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Key
Clinical Points
v Standardized Ginkgo biloba
extract (GBE) may be effective for the treatment of mild cognitive impairment
associated with vascular or neurodegenerative disease.
v GBE may improve symptoms of intermittent
claudication in patients with peripheral vascular disease.
v Ginkgo products should not be combined
with sedatives.
v Ginkgo products should be used with
caution in patients on anticoagulants, including aspirin, due to its potent
platelet-activating factor inhibition.
v Stop GBE 48 hours prior to surgery.
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Indications supported by clinical trials
Effectiveness for
treatment of cognitive impairment (& dementias): Possible.
Many researchers have investigated the efficacy of standardized ginkgo
biloba extract (GBE) in the treatment of Alzheimer’s disease, multi-infarct
dementia and cerebro-organic syndrome.11 In a meta-analysis of 33 randomized,
double-blind studies of the effects of GBE on symptoms associated with
dementia or cognitive impairment, the reviewers ascertained that subjects
who took GBE demonstrated improved cognition, Activities of Daily Living
(ADLs), and emotional functioning as compared with placebo controls.
No information was available on Quality of Life, depression, or dependency
measures.(12) Positive effects are most apparent for subjects with mild
cognitive impairment of vascular or neurodegenerative origin.(19) Some researchers
consider the efficacy of GBE comparable to the cholinesterase inhibitors
though others criticize the comparison as unfounded.(22,23)
Solomon et al., did not find GBE enhanced memory on neuropsychological
tests in healthy elderly volunteers.(24) Other research with healthy subjects
has shown mixed results, though GBE does appear to enhance processing
speed, especially when given with ginseng.(19,25)
Effectiveness for treatment of vertigo, acute deafness:
Possible. I.V. GBE compared favorably with pharmaceutical treatment of
acute hearing loss in 20 patients.(6) GBE has proven effective in the treatment
of vertigo of both vascular and unknown origin in preliminary clinical
trials.(3)
Effectiveness for treatment of eye conditions: Uncertain.
GBE may be useful in the treatment of age-related macular degeneration:
one small study indicated a strong benefit.(26)
In a small study
of patients with normal-tension glaucoma, GBE improved visual field damage.(27)
Effectiveness
for treatment of tinnitus: Uncertain.
Results of at least 6 clinical trials have been contradictory with positive
and negative findings.(2)
Effectiveness
for treatment of other conditions: Uncertain.
In several small clinical trials, GBE was found to reduce the severity
of acute mountain sickness.
A preliminary study of GBE for asthma showed improved pulmonary function
tests- further studies are indicated.(6)
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Preparation and dosage:
Most
clinical studies have used an extract standardized to 24% ginkgo flavonoid
glycosides, 6 % terpene lactones and no more than 5 parts per million
ginkgolic acids.(11)
- For demential syndromes in which reversible causes have
been excluded: 120-240 mg po (given in 2-3 doses per day).(5)
- For claudication: 120-240 mg daily in dvided doses is
standard.
- For vertigo and tinnitus: 120-160 mg daily in divided
doses.(5)
Ginkgold,
Ginkoba, and Ginkai are the brands in this country equivalent to the preparations
used in clinical trials.(11)
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