Ginkgo biloba leaf extract is the i...

Ginkgo biloba leaf extract is the in the greatest degree widely sold phytomedicine in Europe where it is used to treat the symptoms of early-stage Alzheimer's disease, vascular dementia, peripheral claudication, and tinnitus of vascular origin. It also is common of the 10 best-selling herbal medications in the United States. (1) There are throughout 120 published clinical studies forward ginkgo, primarily from Europe. The standardized preparation of Ginkgo biloba extract is EGb 761 In the United States, ginkgo is classified as a dietary supplement; the American brands that are comparable with EGb 761 that have been make subordinateed to clinical studies are Ginkgold, Ginkoba, and Ginkai. (2) Standardized preparations contain 24 percent ginkgo flavonoid glycosides, 6 percent terpene lactones, and no more than 5 parts for million ginkgolic acids. (1,2)

Pharmacology

The mechanism of action of ginkgo is believed to be produc through its functions as a neuroprotective agent, an antioxidant, a free-radical scavenger, a membrane stabilizer, and an inhibitor of platelet-activating factor via the terpene ginkgolide B (3-6) Other pharmacologic tenors include the following: endothelium relaxation mediated at inhibition of 3',5'-cyclic GMP (guanosine monophosphate) phosphodiesterase (78); inhibition of age-related los of muscarinergic cholinoceptors and a-adrenoceptors; and stimulation of choline uptake in the hippocampus. (19) Ginkgo extract also has been shown to inhibit beta-amyloid deposition. (10)

Uses and Efficacy

CEREBROVASCULAR DISEASE, DEMENTIA, AND MEMORY ENHANCEMENT

A systematic review (11) of eight randomized, double-blind, placebo-controlled studies conclud that ginkgo had becoming effects on improving the symptoms of dementia and cerebral insufficiency equivalent to pharmacologic therapy with ergoloid mesylates (Hydergine). A later meta-analysis reviewed 50 articles to examine the result of ginkgo on objective measures of cognitive function in patients with Alzheimer's disease. (12) [Evidence on a level A, meta-analysis] Four of these studies met inclusion criteria for adequate clinical trial design. (13-16) In the 212 controls in the placebo and ginkgo arranges a significant overall effect size was originate that was comparable with the benefits of donepezil (Aricept). (17) Efficacy was measured using the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog) and other standardized measures of cognition.

A review (18) of studies of at least six month in duration demonstrated that ginkgo extract and second-generation cholinesterase inhibitors were equally effective in treating mild to moderate Alzheimer's dementia. A systematic review (19) of nine studies onward ginkgo use showed a safe and positive power beyond placebo, but the investigators remained tentative in recommending it for treatment of dementia until better studies are careered A Cochrane meta-analysis of 33 trials conclud that ginkgo appears to be safe, and showed promising evidence of improvement of cognition and function among patients who received the herb. However, the three fresh trials showed inconsistent results, suggesting that a large trial with recent methodology is needed to answer questions about treatment powers (20) [Evidence level A, meta-analysis]

single of the studies analyzed in the Cochrane review (20) was a Dutch subject of attention (21) of 214 patients through the whole extent of 24 weeks using a medium dosage of ginkgo (160 mg by means of day), a high dosage of ginkgo (240 mg by means of day), or placebo in a crossover design. This investigation failed to show improvement in age-associated memory impairment or mild or moderate dementia in several neuropsychologic and behavior result measures. (21) However, this contemplation included patients with age-associated memory impairment rather than just ones with dementia, which may have limited the statistical power of its conclusions about the part of ginkgo in dementia. (22)

A randomized, placebo-controlled trial (23) of the validitys of ginkgo in healthy, noninstitutionalized adults without dementia or other known mental deficit institute no benefit from six weeks of ginkgo therapy (120 mg by day) on several standardized neuropsychologic measures of memory and learning. However, a consideration (24) using a similar design with a higher dosage of ginkgo (180 mg by day) showed clinically significant cognitive benefits in healthy persons

The National Institutes of Health and the National Center for Complementary and Alternative Medicine have sponsored a multi-center, six-year, randomized, two-arm, double-blind, placebo-controlled trial of 2000 patients. The trial will evaluate the safety and efficacy of ginkgo in preventing dementia and age-related cognitive decline and is generally underway and headed by investigators at the University of Pittsburgh. Another phase III trial is underway at the Oregon Health Sciences Center Portland, to studious mood the effects of ginkgo onward cognitively intact elderly patients older than 85 years, and the consequence on their progression to mild cognitive impairment. This investigation will use volumetric quantitative magnetic resonance imaging measures of brain size and peripheral oxidative markers.