Differential extraction of artemether and its metabolite dihydroartemisinin from plasma and determination by high-performance liquid chromatography.

A method is described for the separation of artemether (ARM) from its metabolite dihydroartemisinin (DHA) and determination by HPLC. The basis of the separation is differential extraction of the drugs from plasma as a function of plasma pH. Hexane extracted ARM from basiffied plasma and both ARM and DHA from normal plasma. Derivatized extracts were chromatographed on a 5-microns ODS column with water-acetonitrile (40:60) as mobile phase and detected at 254 nm. The method removes the need for expensive absorption cartridges (BondElut). Chromatography has been improved and the elution time shortened in comparison with previous methods.