both groups showed single or multiple helminth infections with Ascaris, hook- worm, Strongyloides, or Trichuris. Associated proto- zoa seen in some cases were Entamoeba histolytica, Giardia lamblia, and Endolimax nana. In both groups, urine samples showed traces of protein and urobilinogen in the early stages of the study. This may have been due to the destruction of red blood cells that occurs in malaria. Some cases showed an increased leukocyte count, RBC count, and casts, all of which cleared without treatment. None of the changes were related to administration of mefloquine or sulfadoxine-pyrimethamine. The plasma levels of mefloquine, sulfadoxine and pyrimethamine will be reported elsewhere. Parasitological response All 49 subjects who received mefloquine had blood smears positive for asexual forms of P.falciparum on day 0, and all were clear by day 6 (Table 1). One patient who was clear on day 2 had a positive smear on day 7, but was again clear on day 8 without treatment. Altogether, 48 cases remained free of P.falciparum till day 63; one patient, who had vomited after taking the drug, had a positive smear for P.falciparum asexual forms on day 49. His blood level of mefloquine 6 hours after drug administration was 711 gg/litre, and on day 12 was 245 Ag/litre. Thus this was probably not an RI response, but a recrudes- cence due to low blood drug levels. Gametocytes of P.falciparum were present in 31 cases on day 0, 38 cases on day 7 and persisted in 8 Table 1. Rate of clearance of fever and parasitaemia in patients with falciparum malaria given mefloquine or sulfa- doxine- pyrimethamine Mefloquine group Sulfadoxine-pyrimethamine group Day Fever Parasitaemia Fever Parasitaemia No. % No. % No. % No. % 0 22 100 49 100 17' 100 48d 100 1 8 37 43 88 15 88 42 88 2 8 37 17 35 8 47 15 31 3 3 14 5 10 4 24 10 21 4 1 5 1 2 2 12 7 15 5 0 0 1 2 1 6 5 10.4 6 0 0 0 0 3 18 5 10.4 7 0 0 1 2 5 29.4 6 12.5 14 0 0 0 0 1 6 3 6.3 28 0 0 0 0 0 0 2 4 63 0 0 0 0 0 0 0 0 eMean temperature, 37.36 ±0.94 ° C. bMean count, 10 237 ± 19 682 per mm3. cMean temperature, 37.25 ± 0.76 OC. d Mean count, 7 883 ± 24 436 per mm3. 817 J. M. DE SOUZA cases till day 28. There were no gametocytes on day 63. Relapse due to P. vivax was seen in 11 cases, as shown in Table 2. The 48 cases in the sulfadoxine-pyrimethamine group who completed the study were positive for asexual forms of P.falciparum on day 0, and all were clear by day 63 (Table l).In this group, 35 cases (73 0o) showed an S-type response, 8 patients showed an RI response, 3 cases an RII response, and 2 cases an RIII response. Gametocytes of P.falciparum were present in 35 cases on day 0, 48 cases on day 7, 20 cases on day 28, and 2 cases on day 63. Relapse due to P. vivax occurred in 15 cases, as shown in Table 2. Thus, with mefloquine the cure rate was 100%, with one recrudescence that was probably due to low blood drug levels. With sulfadoxine-pyrimethamine, the cure rate was 73%, with 8 RI, 3 RII, and 2 RIII responses. The rate of clearance of parasitaemia was quicker with mefloquine (98% on day 4) than with sulfadoxine-pyrimethamine (87.50%o on day 7). Body temperature (Table 1) In the mefloquine group, 22 patients had fever on day 0 and all were cleared by day 5. In the sulfa- doxine-pyrimethamine group, 17 cases had fever on day 0, and 16 (940%o) were clear by day 5. Fever recurred in some patients on days 6 and 7 and 100%o clearance was seen between days 14 and 28. In vitro test Altogether, 47 isolates were examined for sensi- tivity to mefloquine and chloroquine, using the in Table 2. Number of blood smears positive for P. vivax in patients with falciparum malaria after treatment with mefloquine or sulfadoxine-pyrimethamine Sulfadoxine-Day Mefloquine pyrimethamine 7 0 0 14 0 2 21 0 3 28 0 6 35 0 6 42 5 3 49 3 4 56 3 