LC-HRMS methods for the quantification of two artemisinin drugs and their metabolites in rat blood and plasma.

As first-line antimalarials used in the artemisinin combination therapy, artemisinin drugs exert their action inside red blood cells. However, the blood pharmacokinetic characteristics of artemisinin drugs have not been fully revealed owing to their built-in chemical instability initiated by Fe released from hemoglobin, with limited information on their metabolites. In this study, liquid chromatography tandem high-resolution mass spectrometric (LC-HRMS) methods were developed for the quantification of two representative artemisinin drugs (artemisinin, ART; dihydroartemisinin, DHA) and their respective metabolite (deoxyartemisinin, D-ART; dihydroartemisinin glucuronide, DHA-Glu) in rat blood/plasma. The blood samples were pretreated with the stabilizer (0.4 m potassium dichromate and 3% EDTA-2Na). The methods displayed excellent specificity, linearity, accuracy and precision for ART (17.7-709.2 nm) and its metabolite D-ART (18.8-751.9 nm), and the linear range was 40.0-4,000.0 nm for both DHA and DHA-Glu. The methods were successfully applied to the pharmacokinetic studies of ART and DHA in rats. The blood-to-plasma ratio was 0.8-1.5 for ART, 1.0-1.5 for D-ART, 1.2-2.2 for DHA and 0.9-1.3 for DHA-Glu, which was time dependent. The results indicated that artemisinin drugs and their metabolites showed a high but different blood-to-plasma ratio, which should be considered when optimizating their dosing regimens or evaluating their clinical outcomes.