A validated LC-MS/MS method for the determination of specnuezhenide and salidroside in rat plasma and its application to a pharmacokinetic study.

The aim of this study was to establish and validate a rapid and sensitive LC-MS/MS method for the simultaneous determination of specnuezhenide and its bioactive metabolite salidroside in rat plasma. Protein precipitation was carried out and the analytes were separated on a Waters Acquity UPLC HSS T3 column (2.1 × 100 mm, 1.8 μm). A mobile phase consisting of acetonitrile and 0.1% formic acid aqueous solution was used for elution under gradient conditions at a flow rate of 0.4 mL/min. Quantification was performed in the negative multiple reaction monitoring mode with precursor-to-product transitions at m/z 685.2 → 453.1 for specnuezhenide, m/z 229.3 → 119.0 for salidroside and 493.2 → 147.1 for the internal standard. The method showed good linearity, accuracy, precision and stability in the range 0.5-500.0 ng/mL for specnuezhenide and salidroside. The values of the matrix effect were within the range of 100.02-111.87% for both analytes, while the mean extraction recovery was within the range 64.19-78.26%. The intra- and inter-day precisions (RSD) were <13.49% and the accuracy (RR) ranged from 93.59 to 102.24%. This study was successfully utilized for the pharmacokinetic study of specnuezhenide in rats after oral and intravenous administration. The oral bioavailability of specnuezhenide was 1.93%.