THE PHARMACOKINETICS OF ARTEMISININ AFTER ORAL, INTRAMUSCULAR AND RECTAL ADMINISTRATION TO VOLUNTEERS

Abstract— The pharmacokinetics after oral, intramuscular and rectal administration of artemisinin, a new potent antimalarial drug, to healthy volunteers has been examined. The study was set‐up as a four‐way cross‐over design with a wash‐out period of one week between the test days. In ten volunteers artemisinin concentrations in serum were monitored using a reversed phase HPLC assay with UV detection after derivatization. After oral administration, artemisinin was rapidly but incompletely absorbed, the mean absorption time was 0.78 h and the bioavailability relative to the intramuscularly injected suspension in oil 32%. The mean residence time of the latter (10.6 h) was 3 times that of the oral formulation (3.4 h). This seems to enable a twice daily dosage regimen for the intramuscular oil injection, while the oral formulation necessitates a more frequent dosing interval. After intramuscular injection and rectal administration of an aqueous suspension, very low and variable artemisinin concentrations in serum were observed, probably indicating a poor and erratic absorption. 1990 Royal Pharmaceutical Society of Great Britain