Highly sensitive determination of Schisandrin and Schisandrin B in plasma of rats after administration of Wurenchun (Fructus Schisandrae Chinensis Extracts) preparations by LC-ESI-MS/MS.

A sensitive and specific method based on liquid chromatography-tandem mass spectrometry using electrospray ionization (LC-ESI-MS/MS) has been developed for the determination of Schisandrin and Schisandrin B in rat plasma. A 100 microL plasma sample was extracted by methyl tert-butyl ether after spiking the samples with nimodipine (internal standard) and performed on an XTerra(R)MS-C(18) column (150 mm x 2.1 mm, 3.5 mum) with the mobile phase of acetonitrile-water-formic acid (80:20:0.2, v/v) at a flow rate of 0.2 mL/min in a run time of 8.5 min. The lower limit of quantification of the method was 40 ng/mL for Schisandrin and 20 ng/mL for Schisandrin B. The method showed reproducibility with intra-day and inter-day precision of less than 13.8% RSD, as well as accuracy, with inter- and intra-assay accuracies between 93.5 and 107.2%. Finally, the LC-ESI-MS/MS method was successfully applied to study the pharmacokinetics of Schisandrin and Schisandrin B in rats after administration of Wurenchun commercial formulations to rats.