A randomized, double-blind, placebo-controlled field trial to determine the efficacy and safety of Malarone (atovaquone/proguanil) for the prophylaxis of malaria in Zambia.

Malaria poses a major health risk to people who are exposed to infection in malaria-endemic areas. A randomized, double-blind, placebo-controlled study was conducted to determine the efficacy and safety of Malarone (250 mg of atovaquone/100 mg of proguanil hydrochloride per tablet) for the chemoprophylaxis of Plasmodium falciparum malaria in Zambia. Adult volunteers received a three-day treatment course of Malarone to eliminate pre-existing parasitemia and were then immediately randomized to treatment with either one Malarone tablet daily (n = 136), or one placebo tablet daily (n = 138) for at least 10 weeks. Malaria blood smears were prepared on a weekly basis and a failure of chemoprophylaxis was defined as any subject who had a positive blood smear, or who withdrew from the study due to a treatment-related adverse event. The prophylaxis success rates in the Malarone and placebo groups were 98% and 63%, respectively (P < 0.001). The most commonly reported adverse events with at least a possible causal relationship to study medication were headache and abdominal pain, which occurred with a higher incidence in the placebo group. No subjects were withdrawn from the study due to a treatment-related adverse event. Thus, Malarone appears to have an excellent safety and efficacy profile for the chemoprophylaxis of P. falciparum infection.