Mefloquine in the Prophylaxis of P. Falciparum Malaria.

Background: The objectives of this study were (1) to compare the efficacy of Lariam (mefloquine) with that of Fansimef (mefloquine, sulfadoxine, and pyrimethamine), Fansidar (sulfadoxine and pyrimethamine), chloroquine, and placebo in suppressing asexual parasitemia in semi-immune persons living in an area endemic for Plasmodium falciparum malaria; and (2) to compare the tolerance of these drugs when taken over a prolonged period of time. Method: A randomized double-blind comparative placebo-controlled study was undertaken in the village of Biasso, 60 km from Abidjan in the southern part of the Ivory Coast, a region where P. falciparum malaria is endemic. Four hundred and ninety nine male volunteers (five parallel groups), who were inhabitants of Biasso, were involved. The main outcome measures concerned the incidence of malaria breakthroughs (acute malaria attacks) and the incidence of parasitemia. Results: Within this strictly defined epidemiologic context, prophylaxis, taken once weekly, proved to be fully protective (parasitic index: 0) in the Lariam, Fansidar, and Fansimef groups throughout the whole study period. Prophylaxis with chloroquine proved incompletely protective (parasitic index: 2.5) The most frequent side effects were pruritus (5.6%), diarrhea (1.2%) and headache (0.06%). No significant differences in the incidence of side effects in each group (chi-square test) was observed. All side effects were transient and judged to be mild by the investigators. Conclusions: Excellent efficacy was observed in the prophylaxis of P. falciparum malaria with Lariam, Fansidar, and Fansimef as compared to the partial protection provided by chloroquine. Safety and tolerance were comparable in all groups during the whole period of observation (5 months).