Efficacy and pharmacokinetics of atovaquone and proguanil in children with multidrug-resistant Plasmodium falciparum malaria

A trial was conducted in 32 Thai children with uncomplicated multidrug-resistant falciparum malaria to assess the efficacy, safety and pharmacokinetics of atovaquone and proguanil; plasma concentrations of atovaquone, proguanil and its metabolite, cycloguanil, were measured in a subset of 9 children. The children received atovaquone (17 mg/kg/d for 3 d) plus proguanil (7 mg/kg/d for 3 d). Twenty-six children who had only Plasmodium falciparum infection and remained in hospital for 28 d were assessed for drug efficacy. The combination regimen produced a cure rate of 100%. Parasite and fever clearance times were 47 h (range 8–75) and 50 h (range 7–111), respectively. Atovaquone and proguanil were rapidly absorbed, with median time to peak concentrations of 6 h (range 6–24) and 6 h (range 6–12), respectively. Peak concentrations of cycloguanil were achieved between 6 and 12 h (median 6) after administration of proguanil. Mean peak plasma concentration of atovaquone on day 3 was 5·1 μg/mL (SD = 2·1). The day 3 mean peak plasma concentration of proguanil was 306 ng/mL (SD = 108) compared with 44·3 ng/mL (SD = 27.3) for cycloguanil. Mean values for the AUC (area under plasma concentration-time curve) were 161·8 μg/mL · h (SD = 126·9) for atovaquone, 4646 ng/mL · h (SD = 1226) for proguanil, and 787 ng/mL · h (SD = 397) for cycloguanil. Terminal elimination half-lives of atovaquone, proguanil and cycloguanil were estimated as 31·8 h (SD = 8.9), 14·9 h (SD = 3·3) and 14·6 h (SD = 2·6), respectively. No major adverse effect was attributable to the study drugs. Atovaquone/proguanil combination is safe and highly effective, and should be especially valuable for treatment of multidrug-resistant falciparum malaria.