Ginkgo biloba pharmacokinetic Interaction

An interaction between G. biloba administered as 80 mg leaf extract twice a day and low-dose trazodone (20 mg twice daily) was suspected in a patient with Alzheimer s disease, who took the two products together. It is postulated that a pharmacodynamic (increased gamma-aminobutyric acid-ergic activity) and pharmacokinetic mechanisms [increased metabolism of trazodone to w-chlorophenylpiperazine (w -CPP), which acts on the benzodiazepine-binding sites and releases gamma-aminobutyric acid] contribute to the observed effect (32). Table 2 provides a list of reported pharmacodynamic and pharmacokinetic interactions involving ginkgo. 

Yin OQP, Tomlinson B, Waye MMY, Chow AHL, Chow MSS. Pharmacokinetics and herb-drug interactions experience with Ginkgo biloba and omeprazole. Pharmacogenetics 2004 14 841-850. 

Unger M (2013) Pharmacokinetic drug interactions involving Ginkgo biloba. Drug Metab Rev 45 353-385... 

The pharmacokinetic study involving diclofenac was designed to identify whether Ginkgo biloba exerted an inhibitory effect on cytochrome P450 isoenzyme CYP2C9, which is involved in the metabolism of diclofenac. Although an indication that such an effect may occur was noted in studies in vitro using S-warfarin, the in vivo study did not confirm that this interaction would be seen clinically. ... 

Yoshioka, M., N. Ohnishi, T. Koishi, et al. 2004. Studies on interactions between functional foods or dietary supplements and medicines. IV. Effects of Ginkgo biloba leaf extract on the pharmacokinetics and pharmacodynamics of nifedipine in healthy volunteers. Biol. Pharm. Bull. 27(12) 2006-2009. 

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