Determination of bakkenolide A in rat plasma using liquid chromatography/tandem mass spectrometry and its application to a pharmacokinetic study

Abstract

A sensitive rapid analytical method was established and validated to determine the bakkenolide A (BA) in rat plasma. This method was further applied to assess the pharmacokinetics of BA in rats receiving a single dose of BA. Liquid chromatography tandem mass spectrometry in multiple reaction monitoring mode was used in the method, and costundide was used as internal standard. A simple protein precipitation based on methanol was employed. The combination of a simple sample cleanup and short chromatographic running time (2.4 min) increased the throughput of the method substantially. The method was validated over the range of 1-1000 ng/mL with a correlation coefficient > 0.99. The lower limit of quantification was 1 ng/mL for BA in plasma. Intra- and inter-day accuracies for BA were 93-112% and 103-104%, respectively, and the inter-day precision was less than 15%. After a single oral dose of 20 mg/kg of BA, the mean peak plasma concentration (C(max) ) of BA was 234.7 ± 161 ng/mL at 0.25 h. The area under the plasma concentration-time curve (AUC(0-24 h) ) was 535.8 ± 223.7 h·ng/mL, and the elimination half-life (T(1/2) ) was 5.0 ± 0.36 h. In case of intravenous administration of BA at a dosage of 2 mg/kg, the area under the plasma concentration-time curve (AUC(0-24 h) ) was 342 ± 98 h⋅ng/mL, and the elimination half-life (T(1/2) ) was 5.8 ± 0.7 h. Based on the results, the oral bioavailability of BA in rats at 20 mg/kg is 15.7%.