A thermostable suppository of artesunate (artesunic acid) has been developed. In Gabon, 12 children with Plasmodium falciparum malaria received two administrations of this suppository in a 4-hr interval. Parasitemia and fever were then measured and the plasma levels of artesunate and its active metabolite, dihydroartemisinin, were determined by means of a reversed phase high-pressure liquid chromatography method using reductive electrochemical detection. Substantial parasite clearance (97-100%) was noted 24 hr after the beginning of the treatment and body temperature had returned to normal. Absorption, metabolism, and elimination of artesunate were rapid. Mean values of maximum plasma levels (Cmax) and maximum concentration peak times (tmax) were evaluated. The Cmax of dihydroartemisinin (0.18 Ϯ 0.10 g/ml [mean Ϯ SE]) was higher than the Cmax of artesunate (0.09 Ϯ 0.04 g/ml) and the tmax of dihydroartemisinin (1.13 Ϯ 0.58 hr) was higher than the tmax of artesunate (0.58 Ϯ 0.19 hr). Plasma levels 30 min after the second suppository administration were not consistently higher than those found 30 min after the first administration.