Effects ofGinkgo bilobaextract on the pharmacokinetics of bupropion in healthy volunteers

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Abstract
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Bupropion, an antidepressant and smoking cessation drug, is metabolized to its active metabolite hydroxybupropion almost exclusively by CYP2B6.• Ginkgo bilobais among the most commonly used herbal extract in the general population, and is likely to be used by depressed patients receiving bupropion.• Studies have reported thatG. bilobaadministration to rats markedly increased the CYP content and CYP2B mRNA in the liver, and intake ofG. bilobaalso induced various hepatic CYP enzymes, especially CYP2B‐type enzymes.• There may be drug interactions betweenG. bilobaextract and bupropion (CYP2B6 substrate).WHAT THIS STUDY ADDS• Fourteen‐day oral administration ofG. bilobaextract had no statistically significant effect on the pharmacokinetics of bupropion or its active metabolite hydroxybupropion, as measured by AUC, which suggestsG. bilobadoes not significantly affect the metabolism of bupropion following a single oral dose in healthy Chinese men.AIMS: To assess the effects ofGinkgo bilobaextract on the pharmacokinetics of bupropion in healthy volunteers.METHODS: Fourteen healthy male volunteers (age range 19–25 years) received orally administered bupropion (150 mg) alone and during treatment withG. biloba240 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.RESULTS: Ginkgo bilobaextract administration resulted in no significant effects on the AUC0–∞of bupropion and hydroxybupropion. Bupropion mean AUC0–∞value was 1.4 µg·h ml−1[95% confidence interval (CI) 1.2, 1.6] prior toG. bilobatreatment and 1.2 µg·h ml−1(95% CI 1.1, 1.4) after 14 days of treatment. Hydroxybupropion mean AUC0–∞value was 8.2 µg·h ml−1(95% CI 6.5, 10.4) beforeG. bilobaadministration and 8.7 µg·h ml−1(95% CI 7.1, 10.6) after treatment. TheCmaxof 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 thet1/2of 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).CONCLUSIONS: Ginkgo bilobaextract administration for 14 days does not significantly alter the basic pharmacokinetic parameters of bupropion in healthy volunteers. AlthoughG. bilobaextract treatment appears to reduce significantly thet1/2and increase theCmaxof hydroxybupropion, no bupropion dose adjustments appear warranted when the drug is administered orally withG. bilobaextract, due to the lack of significant change observed in AUC for either bupropion or hydroxybupropion.