Determination and pharmacokinetic studies of artesunate and its metabolite in sheep plasma by liquid chromatography-tandem mass spectrometry.

A rapid and sensitive high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to simultaneous quantify artesunate and its metabolite in sheep plasma. The plasma samples were prepared by liquid-liquid extraction. Chromatographic separation was achieved on a C18 column (250×4.6mm, 5μm) using methanol: water (60:40, v/v) (the water included 1mM ammonium acetate, 0.1% formic acid, and 0.02% acetic acid) as the mobile phase. Mass detection was carried out using positive electrospray ionization in multiple reaction monitoring mode. The calibration curve was linear from 1ng/mL to 400ng/mL (r(2)=0.9992 for artesunate, r(2)=0.9993 for its metabolite). The intra- and inter-day accuracy and precision were within the acceptable limits of ±10% at all concentrations for both artesunate and its metabolite. The recoveries ranged from 92% to 98% at the three concentrations for both. In summary, the LC-MS/MS metho described herein was fully successfully applied to pharmacokinetic studies of artesunate nanoemulsion after intramuscular delivery to sheep.