The pharmacokinetics of artemisinin suppositories in Vietnamese patients with malaria.

Eight male Vietnamese malaria patients received 600 mg of artemisinin in a single dose of 3 suppositories containing 200 mg each; 24 h later they received a single oral dose of mefloquine, 15 mg/kg. Plasma artemisinin concentrations were measured until 24 h after dosing, and parasites were counted until none could be detected. Artemisinin concentration versus time curves of all subjects were analysed with model-independent methods. Mean Cmax was 108 micrograms/L (SD = 60, range 29-169), mean tlag was 0.3 h (SD = 0), mean tmax was 6.5 h (SD = 3.9, range 2-14). By comparing the area under the concentration-time curve with that found in a previous study on oral artemisinin, average bioavailability relative to oral administration was estimated to be approximately 30%. Median parasite clearance time was 24 h (range 24-72). We concluded that therapeutic blood concentrations of artemisinin can be reached after rectal administration. There was a large inter-individual variation in blood concentrations attained. The dose given by rectal administration should probably be twice the usual oral dose, i.e., at least 20 mg/kg of body weight twice daily.