Ginkgo biloba

Antioxidant and polyphenol properties.

Improved cognitive performance in pts with Alzheimer disease, particularly short-term visual memory and speed of cognitive processing, for 6 mo to 1 y.

Improved cognitive performance in vascular dementia and may be neuroprotective in pts with preexisting cerebral ischemia.

Used to improve symptoms of intermittent claudication, Raynaud phenomenon, and acrocyanosis. Evidence for effectiveness is debated.

Ginkgo biloba extract (GBE) used in pts with normal-tension glaucoma and those with early diabetic retinopathy, improving measures of colored vision; also possibly effective in treating age-related macular degeneration, symptoms of vertigo and other equilibrium disorders, depression, anxiety, and vitiligo.

GBE is believed to work via the dopaminergic system, which modulates prolactin secretion. One study has shown that it enhances the copulatory behavior of male rats.

Increased risk of bleeding and drug interactions; therefore the ASA recommends stopping 2–3 wk prior to surgery since the half-life of a given ginkgo preparation is unknown.

Lack of safety data in certain populations; therefore not recommended for use in pregnancy, breastfeeding, and in children <12 y of age.

Commonly reported side effects include N/V and diarrhea, headache, and bleeding.

Spontaneous bleeding can occur related to the inhibition of platelet aggregation.

Risk of bleeding is further increased if combined with antithrombotic drugs (aspirin, NSAIDs, clopidogrel, dipyridamole), anticoagulant drugs (heparin, enoxaparin), and other herbal medicines known to increase bleeding (ginger, garlic, ginseng). Recent studies show that coagulation parameters were unchanged when GBE was coadministered with warfarin.

Can decrease the effectiveness of numerous anticonvulsants (valproate, carbamazepine, phenobarbital, primidone, gabapentin, phenytoin); also ginkgotoxin, which is contained in a far greater concentration in the seeds, can cause seizures; anecdotal reports of seizure occurring after pts with and without epilepsy Hx took ginkgo leaf; finally, ginkgo has been shown to decrease alprazolam levels by 17% when GBE 120 mg taken 2 times daily.

May enhance the effects of MAO inhibitors (phenelzine, selegiline, tranylcypromine) and increase the risk of serotonin syndrome when taken with SSRIs.

Interactions have also been reported with CCBs, trazodone, acetylcholinesterase inhibitors, blood glucose–lowering medications, insulin, drugs for erectile dysfunction, and thiazide diuretics.

Animal studies have shown that GBE induces pathologic changes in liver, thyroid gland, and nose, most notably an increase in liver tumors and thyroid gland follicle cell tumors. No human studies to verify these findings.

Ginkgo ( Ginkgo biloba ) is one of the oldest tree species and GBE is one of the most common supplements used worldwide. Several extracts have been isolated.