Ginkgo biloba extract

Usage

• Medical Conditions: Ginkgo biloba extract is primarily used for cognitive impairment, including memory loss, dementia (Alzheimer’s disease and vascular dementia), and peripheral arterial disease (PAD). It is also used for conditions like vertigo, tinnitus, and intermittent claudication. Some use it for anxiety, but evidence for this use is limited.

• Pharmacological Classification: Ginkgo biloba extract is classified as a herbal remedy, dietary supplement, and in some regions, a phytomedicine. More specifically, it exhibits antioxidant, anti-inflammatory, antiplatelet, and vasodilatory properties.

• Mechanism of Action: The precise mechanism of action of Ginkgo biloba extract is not fully understood, but it is believed to work through multiple pathways. It has been shown to improve blood circulation, scavenge free radicals, reduce inflammation, inhibit platelet aggregation, and modulate neurotransmitter systems.

Alternate Names

• Alternate Names: Ginkgo biloba is sometimes referred to as maidenhair tree. The extract is often standardized as EGb 761.

• Brand Names: Tanakan, Tebonin, Rokan, Ginkgold. Numerous other brand names exist depending on the specific manufacturer and formulation.

How It Works

• Pharmacodynamics: Ginkgo biloba extract improves blood flow by dilating blood vessels and reducing blood viscosity. Its antioxidant properties protect against oxidative stress, which contributes to cell damage. Anti-inflammatory actions are also noted. Effects on cognitive function are likely related to improved cerebral blood flow.

• Pharmacokinetics: After oral administration, the components of Ginkgo biloba extract are absorbed from the gastrointestinal tract. The extract is metabolized primarily in the liver through various pathways, including CYP enzymes. Elimination is primarily through renal excretion, with some biliary excretion. The half-life of ginkgolides and bilobalide, key components, is approximately 4-10 hours.

• Mode of Action (Cellular/Molecular): Ginkgo biloba extract inhibits platelet-activating factor (PAF), reduces nitric oxide breakdown, increases the production of prostacyclin (a vasodilator), and may improve cholinergic neurotransmission.

• Receptor Binding, Enzyme Inhibition: Specific receptor binding has not been fully elucidated, but the extract affects several enzymes, notably those involved in nitric oxide metabolism and lipid peroxidation. It also inhibits phosphodiesterase, which may contribute to its vasodilatory effects.

Dosage

Standard Dosage

Adults: The typical dosage range is 120-240 mg of standardized extract (EGb 761) per day, divided into two or three doses. Treatment duration may range from several weeks to months, depending on the indication.

Children: Ginkgo biloba is generally not recommended for children due to limited safety and efficacy data. Some studies have explored its use in ADHD, with dosages ranging from 60-120 mg twice daily. However, pediatric use should be carefully considered and monitored by a physician.

Special Cases:

• Elderly Patients: Start with a lower dose (e.g., 40 mg three times daily) and adjust as needed based on tolerance and clinical response.
• Patients with Renal Impairment: Dose adjustment may be necessary based on the degree of impairment. Close monitoring is recommended.
• Patients with Hepatic Dysfunction: Use with caution and consider dose reduction, as Ginkgo biloba is metabolized by the liver.
• Patients with Comorbid Conditions: Caution is advised in patients with bleeding disorders, epilepsy, or diabetes. Dose adjustments may be necessary.

Clinical Use Cases

Ginkgo biloba is not typically used in clinical settings like intubation, surgical procedures, mechanical ventilation, ICU care, or emergency situations. Its primary indications are chronic conditions related to cognitive impairment and peripheral circulation.

Dosage Adjustments

Dose adjustments should be made based on individual patient characteristics, including renal and hepatic function, concomitant medications, and response to therapy. Therapeutic drug monitoring is not routinely performed for Ginkgo biloba.

Side Effects

Common Side Effects: Headache, dizziness, nausea, gastrointestinal upset (diarrhea, constipation), allergic skin reactions.

Rare but Serious Side Effects: Bleeding (especially in patients with bleeding disorders or taking anticoagulants), seizures (especially at high doses or in individuals with seizure disorders).

Long-Term Effects: Long-term effects are not well-established.

