| 1. By means of a critical review we tried to establish whether there
is evidence from controlled trials in humans on the efficacy of
Ginkgo biloba extracts in cerebral insufficiency. 2. The
methodological quality of 40 trials on Ginkgo and cerebral
insufficiency was assessed using a list of predefined criteria of
good methodology, and the outcome of the trials was interpreted in
relation to their quality. A comparison of the quality was made with
trials of co-dergocrine, which is registered for the same indication.
3. There were eight well performed trials out of a total of 40.
Shortcomings were limited numbers of patients included, and
incomplete description of randomization procedures, patient
characteristics, effect measurement and data presentation. In no
trial was double-blindness checked. Virtually all trials reported
positive results, in most trials the dosage was 120 mg Ginkgo extract
a day, given for at least 4-6 weeks. For the best trials, there were
no marked differences in the quality of the evidence of the efficacy
of Ginkgo in cerebral insufficiency compared with co-dergocrine. The
results of the review may be complicated by a combination of
publication bias and other biases, because there were no negative
results reported in many trials of low methodological quality. 4.
Positive results have been reported for Ginkgo biloba extracts in the
treatment of cerebral insufficiency. The clinical evidence is similar
to that of a registered product which is prescribed for the same
indication. However, further studies should be conducted for a more
detailed assessment of the efficacy.
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