Determination of oxymatrine and its active metabolite matrine in human plasma after administration of oxymatrine oral solution by high-performance liquid chromatography coupled with mass spectrometry.

A rapid, sensitive and selective high-performance liquid chromatography mass spectrometric method has been developed and validated for the simultaneous determination of oxymatrine and its active metabolite matrine in human plasma after administration of oxymatrine oral solution. Analytes were extracted from the plasma by liquid-liquid extraction with chloroform. The chromatographic separation was accomplished on a Venusil C18 column (150 mm × 4.6 mm, 5 μm) protected by a C18 guard column (4.0 mm × 2.0 nm; Phenomenex, Torrance, CA, USA). Analytes were detected on a single quadruple mass spectrometer by selected ion monitoring mode via electrospray ionization source. The assay had a lower limit of quantification of 1.5 ng·mL(-1) for oxymatrine and 3 ng·mL(-1) for matrine in plasma. The calibration curves were linear in the measured range. The overall precision and accuracy for all concentrations of quality controls and standards were within ±15%. The proposed method enabled unambiguous identification and quantification of oxymatrine and its active metabolite matrine in vivo. The results provided a meaningful basis for evaluating the clinical applications of the oxymatrine oral solution.