3 63 0 3 Total 11 15 vitro macrotest to assess the inhibition of schizont maturation after 24 hours' incubation in the presence of different concentrations of the drugs. All patients had parasites that were resistant to chloroquine, and 9 tests showed resistance to mefloquine. The concen- tration of mefloquine required was 0.5-1 tzmol/litre in 20 cases, 1.5 ttmol/litre in 18 cases, and up to 2 itmol/litre in 9 cases. Side-effects All the subjects in the study were from an area where malaria, helminthiasis, intestinal protozoal infections, and malnutrition are common. Most of the volunteers had low haemoglobin, low serum albumin, enlarged spleen and liver, and helminth infections. When selected for study, all had blood smears that were positive for P.falciparum asexual forms, and were oligosymptomatic. However, many developed malarial fever before the drugs could be ad- ministered. Malarial fever is itself associated with headache, nausea, vomiting, dizziness, and often ab- dominal pain, making it difficult to differentiate be- tween disease symptoms and drug-induced side- effects. An attempt has been made to analyse separately the symptoms in subjects with and without fever on day 0. The side-effects occurring during the first 4 days after drug administration included headache, nausea, vomiting, mild diarrhoea, and dizziness (Table 3). All l able 3. Side-effects occurring during the first four days after administration of mefloquine or sulfadoxine-pyri- methamine, in subjects with and without malarial fever Sulfadoxine- Mefloquine pyrimethamine Side-effect With Without With Without fever fever fever fever Headache 22/22 6/27 15/17 15/31 Dizziness 22/22 9/27 16/17 9/31 Nausea 19/22 4/27 11/17 4/31 Vomiting 7/22 2/27 4/17 0/31 Diarrhoea 9/22 6/27 6/17 3/31 these symptoms were mild or moderate and transient. In some cases, symptomatic treatment was given. With mefloquine, the incidence of loose stools, vomiting, nausea, and dizziness was higher than with sulfadoxine-pyrimethamine. However, none of the side-effects with either drug was disturbing or serious. 818 PHASE II CLINICAL TRIAL OF MEFLOQUINE DISCUSSION The objective of this study was to compare the safety, efficacy, and tolerance of mefloquine (1000 mg) with that of sulfadoxine-pyrimethamine (1500 mg and 75 mg, respectively) given as a single oral dose to oligosymptomatic adult male subjects with falciparum malaria. The drugs were compared in terms of their rate of clearance of parasitaemia and clinical symptoms, the response of P.falciparum to the drug, side-effects, and changes in various haematological and biochemical factors. The cure rate for mefloquine was 100%/o, compared with 7507o for sulfadoxine-pyrimethamine. One case in the mefloquine group showed an RI-type response, but he had vomited soon after taking the drug, and had low blood drug levels 6 hours and 12 days after administration. In the sulfadoxine-pyrimethamine group, there were 8 cases with an RI response, 3 with an RII response, and 2 with an RIII response. The in vitro macrotest showed that almost all cultured parasites (from 47 cases) were sensitive to mefloquine but resistant to chloroquine. The rate of clearance of parasitaemia and fever was faster with mefloquine than with sulfadoxine-pyri- methamine. Neither drug had any effect on gameto- cytes, though more gametocytes were seen after sulfadoxine-pyrimethamine treatment than after mefloquine. The incidence of side-effects in the two groups was comparable, although there was a higher incidence of dizziness, nausea, and diarrhoea with mefloquine. However, all side-effects were mild, transient, and not disturbing and no specific treatment was needed. Neither mefloquine nor sulfadoxine-pyrimeth- amine produced any adverse effects on the haemato- poietic system or on liver