A SENSITIVE LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRIC ASSAY FOR THE DETERMINATION OF ARTEMETHER AND ITS ACTIVE METABOLITE DIHYDROARTEMISININ IN HUMAN PLASMA

This paper describes a simple, rapid and sensitive liquid chromatography / tandem mass spectrometry (LC–MS/MS) assay method for the simultaneous quantification of artemether and its active metabolite, dihydroartemisinin in human plasma samples. Nevirapine was used as an internal standard. Analytes and the internal standard were extracted from 200 µL of human plasma via liquid-liquid extraction technique using tert-butyl methyl ether. The chromatographic separation was achieved on a C18 column by using a mixture of methanol and 5mM ammonium acetate buffer (90:10, v/v) as the mobile phase at a flow rate of 0.85 mL/min. The calibration curve obtained were linear (r 2  0.99) over the concentration range of 1.00-204.50 ng/mL for artemether and 0.51-161.52 ng/mL for dihydroartemisinin. Method validation was performed as per US FDA guidelines and the results met the acceptance criteria. A run time of 3.5 min for each sample made it possible to analyze more number of plasma samples per day. The proposed method can be applicable to clinical studies in humans.