UHPLC‐MS/MS–Based Simultaneous Quantification and Pharmacokinetic Characterization of 20 Components of Xiangju Rupining Capsule in Rats

ABSTRACT Xiangju Rupining Capsule (XJRPN) is a Chinese patent medicine clinically used for the treatment of mammary gland hyperplasia. The in vivo pharmacokinetic profiles of its components remain largely unexplored, thereby constraining the elucidation of its pharmacodynamic material basis. Therefore, a rapid and sensitive ultra high‐performance liquid chromatography‐tandem mass spectrometry (UHPLC‐MS/MS) assay was developed and fully validated for the simultaneous quantification of 20 major prototype components in rat plasma following oral administration of XJRPN. The lower limit of quantification (LLOQ) for all 20 target analytes ranged from 0.02 to 2.5 ng/mL. All components exhibited satisfactory linearity ( R 2 ≥ 0.9940), and the intraday and interday accuracy, precision, and stability conformed to the standard acceptance criteria for bioanalytical method validation. Systemic exposure (C max and AUC) varied substantially across different chemical classes. Application of this method revealed diverse pharmacokinetic behaviors among the 20 constituents, providing the first systematic characterization of the in vivo disposition of XJRPN prototype components in rats. This study establishes an essential foundation for clarifying the material basis underlying XJRPN's pharmacological effects and informs strategies for its rational clinical application.