Mefloquine, sulfadoxine, and pyrimethamine in the treatment of symptomatic falciparum malaria: a double-blind trial for determining the most effective dose.

A total of 89 adult male Thai patients who had acute, uncomplicated falciparum malaria were treated in a double-blind randomized trial with a single oral dose of two or three tablets, each consisting of 250 mg mefloquine, 500 mg sulfadoxine, and 25 mg pyrimethamine (MSP). The two-tablet regimen produced a cure rate (S response) of 93%, the three-tablet regimen a cure rate of 98%. The mean duration of parasitaemia for the two- and three-tablet groups was 50 and 29 hours, respectively, while the mean duration of fever was 43 and 40 hours, respectively. Differences between the groups were not statistically significant. Tolerance was good at both dose levels. The main side-effects were abdominal discomfort, nausea, vomiting, dizziness, and diarrhoea, but these were mild, transient, and required no specific treatment. The results of haematological and biochemical investigations and of urinalysis revealed no drug-related changes following administration of MSP. The electrocardiograms of some patients revealed sinus bradycardia or sinus arrythmia, but these conditions were transient, symptomless, and clinically not significant.