reviewed by X. Li, Ph. D.
(credential)
Intermittent claudication is a description of a sort of pain in the legs while walking. The pain is felt
after certain walking distance and occurs in the same spot. The pain is gone after a few minutes of rest.
This recurring pain is a sign that the muscles in the legs do not get enough blood to supply needed
oxygen and indicates an early stage of peripheral artery disease (PAD). The underlying cause is
atherosclerosis, a narrowing process of the arteries. As the disease proceeds, the blood vessel becomes
increasingly constricted and blood flow diminishes. When blood flow becomes greatly restricted, tissues
will be starved to death for oxygen and nutrients, and patients may lose the legs.
Peripheral artery disease is difficult to treat. Currently in USA only two drugs, pentoxifylline and cilostazol,
are approved for the treatment. Both drugs have only shown modest benefits at best and have serious side
effects. As numerous experiments showed that ginkgo biloba may increase blood circulation, it is not surprising
that extensive clinical trials have been conducted to study if ginkgo biloba extract may have a role in
treating intermittent claudication and thus peripheral artery disease.
In these trials that were conducted by various medical centers around the world, patients diagnosed
as intermittent claudication were enrolled to receive ginkgo biloba extract or placebo. Most of the trials
involved a relative small number of patients and the largest one had 111 patients1.
However, many of these trials were placebo-controlled, double-blind, and randomized trials
that were supposed to meet the rigor of FDA trial standards. In such trials, patients are randomly
divided into two groups, one group receives the experimental drug and the other receives the dummy.
Neither patients nor researchers know if he or she is taking the drug or dummy.
8 well controlled trials were identified in a systematic and critical analysis of these trials2.
In these 8 trials, totally 415 patients of intermittent claudication were enrolled. Half of them orally
took standardized ginkgo biloba extract at 120 or 160 mg daily for 24 weeks (with two exceptions for 6
and 12 weeks) and the other half took placebo. The key outcome for all trials is "pain-free walking distance",
that is, how far the patient can walk without developing pain in the legs. In the test the patients were
required to walk on a treadmill at a set speed.
Now comes the result. Compared to the trial start, patients from all trials walked some more distance
without pain on average in the trial end, whether the patient took ginkgo or placebo. However,
the ginkgo patients had a greater increase in the mean pain-free walking distance than the placebo
group in 7 out of 8 trials. The mean difference is 34 meters, which is statistically significant2.
In conclusion, currently available trials have provided good evidence that standardized ginkgo biloba extract
can increase the pain-free walking distance in patients of intermittent claudication and may represent
an effective treatment in the early stage of peripheral artery disease.
Reference
1. Peters H, Kieser M, Holscher U. Demonstration of the efficacy of ginkgo biloba special extract EGb 761 on
intermittent claudication--a placebo-controlled, double-blind multicenter trial. Vasa. 1998 May;27(2):106-10.
2. Pittler MH, Ernst E. Ginkgo biloba extract for the treatment of intermittent claudication: a
meta-analysis of randomized trials. Am J Med. 2000 Mar;108(4):276-81.
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