Effects of Ginkgo biloba Extract Ingestion on the Pharmacokinetics of Talinolol in Healthy Chinese Volunteers
Background Ginkgo biloba extract (GBE), the best selling herbal medicine in the world, has been reported to inhibit P-glycoprotein in vitro. However, the effects of GBE on P-glycoprotein activity in humans have not been clarified. Objective To investigate the effects of single and repeated GBE ingestion on the oral pharmacokinetics of talinolol, a substrate drug for P-glycoprotein in humans. Methods Ten unrelated healthy male volunteers were selected to participate in a 3-stage sequential study. Plasma concentrations of talinolol from 0 to 24 hours were measured by high-performance liquid chromatography after talinolol 100 mg was administrated alone, with a single oral dose of GBE (120 mg), and after 14 days of repeated GBE ingestion (360 mg/day). Results A single oral dose of GBE did not affect the pharmacokinetics of talinolol. Repeated ingestion of GBE increased the talinolol maximum plasma concentration (Cmax) by 36% (90% CI 10 to 68; p = 0.025), the area under the concentration-time curve (AUC)0-24 by 26% (90% CI 11 to 43; p = 0.008) and AUC0-∞ by 22% (90% CI 8 to 37; p = 0.014), respectively, without significant changes in elimination half-life and the time to Cmax. Conclusions Our results suggest that long-term use of GBE significantly influenced talinolol disposition in humans, likely by affecting the activity of P-glycoprotein and/or other drug transporters.