Adverse Drug Reactions (ADR): Severe allergic reactions (anaphylaxis), spontaneous bleeding, seizures.

Contraindications

• Absolute: Hypersensitivity to Ginkgo biloba or its components.

• Relative: Bleeding disorders, recent surgery or planned surgical procedures, concurrent use of anticoagulants or antiplatelet medications, epilepsy or seizure disorders, pregnancy, breastfeeding.

Drug Interactions

Ginkgo biloba may interact with several medications:

• Anticoagulants/Antiplatelets: Increased risk of bleeding (e.g., warfarin, aspirin, clopidogrel).
• Anticonvulsants: May decrease the effectiveness of anticonvulsants (e.g., carbamazepine, valproic acid).
• Antidepressants: May alter the effects of some antidepressants (e.g., fluoxetine, imipramine).
• CYP450 Substrates: May interfere with the metabolism of drugs metabolized by CYP enzymes.
• Ibuprofen: May increase the risk of bleeding.
• Omeprazole: May decrease the effectiveness of omeprazole.
• Nifedipine: May increase nifedipine levels.
• Diabetes medications: May affect blood sugar control.

Pregnancy and Breastfeeding

• Pregnancy Safety Category: Not established. Generally considered unsafe due to the potential risk of bleeding and premature labor.

• Fetal Risks: Potential for bleeding complications.

• Breastfeeding: Safety not established. Avoid use due to unknown effects on infants.

Drug Profile Summary

• Mechanism of Action: Improves blood flow, antioxidant, anti-inflammatory, antiplatelet.

• Side Effects: Headache, dizziness, GI upset, allergic reactions, bleeding, seizures (rare).

• Contraindications: Hypersensitivity, bleeding disorders, recent/planned surgery, concurrent anticoagulant/antiplatelet use, epilepsy, pregnancy, breastfeeding.

• Drug Interactions: Anticoagulants, anticonvulsants, antidepressants, ibuprofen, omeprazole, nifedipine, diabetes medications.

• Pregnancy & Breastfeeding: Avoid use.

• Dosage: 120-240 mg/day divided doses (adults); not recommended for children.

• Monitoring Parameters: Monitor for bleeding, especially in patients at risk. Observe for signs of allergic reactions.

Popular Combinations

Ginkgo biloba is sometimes used in combination with other nootropics or supplements for cognitive enhancement. However, there are limited clinical trials supporting specific combinations.

Precautions

• General Precautions: Assess for bleeding disorders, recent/planned surgery, allergies, and concomitant medications.

• Specific Populations: See section on “Dosage - Special Cases” and “Pregnancy and Breastfeeding”.

FAQs (Frequently Asked Questions)

Q1: What is the recommended dosage for Ginkgo biloba extract?

A: 120-240 mg/day of standardized extract (EGb 761) in divided doses for adults. Not recommended for children.

Q2: Is Ginkgo biloba safe during pregnancy?

A: No, it is generally considered unsafe due to potential bleeding complications.

Q3: Can I take Ginkgo biloba if I have a bleeding disorder?

A: No, it is contraindicated in patients with bleeding disorders due to increased bleeding risk.

Q4: Does Ginkgo biloba interact with warfarin?

A: Yes, it may increase the risk of bleeding when taken with warfarin.

Q5: What are the common side effects of Ginkgo biloba?

A: Headache, dizziness, gastrointestinal upset, and allergic skin reactions are common.

Q6: Can Ginkgo biloba help with memory improvement?

A: Some studies suggest it may have modest benefits for certain types of cognitive impairment, but more research is needed.

Q7: How long does it take for Ginkgo biloba to work?

A: It may take several weeks or even months to observe potential benefits.

Q8: Can I take Ginkgo biloba with aspirin?

A: Use with caution, as combining it with aspirin may increase bleeding risk.

Q9: Is Ginkgo biloba safe for long-term use?

A: While generally considered safe for adults at recommended doses, long-term effects are not fully characterized.

Q10: Should I stop taking Ginkgo biloba before surgery?

A: Yes, discontinue use at least two weeks prior to any surgical procedure due to the increased risk of bleeding.