Ginkgo Biloba

From Anvita Health Wiki

Contents 1 Introduction 2 Uses 3 Contraindications 4 Dosage 5 Pharmacokinetics 6 Adverse-effects 7 Drug-interactions 8 Mechanism-of-action 9 More General Terms 10 Additional Terms 11 References

Introduction

• An ornamental tree & the oldest species of tree. Medicinal use has been traced back to the Chinese Materia Medica from 2800 BC. The German physician Engelbert Kaempfer was the 1st European to catalog Ginkgo in the late 17th century. It was brought to the US in 1784. Ginkgo is the most resistant of all trees to infection & pollution.

Uses

• Current uses:
• symptomatic treatment of cognitive deficits due to organic brain disease

• Alzheimer's disease
• multi-infarct dementia

• peripheral vascular disease
• headache
• vertigo
• asthma
• tinnitus
• macular degeneration [12]
• no memory benefit for healthy elderly [7,9,11]

Contraindications

• Caution:
• discontinue use prior to surgery (1-2 weeks prior)
• avoid in patients with bleeding disorder
• avoid in patients with seizure disorder

Dosage

• standard extract is 24% flavonoid glycosides

• cognitive impairment:

• 120 to 240 mg of dry leaf extract in 2-3 doses

• peripheral vascular disease

• 120 to 1600 mg of dry leaf extract in 2-3 doses

• capsules 40 mg
• usual dose 40 mg TID
• range 80-240 mg/day
• gingi fluid extract 1:1, 25% alcohol: 1-2 mL TID
• start with low dose & titrate upward to avoid headache
• discontinue 36 hours before surgery [12]

• Active ingredients:

• Ginkgo flavone glycosides & heterosides

• quercetin
• kaempferol
• isorhamnetine

• terpenes
• organic acids
• the leaves are extracted with acetone:water, the organic solvent removed & the extract dried & processed

Pharmacokinetics

• at least 8 weeks of treatment for cognitive impairment
• at least 6 weeks of treatment for peripheral vascular disease
• Ginkgo probably induces CYP2C19

Adverse-effects

• case reports of subarachnoid hemorrhage & hyphemas
• GI distress (common)

• nausea
• diarrhea

• headache (common)

• use a low dose & titrate upward

• no data on safety during pregnancy
• no toxicity reported with leaf
• skin contact with fruit can cause a poison ivy type syndrome
• seizures (case reports); reduces seizure threshold [10]
• anxiety [12]

Drug-interactions

• potential interaction with anticoagulants*

• coumadin
• heparin

• potential interactions with antiplatelet agents*

• non-steroidal anti-inflammatory agents ( NSAIDs)

• anticonvulsive agents
• possible interaction with drugs that lower seizure threshold [6,8]

• antipsychotics, antidepressants, cholinesterase inhibitors, decongestants, sedating antihistamines, systemic steroids, methylphenidate, fentanyl, theophylline, cyclosporine

• tricyclic antidepressants ( TCA)
• trazodone ( Desyrel) in combination may cause CNS depression by overstimulation of GABA receptors [5]
• diminished levels of drugs metabolized by CYP2C19 [8]

• ginkgo decreases omeprazole levels & probably other proton pump inhibitors [8]

• monoamine oxidase inhibitors increase effect & toxicity of ginkgo [12]

• * discontinue 36 hours before surgery [12]
  

• drug interaction(s) of ginko biloba with proton pump inhibitors

Mechanism-of-action

• membrane stabilizing
• free radical scavenger
• enhances cellular uptake & utilization of glucose & O2
• make enhance action of Na+/K+ ATPase
• vasodilation via nitric oxide & prostacyclin
• may enhance venous tone
• inhibits platelet activation, adhesion & degranulation due to direct membrane & antioxidant effects
• increased synthesis of prostacyclin
• antagonist of platelet activating factor ( PAF)
• improved rheological properties of blood
• improvement of hypoxic tolerance

More General Terms

• pharmaceutical herb (medicinal herb)

Additional Terms

• glycoside
• nitric oxide (NO, endothelium derived relaxation factor {EDRF})
• platelet
• platelet-activating factor (PAF)
• prostaglandin I (prostacyclin, epoprostenol {Flolan})
• quercetin
• terpene; polymer of isoprene

References

1. Victoria Rand, UCSF Fresno Lecture, 10/7/98
2. Le Bara et al, JAMA October 1997
3. Kleijnen et al, British J Clinical Pharmacology, 1992
4. Kaiser Permanente, Northern California Regional Pharmacy & Therapeutics Committee
5. Prescriber's Letter 7(9):53 2000
6. Prescriber's Letter 9(2):9 2002
7. Journal Watch 22(18):140, 2002 Prescriber's Letter 9(9):53-54 2002 Solomon PR, Adams F, Silver A, Zimmer J, DeVeaux R. Ginkgo for memory enhancement: a randomized controlled trial. JAMA. 2002 Aug 21;288(7):835-40. PMID: [1]
8. Prescriber's Letter 12(9): 2005 Drug Interactions with Ginkgo Detail-Document#: [2] (subscription needed) [3]
9. DeKosky ST et al Ginkgo biloba for Prevention of Dementia JAMA. 2008;300(19):2253-2262 PMID: [4]
10. Prescriber's Letter 16(1): 2009 Ginkgo for Prevention of Dementia Detail-Document#: [5] (subscription needed) [6]
11. Snitz BE et al Ginkgo biloba for Preventing Cognitive Decline in Older Adults. JAMA. 2009;302(24):2663-2670 <PubMed> PMID: [7] <Internet> [8]
12. Geriatrics at your Fingertips, 13th edition, 2011 Reuben DB et al (eds) American Geriatric Society

Ginkgo biloba