Ginkgo biloba is the oldest living tree species. The Chinese have been using it medicinally for millennia. In recent years, the use of ginkgo biloba has experienced growing popularity. Ginkgo products should be standardized to provide at least 24% flavone glycosides and contain at least 6% terpene lactones. A 2002 examination of US marketed gingko products found that some products failed to meet the standards that were claimed on the bottle. Therefore caution is advised in product selection.

The ginkgolide class of chemicals has not been found in any other living species to date. The overall physiologic results of ginkgo use are increased perfusion to the brain and peripheral circulation, enhanced free radical scavenging, improved cerebral tolerance to hypoxia, and strengthened microvasculature.

Ginkgo products are sold over-the-counter throughout the world and by prescription in Germany and France. Ginkgo extracts are used for almost any type of vascular disorder associated with spasms, hypoxia, and free radical damage.

Ginkgo has been used successfully in Raynaud's disease, varicose conditions, dementia syndromes, vertigo and tinnitus of vascular origin, peripheral arterial occlusion, platelet aggregation, and intermittent claudication. Ginkgo is also being investigated for its use immediately after stroke, in asthma, in sexual dysfunction, and in depressive disorders.

Dosage
The typical daily dose of ginkgo biloba for dementia syndromes is 120 to 240mg of a standardized extract. The higher doses are generally required for cerebral disorders. A suggested titration for Alzheimer's dementia would be 60mg bid for 6 weeks, then increasing the total daily dose by 40 to 60mg every 8 weeks if improvements are not visible.

The daily dose for intermittent claudication, Raynaud's disease, varicose conditions, and all other previously mentioned disorders is 120 to 180mg. The daily dose should be 60mg bid or tid, because flavones and terpenes have a short half-life. Patients should allow at least 6 to 8 weeks of therapy before maximal benefits are observed.

Adverse Effects
Adverse effects related to ginkgo are relatively mild and infrequent and include headache, diarrhea, dizziness, and occasional allergic dermatologic reactions. However, rare cases of hematomas and bleeding have been reported. Ginkgo's antiplatelet effect should be considered if the patient is taking other agents with similar blood-thinning actions.

A ginkgo biloba extract (80mg of extract EGb 761 BID) strongly prevented altitude sickness in a trial of 44 people climbing to 17,550 feet. No one in the ginkgo group developed acute altitude sickness, while 40% of those in the placebo group did. [Aoiat Space Enoiron Med 1996;67: pp.445-452]