Effect of Schisandra chinensis extract and Ginkgo biloba extract on the pharmacokinetics of talinolol in healthy volunteers

The authors investigated the effect of herbal medicine Schisandra chinensis extract (SchE) and Ginkgo biloba extract (GBE) on the oral pharmacokinetics of P-glycoprotein substrate talinolol in humans. Twelve healthy male volunteers took a single 100-mg oral dose of talinolol either alone or after pretreatment with 300 mg SchE twice daily or with 120 mg GBE three times daily for 14 days. On day 14, a single 100-mg oral dose of talinolol was administered. Plasma concentrations of talinolol from zero to 24 h were measured by high-performance liquid chromatography. SchE increased the area under the curve (AUC)0-24 of talinolol by 47% (90% confidence interval (CI), 18-84%; p = 0.010), and GBE by 21% (90% CI = 11-32%; p = 0.002). The Cmax of talinolol increased by 51% (90% CI = 21-89%; p = 0.007) with SchE treatment and by 33% (90% CI = 18-51%; p = 0.002) with GBE treatment, respectively. The t1/2 of talinolol increased by 7% (90% CI = -4% to 19%; p = 0.320) with SchE treatment and by 11% (90% CI = -12% to 38%; p = 0.436) with GBE treatment, respectively. The results suggest that both SchE and GBE significantly inhibited P-glycoprotein in humans. Patients receiving either SchE or GBE may require dose adjustments when treated with drugs primarily transported by P-glycoprotein.