Pharmacokinetics study of Erhuang decoction extracts in rats by HPLC–MS/MS

To study the pharmacokinetics of Erhuang decoction extracts, a high performance liquid chromatography-tandem mass spectrometry (HPLC–MS/MS) method was established for the determination of effective substances in rat plasma. The extracts prepared by water extraction (WE) method were given to rats by oral administration. After collected from the orbital venous plexus, plasma was treated by protein precipitation method. Then, the concentration of index components, including baicalin, liquiritin, berberine, palmatine and glycyrrhetinic acid, were determined by HPLC–MS/MS. Gradient elution mode was used to the chromatographic separation with an Inertsil ODS-SP column (100 mm × 2.1 mm, 5 μm), with acetonitrile and 0.1% formic acid containing 10 mmol L−1 ammonium acetate as the mobile phase. MS analysis was conducted by multiple reactions monitoring (MRM) with Electrospray Ionization (ESI). The extraction recoveries of the five active ingredients from plasma were greater than 86.04%, and the intra- and inter-day precisions were less than 16.57%. Results indicated that active ingredients in plasma of rats with oral administration of extracts showed certain difference in the pharmacokinetic parameters, which proved that the active ingredients were effectively absorbed. The established HPLC–MS/MS analytical method was sensitive and accurate, suitable for the pharmacokinetic study of active ingredients in Erhuang decoction.