or kidney functions. Mefloquine, given in a single oral dose of 1000 mg, was well tolerated, safe, and highly effective. Clini- cally, there was no significant difference in the toler- ance and safety of the drugs. However, mefloquine was more effective, producing a 100(7o S-type response, compared with a cure rate of 73%7o for sulfa- doxine-pyrimethamine. In particular, this study showed that P.falciparum strains from this endemic region of Brazil have developed resistance to sulfadoxine-pyrimethamine. In addition, the in vitro macrotest showed that isolates from 47 cases had parasites that were resistant to chloroquine. Relapses due to P. vivax occurred after mefloquine treatment, but they appeared later than those occurring after sulfadoxine-pyrimethamine. Mefloquine has the advantage of being administered in a single oral dose, and has been shown to be safe and effective in the treatment of chloroquine-resistant falciparum malaria. ACKNOWLEDGEMENTS I wish to thank the authorities of WHO/PAHO and the Brazilian Ministry of Health/SUCAM/SNPES/DNPS and collaborators; I also thank the monitors of the project, Dr Edward Brian Doberstyn, Dr Karl H. Rieckmann, and Dr U. K. Sheth. I am grateful too to the clinical officer, nurses, laboratory technicians, secretary and administrative personnel of the Barros Barreto Hospital for their help in carrying out the project. Financial support was received from the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases, and from the Brazilian Government. RESUME ESSAI CLINIQUE DE PHASE II DE LA MEFLOQUINE CHEZ DES BRtSILIENS DE SEXE MASCULIN Un essai destine a comparer la mefloquine et l'association sulfadoxine-pyrimethamine a et realise de faqon randomi- see en double aveugle sur 97 volontaires adultes de sexe mas- culin originaires d'une region du Bresil oui le paludisme est endemique. Tous ces sujets presentaient un paludisme a falciparum oligosymptomatique ou symptomatique et ont e admis dans le service specialise du paludisme a l'H6pital Barros Barreto, Belem, Bresil. Quarante-neuf sujets ont recu de la m6floquine a raison d'une dose orale unique de 1000 mg, et les autres ont recu de la sulfadoxine-pyrimetha- mine (1500 mg de sulfadoxine et 75 mg de pyrimethamine). Tous les sujets sont restes hospitalises pendant la periode d'etude, soit 66 jours. Dans le groupe traite a la mefloquine, 48 sujets ont pre- sente une reponse de type S; le sujet restant, qui avait vomi 25 minutes apres avoir absorbe le medicament, avait un faible taux de mefloquine dans le sang et a presente une recrudescence le jour 49. Dans le groupe traite a la sulfa- doxine-pyrimethamine, le taux de guerison etait de 73 07o, avec huit cas presentant une reponse de type RI, trois cas une reponse de type RII et deux cas une reponse de type RIII. La disparition de la fievre etait plus rapide avec la 819 820 J. M. DE SOUZA mefloquine (l0007o en cinq jours) qu'avec la sulfadoxine- pyrimethamine (70,607o le jour 7 et 100% le jour 28). L'elimination des formes asexuees de Plasmodium falci- parum des frottis sanguins a eu lieu en quatre jours dans 98%o des cas et etait totale au bout de sept jours avec la mefloquine, tandis qu'avec la sulfadoxine-pyrimethamine les taux d'elimination etaient de 85%7o le jour 4 et de 87,507o le jour 7. Les effets secondaires etaient legers et passagers et consis- taient en cephalees, nausees, vomissements, vertiges et diar- rhees. lus etaient legerement plus frequents avec la meflo- quine, mais n'exigeaient aucun traitement specifique. Ni la mefloquine ni la sulfadoxine-pyrimethamine n'ont eu d'effet sur les gametocytes de P. falciparuin. Dans le groupe traite a la mefloquine, on a observe 11 rechutes dues a P. vivax, la premi&e rechute etant survenue le 42' jour. 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