A sensitive LC-MS method for the determination of Sinomenine derivative SWX and its application to pharmacokinetic research in rats.

The goal of this work was to develop a sensitive and accurate method based on high performance liquid chromatography with tandem mass spectrometry (LC-MS) detection for determining the concentration of the Sinomenine derivative SWX in plasma and tissue of rat. Chromatographic separation was achieved on an Agilent SB-C18 (2.1*50 mm, 2.7 µm) column. The mobile phase consisted of acetonitrile (solvent A) and 0.2 % formic acid in water (solvent B) with gradient elution as follows: 0-3 min, 50-90 % A, 3 min-3.01 min, 90-50 % A, 90 % A in 3.01 min-10 min. The flow rate was set to 0.3 mL/min. The column temperature was 40 °C, and the sample injection volume was 10 µL. The calibration curve had good linearity in the range of 10 ng/mL to 600 ng/mL. Biological samples were prepared by protein precipitation with acetonitrile. The area under the curve (AUC) and the peak drug concentration (C) were linearly related to SWX dose. After oral administration of 25, 50 and 100 mg/kg SWX and intravenous administration of 0.5 mg/kg SWX, respectively, the absolute bioavailability of SWX was estimated as 12.4 %, 12.2 % and 10.6 %. SWX was widely distributed in heart, liver, spleen, lung, kidney, brain, breast, and fat, especially in lung, liver, and spleen. Distribution of SWX in brain suggested that it can pass the blood-brain barrier. The method established in this study has the advantages of high recovery and good reproducibility, and was suitable for the determination of the content of Sinomenine derivatives, providing a reliable scientific tool for carrying out pharmacokinetics research, providing a reliable scientific resource.