An HPLC-MS/MS method for the quantitative determination of platycodin D in rat plasma and its application to the pharmacokinetics of Platycodi Radix extract

AimsTo develop an HPLC-MS/MS method for the quantification of platycodin D (PD) in rat plasma, and to acquire the main pharmacokinetic parameters of PD after oral administration of pure PD or of Platycodi Radix extract (PRE) containing PD.MethodPlasma samples were pretreated with solid-phase extraction using an Oasis® HLB SPE cartridge. Madecassoside was used as the internal standard (IS). Chromatographic separation was achieved on an ODS column (100 mm × 2.1 mm i.d., 3.5 μm) with a mobile phase consisting of acetonitrile/water (30 : 70, V/V) containing 0.1 mmol·L−1 ammonium acetate at a flow rate of 0.25 mL·min−1. The detection was performed on a triple quadruple tandem mass spectrometer using an electrospray ionization (ESI) source with a chromatographic run time of 3.0 min. The detection was operated by multiple reaction monitoring (MRM) of the transitions of m/z 1 223.6→469.2 for PD and of m/z 973.6→469.2 for madecassoside (IS), respectively.ResultsThe calibration curve was linear from 5 to 2 000 ng·mL−1 (r2 >0.99) with a lower limit of quantification (LLOQ) of 5 ng·mL−1. The intra- and inter-day precision (relative standard deviation, RSD) values were below 15% and the accuracy (relative error, RE) was from −15% to +15% at three quality control (QC) levels. Plasma concentrations of PD were determined for 24 h after i.v. administration of PD, and oral administration of PD and PRE, respectively. The absolute oral bioavailability of PD in rats was found to be (0.48 ± 0.19)% when administered PD, and to be (1.81 ± 0.89)% when administered PRE.ConclusionThe developed HPLC-MS/MS method was successfully applied to assess the pharmacokinetic parameters and oral bioavailability of PD in rats after administration of PD and Platycodi Radix extract.