Effect of Xiao-Ai-Ping injection on paclitaxel pharmacokinetics in rats by LC-MS/MS method

Xiao-Ai-Ping injection (XAP) has been shown to be clinically effective in treatment of gastric carcinoma, liver cancer and lung cancer, when it was combined with anticancer drug paclitaxel (PTX). To analyze the effect of XAP on the pharmacokinetics of PTX, a liquid chromatography-tandem mass spectroscopy (LCMS/MS) assay method was developed and validated to quantify PTX simultaneously and its main metabolite 3'-p-hydroxypaclitaxel (C3'-OHP) in rat plasma. PTX and C3'-OHP were quantified using positive MRM mode. The analysis method was validated for specificity, recovery, carry-over, accuracy, precision, sample stability and dilution integrity under various storage conditions. The pharmacokinetic parameters were determined in rats after tail intravenous administration of 6 mg/mL PTX in the absence (control group) or presence of intraperitoneal administration of 10 mL/kg、20 mL/kg XAP (study groups). Compared to control group, the area under the plasma concentration-time curve (AUC) of PTX and C3'-OHP in study groups increased significantly following consecutive administration with XAP for 10 days. In conclusion, pretreatment with XAP enhanced the exposure of PTX and C3'-OHP. There would be herb-drug interaction happening between XAP and PTX in rats.