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 bas is of the separation is differential extraction of the drugs from plas ma as a function of plasma pH. Hexane extracted ARM from basified plas ma and both ARM and DHA from normal plasma. Derivatized extracts were chromatographed on a 5-mu m ODS column with water-acetonitrile (40:60) as mobile phase and detected at 254 nm. The method removes the need f or expensive absorption cartridges (BondElut). Chromatography has been improved and the elution time shortened in comparison with previous m ethods.