[Effect of Coenzyme Q10 and Ginkgo biloba on warfarin dosage in patients on long-term warfarin treatment. A randomized, double-blind, placebo-controlled cross-over trial].

A few case-stories claim that the anti-oxidant Coenzyme Q10 and possibly also Ginkgo biloba interact with warfarin treatment. A decreased response to warfarin in the Coenzyme Q10 cases and an increased response in the Ginkgo biloba case have been described.Twenty-four outpatients on stable, long-term warfarin treatment were included in a randomised, double blind, placebo-controlled crossover trial. Coenzyme Q10 100 mg daily, Ginkgo-Biloba 100 mg daily and placebo were given in random order over treatment periods of four weeks, each followed by a two week wash out period. The international normalized ratio (INR) INR was kept between 2.0 and 4.0 by appropriate adjustment of the warfarin dosage.Fourteen women and ten men, median ages 64.5 years (33-79) were included. Three patients withdrew from the study for personal reasons. The INR was stable during all treatment periods. The geometric mean dosage of warfarin did not change during the treatment periods: Ginkgo biloba 36.7 mg/week (95% confidence interval: 29.2-46.0); CoQ10 36.5 mg/week (29.1-45.8); placebo 36.0 mg/week (28.6-45.1).The study indicated that Coenzyme Q10 and Ginkgo biloba do not influence the clinical effect of warfarin.