Influence of a 7-day treatment with Ginkgo biloba special extract EGb 761 on bleeding time and coagulation:: a randomized, placebo-controlled, double-blind study in healthy volunteers

During recent years, several case reports have been published in which the authors have voiced their suspicion of a causal relationship between hemorrhagic complications and the intake of Ginkgo biloba preparations. Therefore, a trial was conducted to investigate the influence of Ginkgo biloba special extract EGb 761 on hemostasiological parameters. Fifty healthy, male volunteers underwent 7 days of crossover treatment with 2 x 120 mg/day EGb 761 and placebo in randomized sequence. Between the two treatment phases, a washout-period of at least 3 weeks was inserted. The study's main outcome measures were bleeding time, coagulation parameters, platelet activity in response to various agonists and platelet morphology. The equivalence of the two treatments was analyzed by computing the 90% Fieller confidence intervals for the ratio between the means of the pre-post treatment differences for EGb 761 and placebo, respectively. Treatment safety was investigated by clinical laboratory and vital signs assessment and by adverse events monitoring. Among the 29 coagulation and bleeding parameters assessed, none showed any evidence of an inhibition of blood coagulation and platelet aggregation through EGb 761. Furthermore, the study did not reveal any evidence to substantiate a causal relationship between the administration of EGb 761 and hemorrhagic complications. As regards treatment tolerability, there were no interpretable differences between EGb 761 and placebo except for a slight increase of gastrointestinal complaints during administration of the herbal extract.