Complementary medicine: Ginko Biloba

By: Ph. Ali Al-Mehanna

 

Scientific / botanical name
Ginkgo biloba. Family: Ginkgoaceae.

 

Alternative names:
Fossil Tree, Ginkgo Biloba Leaf, Ginkgo Folium, Graine de Ginkgo, Herba Ginkgo Biloba, Japanese Silver Apricot, Kew Tree, Maidenhair Tree, Noyer du Japon, Pei Go Su Ye, Salisburia Adiantifolia, Yen Xing, Yinhsing.

 

Dosage forms:
Orally: tablet, capsules and lozenges.

 
Action:
● Ginkgo leaf might work by protecting tissues from oxidative damage. Ginkgo leaf flavonoids have antioxidant and free radical scavenging properties. The flavonoids seem to prevent or reduce cell membrane lipid peroxidation, and decrease oxidative damage to erythrocytes.
● Ginkgo’s flavonoids also protect neurons and retinal tissue from oxidative stress, and injury following ischemic episodes. Protecting neurons and other tissues from oxidative damage might prevent progression of tissue degeneration in patients with dementia and other conditions.

 
Indications:
● Cognitive impairment and dementia (Alzheimer’s, vascular or mixed dementia)
● Tinnitus
● Peripheral vascular disease
● Anxiety

 
Adverse effects:
● Few cases of gastrointestinal upset, headaches and dizziness were reported.
● Rare case reports of subarachnoid haemorrhage, subdural haematoma, intracerebral
haemorrhage, subphrenic haematoma, vitreous haemorrhage and postoperative bleeding have been documented.

 
Dosage:
● A standardised extract of Ginkgo biloba leaves is a well-defined product and contains approximately 24% flavone glycosides and 6% terpene lactones.
● Products containing EGb761 extract should contain 24% ginkgo flavone glycosides and 6% terpenoids.
Common dose range: Tablets/capsules: 80–240 mg daily of a 50:1 standardised leaf extract in two or three doses has been used in studies.
Dementia syndromes: 120-240 mg per day of ginkgo leaf extract, divided in two or three doses, has been used.
Peripheral vascular disease: 120-240 mg per day of ginkgo leaf extract (EGb 761, Tanakan, Ipsen), divided into two or three doses, has been used; however, the higher dose may be more effective.
Vertigo or tinnitus: 120-160 mg per day of ginkgo leaf extract, divided into two or three doses, have been used.

 

Drug / Disease interactions:
● Anticoagulants (e.g. warfarin), antiplatelet drugs (e.g. aspirin, clopidogrel) and NSAIDs (e.g. ibuprofen): Case reports suggest that concurrent use with drugs that increase clotting time or inhibit platelet function may increase the risk of bleeding, particularly in the older patient. Monitor for bruising or overt bleeding.
● Antiepileptics and seizure threshold–lowering drugs (e.g. prochlorperazine, chlorpromazine): Seizures have been reported in patients taking ginkgo who are predisposed to seizures or on medications that lower the seizure threshold.
● Antipsychotics (e.g. haloperidol, olanzapine) : may reduce the sexual dysfunction side-effects of these drugs and improve sleep continuity; however, results from clinical studies are mixed; possible beneficial interaction.
● Cytochrome P450 substrates : Studies suggest that ginkgo may mildly inhibit CYP1A2, CYP2D6, CYP2E1 and CYP2C9, and induce CYP2C19.

 

Contraindications /precautions:
● If unusual bleeding or bruising occurs, stop use immediately. It may be prudent to suspend use for 1 week prior to major surgery.
● Recent, rare case reports have suggested that ginkgo should be used with caution in people with known risk factors for cerebral haemorrhage and epilepsy until further investigation can clarify its safety.

 
Specific considerations:
● Can cause major bleeding, including subarachnoid haemorrhage.
● Has been reported to increase plasma insulin concentrations in healthy volunteers and decrease insulin concentrations in subjects with type 2 diabetes.

 
Use in:
Pregnancy: theoretically, ginkgo could adversely affect pregnancy as a result of changes in bleeding. Avoid use, as there are insufficient reliable safety data.
Breastfeeding: Insufficient reliable data. Avoiding use is recommended.

 
Evidence for use:
A Cochrane review of RCTs published to September 2007 investigating use of Ginkgo biloba in people with acquired cognitive impairment (including dementia) of any degree of severity found that many of the early trials used unsatisfactory methodology. Subgroup analysis of patients with Alzheimer’s disease (925 from nine trials) showed no consistent pattern of benefit. Most trials studied the standardised extract EGb761.

 
A 2004 Cochrane review of controlled trials identified only three good-quality trials and found no evidence that gingko is effective for tinnitus.

A 2000 meta-analysis of eight RCTs found that Gingko biloba extract (120–160 mg daily) was superior to placebo for the treatment of intermittent claudication. The size of the overall treatment effect was modest and of uncertain clinical relevance.

 
A 2004 systematic review of nine RCTs found that, in the majority of the studies, the standardised ginkgo extract EGb761 increased pain-free walking distance compared with placebo.

 
However, an RCT involving 62 older adults found that 300 mg daily of EGb761 does not significantly improve maximum treadmill walking time in patients with peripheral arterial disease.


Counselling and practice points:

You might experience some side effects, such as gastrointestinal upset, headache, bruising and major bleeding,
while taking this medicine.
Consider stopping before planned surgery (including dental extraction); seek medical advice.
Ginkgo can take up to 4–12 weeks to provide its maximum benefit.

 

Additional resources:
● Pharmaceutical Society of Australia. (2012). Australian pharmaceutical formulary and handbook. (22nd
ed..). Curtin, ACT: Pharmaceutical Society of Australia.
● GINKGO Monograph: Natural Medicines Comprehensive Database. (n.d.). Retrieved May 28, 2015, from
http://naturaldatabase.therapeuticresearch.com/nd/Search.aspx?cs=CEPDA&s=ND&pt=100&id=333&ds=effective

 

References

  • Birks, J., & Grimley Evans, J. (2002). Ginkgo biloba for cognitive impairment and dementia. The Cochrane Library.
  • Hilton, M. P., & Stuart, E. L. (2004). Ginkgo biloba for tinnitus. The Cochrane Library.
  • Pittler, M. H., & Ernst, E. (2000). Ginkgo biloba extract for the treatment of intermittent claudication: a metaanalysis of randomized trials. The American journal of medicine, 1 08 (4), 276-281.
  • Horsch, S., & Walther, C. (2004). Ginkgo biloba special extract EGb 761 in the treatment of peripheral arterial occlusive disease (PAOD)–a review based on randomized, controlled studies. International journal of clinical pharmacology and therapeutics, 42 (2), 63-72
  • Gardner, C. D., Taylor-Piliae, R. E., Kiazand, A., Nicholus, J., Rigby, A. J., & Farquhar, J. W. (2008). Effect of
  • Ginkgo biloba (EGb 761) on treadmill walking time among adults with peripheral artery disease: a randomized clinical trial. Journal of cardiopulmonary rehabilitation and prevention, 28 (4), 258