Effects of Ginkgo biloba extract on the pharmacokinetics of bupropion in healthy volunteers

Abstract

To assess the effects of Ginkgo biloba extract on the pharmacokinetics of bupropion in healthy volunteers. Fourteen healthy male volunteers (age range 19-25 years) received orally administered bupropion (150 mg) alone and during treatment with G. biloba 240 mg day(-1) (two 60-mg capsules taken twice daily) for 14 days. Serial blood samples were obtained over 72 h after each bupropion dose, and used to derive pharmacokinetic parameters of bupropion and its CYP2B6-catalysed metabolite, hydroxybupropion. Ginkgo biloba extract administration resulted in no significant effects on the AUC(0-infinity) of bupropion and hydroxybupropion. Bupropion mean AUC(0-infinity) value was 1.4 microg.h ml(-1)[95% confidence interval (CI) 1.2, 1.6] prior to G. biloba treatment and 1.2 microg.h ml(-1) (95% CI 1.1, 1.4) after 14 days of treatment. Hydroxybupropion mean AUC(0-infinity) value was 8.2 microg.h ml(-1) (95% CI 6.5, 10.4) before G. biloba administration and 8.7 microg.h ml(-1) (95% CI 7.1, 10.6) after treatment. The C(max) of hydroxybupropion increased from 221.8 ng ml(-1) (95% CI 176.6, 278.6) to 272.7 ng ml(-1) (95% CI 215.0, 345.8) (P = 0.038) and the t(1/2) of hydroxybupropion fell from 25.0 h (95% CI 22.7, 27.5) to 21.9 h (95% CI 19.9, 24.1) (P = 0.000). Ginkgo biloba extract administration for 14 days does not significantly alter the basic pharmacokinetic parameters of bupropion in healthy volunteers. Although G. biloba extract treatment appears to reduce significantly the t(1/2) and increase the C(max) of hydroxybupropion, no bupropion dose adjustments appear warranted when the drug is administered orally with G. biloba extract, due to the lack of significant change observed in AUC for either bupropion or hydroxybupropion.