Quantification of nine bufadienolides of Shexiang Tongxin Dropping Pills in rat plasma and tissues using UPLC-MS/MS and its application to healthy and ischemia-reperfusion rats pharmacokinetic studies

Shexiang Tongxin Dropping Pill (STDP) is a well-known compound preparation used in traditional Chinese medicine for treating cardiovascular diseases. Bufadienolides are the major active compounds of toad venom and are the key to the seven medicinal herbs that comprise STDP. In this study, a reliable and sensitive highperformance liquid chromatography-tandem mass spectrometry method was developed and validated for the quantitative determination of nine bufadienolides (bufalin, gamabufotalin, resibufogenin, marinobufagin, arenobufagin, desacetylcinobufagin, telocinobufagin, hellebrigenin, and hellebrigenol) in rat plasma and tissues (heart and liver). The chromatography column used was a Waters ACQUITY UPLC HSS-T3 column with gradient elution using mobile phase consisting of acetonitrile-water (0.1% formic acid added) at a flow rate of 0.25 mL/ min. This method passed the methodological validation of plasma and tissues and was successfully applied to pharmacokinetic and tissue distribution studies after oral administration of STDP in healthy and ischemiareperfusion (I/R) rats. This indicated that most bufadienolides were well absorbed and quickly distributed in the heart and liver. The area-under-the-curve (AUC)(0_t) of most analytes increased in a dose-dependent manner. Moreover, most of the tested components showed lower plasma and higher tissue concentrations in I/R rats than in healthy rats. The above results on the oral pharmacokinetics and tissue distribution may be helpful for the clinical application of STDP.