Effects and Mechanism of Action of Panaxnotoginseng Saponins on the Pharmacokinetics of Warfarin

Backgroud The interactions between Chinese herbs and drugs pose a great challenge to the combined clinical application of Chinese herbs and drugs. Chinese medicinal products contain complex pharmacologically active components that may influence the in vivo processes of drugs in a variety of ways. In China, drugs based on Panax ginseng total saponins (PNS) are often combined with warfarin for the treatment of cardiovascular diseases. Objectives To assess the effects of Panaxnotoginseng saponins (PNS) on the pharmacokinetics of warfarin and its mechanism. Method Blood was collected for the determination of the prothrombin time (PT) and international normalized ratio (INR) from rats treated with warfarin alone or with warfarin + PNS. The plasma concentration of warfarin was determined by high-performance liquid chromatography. Western blot was used to detect the expression of cytochrome P450 (CYP) enzymes. Results When warfarin and PNS were co-administered, the PT and INR increased compared to when warfarin was given alone. 72 hours after administration, compared to the warfarin alone group, the warfarin + low-dose PNS, warfarin + medium-dose PNS, and warfarin + high-dose PNS groups showed 110%, 122%, and 126% increases in PT, respectively (all P < 0.05), as well as 111%, 124%, and 128% increases in INR (all P < 0.05). Compared with the warfarin alone group, the clearance rate (CL/F) of warfarin in the warfarin + low-dose PNS, warfarin + medium-dose PNS, and warfarin + high-dose PNS groups was 10% (P > 0.05), 23% (P < 0.05), and 33% (P < 0.05) lower, respectively, while the systemic exposure (area under the concentration-time curve, AUC(0-t)) increased by 106% (P > 0.05), 119% (P < 0.05), and 134% (P < 0.05), respectively, and the blood concentration of warfarin incresed by 112%, 113%, and 114%, respectively (all P > 0.05). After combined treatment of HepG2 cells with warfarin + PNS, CYP1A2 expression was upregulated (P < 0.05) and CYP3A4 was downregulated (P < 0.05) but there was no effect on CYP2C9. In animal experiments, PNS had different effect on the expression of CYP1A2 in different doses. While a low dose of PNS resulted in downregulated CYP1A2 expression (P < 0.05), a medium dose resulted in upregulation (P < 0.05), and CYP1A2 expression was not significantly affected by a high dose of PNS (P > 0.05). Meanwhile, PNS at all doses downregulated the expression of CYP3A4 (P < 0.05) but had no effect on the expression of CYP2C9 (P > 0.05). Conclusion PNS can increase the blood concentration of warfarin, as well as the exposure time, and it can enhance the anticoagulant effect of warfarin by inhibiting the expression of the liver enzyme CYP3A4.