BACKGROUND: Ginkgo biloba, one of the oldest living tree species, is cultivated worldwide for its medicinal properties and aesthetic appeal. The leaves and seeds are used in traditional medicine to treat respiratory diseases, circulatory disorders, sexual dysfunction, and loss of hearing. The leaf extract is a popular herbal supplement and is promoted extensively for memory loss. Ginkgo is also used by many cancer patients to treat and prevent cancer, and to reduce chemotherapy-associated toxicity. Ginkgo supplements are available as tablets, capsules, and liquid extracts. The dried leaves are used for tea.
RESEARCH: In vitro studies of ginkgo extracts indicate anti-infective,[1] chemopreventive,[2] anticancer,[3] and cytotoxic[4] effects. Epidemiological data indicate that ginkgo may play a role in reducing the risk of ovarian cancer.[5] However, data from the Gingko Evaluation of Memory (GEM) study, in which cancer risk was the secondary outcome, do not support gingko's effectiveness in reducing cancer risk.[6] Studies in patients with gastric cancer showed reduction in tumor area following oral supplementation with capsules of ginkgo exocarp polysaccharides.[4] A combination of an injectable form of ginkgo extract and 5-fluorouracil improved the quality of life of patients with advanced colorectal cancer.[7] Further studies are needed to determine the anticancer potential of ginkgo supplements.
| • | Evidence of an anticancer effect for ginkgo is limited. |
| • | Ginkgo use is associated with adverse effects and it also may interact with prescription medications, such as anticoagulants. |
| • | Data regarding gingko's ability to prevent dementia or Alzheimer disease are conflicting. |
For additional information, visit the Memorial Sloan-Kettering Cancer Center Integrative Medicine Service website, "About Herbs," at http://www.mskcc.org/AboutHerbs.
ADVERSE REACTIONS:Seizures were reported in patients predisposed to seizures or on medications that lower the seizure threshold (eg, prochlorperazine(Drug information on prochlorperazine), chlorpromazine(Drug information on chlorpromazine), perphenazine(Drug information on perphenazine)).[8] Spontaneous bleeding has also been reported.[9,10] Increased viral load was observed in a 47-year-old HIV-infected patient who used gingko along with antiretroviral therapy.[11]
HERB-DRUG INTERACTIONS: When used with NSAIDs, ginkgo may have additive anticoagulant/antiplatelet effects.[12] Ginkgo may cause seizures when combined with medications that lower the seizure threshold.[8] Ginkgo can alter insulin secretion and affect blood glucose levels.[13] Studies show that ginkgo can inhibit and induce the CYP450 1A2, 2D6, and 3A4 enzymes,[14,15] affecting the levels of drugs that are metabolized by these enzymes. Ginkgo inhibits P-glycoprotein and therefore may interfere with drugs that are transported by P-glycoprotein.[16]
