Ginkgo biloba Extract for the Treatment of Intermittent Claudication: A Meta-analysis of Randomized Trials
abstract & commentary
Synopsis: This meta-analysis consisted of eight randomized, placebo-controlled, double-blind trials and found that Ginkgo biloba was superior to placebo for intermittent claudication. However, the size of the effect is modest and of uncertain benefit.
Source: Pittler MH, Ernst E. Am J Med 2000;108:276-281.
Peripheral vascular disease affects many elderly individuals and is an important cause of morbidity and loss of functional independence. Nonsurgical treatment consists largely of smoking cessation, regular exercise, and pharmacologic interventions. Unfortunately, the clinical effectiveness of pharmacologic therapy has been modest. Ginkgo biloba, the top selling medicinal herb in the United States, has been suggested as a potential treatment for peripheral vascular disease because its active ingredients inhibit platelet aggregation, reduce red blood cell aggregation and blood viscosity, and increase the transcutaneous partial pressure of oxygen. Recent studies also suggest that Ginkgo biloba may have vasodilatory effects related to the release of nitric oxide.
In this meta-analysis, Pittler and Ernst identified eight randomized controlled studies that in total examined 415 patients. Of these studies, six trials scored at least 4 points on a 5 point scoring system used to assess the quality of the study. Seven of the eight trials showed weighted mean differences that favored Ginkgo biloba over placebo. Four of these trials had 95% confidence intervals that did not overlap a zero effect, indicating significant differences. Statistical pooling showed an overall increase in pain-free walking distance for Ginkgo biloba compared with placebo (weighted mean 34 meters; 95% CI: 26-43 meters). Doses varied among studies but ranged from 120 mg to 160 mg of Ginkgo biloba daily. Seven studies also reported positive results for maximal walking distance. Side effects from Ginkgo biloba were not reported in three of the studies representing almost half of the studied patients. Minor gastrointestinal complaints (e.g., nausea and dyspepsia) were more common than placebo in the other five studies. The percent of patients with complaints was not reported.
Comment by Martin S. Lipsky, MD
This represents still yet another analysis showing benefit from a herbal medicine. Perhaps we should all drink green tea and take the vitamins our mothers told us to take! Although the effect was modest and its clinical benefit uncertain, on average a 24-week course of 120-180 mg per day of Ginkgo biloba increased pain-free walking distance by 34 meters compared to placebo. This improvement is comparable to pentoxifylline and cilostazol. Ginkgo has the advantage of being less expensive, better tolerated, and safer. Pittler and Ernst conclude that Ginkgo biloba prolongs the pain-free and maximal walking distance in patients with intermittent claudication. Although the overall benefit seems modest, it may represent a reasonable addition to exercise and smoking cessation in patients with intermittent claudication.
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