Ginkgo

Ginkgo biloba contains ginkgolides (especially ginkgolide B) which are potent PAF (platelet-activating factor) receptor antagonists, inhibiting platelet aggregation. Additionally, bilobalide and flavonoids may inhibit thromboxane synthesis. Multiple case reports of serious bleeding events (intracranial hemorrhage, hyphema) with concurrent warfarin or antiplatelet use have been documented.

Avoid concurrent use of high-dose Ginkgo with warfarin. If patient insists on use, monitor INR closely, particularly during initiation and discontinuation. Advise discontinuation at least 2 weeks before any surgical or invasive procedure.

Additive antiplatelet effect: Ginkgo ginkgolide B inhibits PAF-induced platelet aggregation while aspirin irreversibly inhibits COX-1/thromboxane A2 synthesis. Combined antiplatelet effect significantly increases bleeding risk. Case reports include spontaneous subdural hematoma and bilateral subdural hematomas after ginkgo + aspirin use.

Use with caution. Patients on antiplatelet therapy should inform their clinician before adding Ginkgo. Monitor for unusual bruising or bleeding. Discontinue Ginkgo at least 2 weeks before elective surgery.

Ginkgo inhibits CYP2D6 and potentially CYP3A4, which are both involved in trazodone metabolism. A published case report described a patient who fell into a coma after taking Ginkgo with trazodone, attributed to elevated trazodone plasma levels. The exact CYP mechanism is plausible but not fully elucidated.

Monitor for excessive sedation and trazodone-related adverse effects (orthostatic hypotension, priapism) if used concurrently. Consider a lower trazodone dose. Counsel patient about this interaction.

Ginkgo seeds (but less so standardized leaf extracts) contain the neurotoxin 4-O-methylpyridoxine (ginkgotoxin), a vitamin B6 antagonist that can lower the seizure threshold and reduce the effectiveness of anticonvulsant medications. Additionally, Ginkgo may induce CYP2C19, affecting carbamazepine and phenytoin metabolism.

Use standardized EGb 761 leaf extract, not seeds. Caution in patients with epilepsy, especially those on narrow-TI anticonvulsants. Monitor seizure control carefully. EEG monitoring may be warranted in high-risk patients.

Ginkgo biflavonoids may inhibit CYP3A4 and P-glycoprotein in vitro, potentially increasing cyclosporine bioavailability. However, some in vivo data suggest possible CYP3A4 induction with long-term use. The net effect is unpredictable; in transplant patients on cyclosporine, any fluctuation in drug levels is dangerous.

Avoid in transplant patients on cyclosporine or tacrolimus. If use is unavoidable, perform frequent TDM of the immunosuppressant and monitor renal function. Advise patients to inform transplant coordinators of any herbal supplement use.

Ginkgo inhibits CYP2D6 activity, which is the primary metabolic pathway for many SSRIs including fluoxetine, paroxetine, and fluvoxamine. Inhibition of CYP2D6 increases SSRI plasma concentrations. Additionally, some in vitro data suggests mild monoamine-modulating activity for ginkgo flavonoids, potentially adding to serotonergic tone.

Monitor for increased SSRI adverse effects (nausea, agitation, sexual dysfunction) when Ginkgo is co-administered. Consider checking plasma levels of CYP2D6-sensitive SSRIs. Counsel patient to report any new or worsening symptoms.

Ginkgo biloba has been shown to have an elevating effect on blood sugar levels via inhibition of insulin secretion in animal models. In diabetic patients, this may counteract antidiabetic therapy and increase blood glucose. Close monitoring of blood glucose levels is recommended per StatPearls clinical review.

Monitor blood glucose more frequently in diabetic patients starting ginkgo; antidiabetic medication may need dose adjustment upward. Alert patients and their diabetologist about this interaction to avoid hyperglycemia complications.

Ginkgolides (especially ginkgolide B) are potent platelet-activating factor (PAF) antagonists that inhibit PAF-mediated platelet aggregation. Combined with clopidogrel or aspirin, additive antiplatelet effects are produced. A retrospective observational study of 2,647 prescriptions found clopidogrel and aspirin had the highest interaction prevalence with Ginkgo biloba extract (2.61% each), with increased bleeding risk (OR 1.08, p<0.001).

Monitor for excessive bleeding (bruising, prolonged bleeding time, GI bleeds) in patients on antiplatelet therapy using ginkgo. Discontinue ginkgo at least 2 weeks before surgery or invasive procedures. Inform cardiologists and surgeons about ginkgo use.

Ginkgo biloba has weak MAO inhibitory properties. Co-administration with SSRIs may result in reduced antidepressant efficacy. In a triple-blind, placebo-controlled trial, EGb 761 showed no statistically significant improvement in antidepressant-induced sexual dysfunction. Mayo Clinic notes that ginkgo with certain antidepressants such as fluoxetine (Prozac) might keep them from working as well.

Monitor therapeutic response to antidepressants in patients concurrently using ginkgo; consider alternative approaches for depression if efficacy appears reduced. Monitor for serotonin syndrome when ginkgo is combined with antidepressants given its weak MAO inhibitory properties.

Ginkgo extract at doses higher than the recommended 240 mg/day may induce CYP3A4-mediated drug metabolism; clinical pharmacokinetic studies show that high-dose GLE produced weak induction of midazolam hydroxylation. Taking ginkgo with simvastatin may reduce statin plasma concentrations via CYP3A4 induction, reducing therapeutic efficacy.

Monitor lipid levels in patients taking CYP3A4-metabolized statins concurrently with ginkgo; dose adjustment of statin may be required if lipid targets are not met. Use rosuvastatin (non-CYP3A4 substrate) as an alternative if this interaction is a clinical concern.

The retrospective observational study of Ginkgo biloba prescriptions found significant interaction prevalence with direct oral anticoagulants (DOACs), documented in 20 prescriptions. Ginkgo PAF-antagonist and platelet-inhibitory properties add to the anticoagulant effect of DOACs, increasing bleeding risk. Significant correlations were found between Ginkgo drug interactions and both bleeding risk (OR 1.08) and abnormal coagulation (OR 1.49).

Avoid concurrent use of ginkgo with DOACs where possible; if combination is unavoidable, monitor closely for bleeding signs (hematuria, bruising, GI bleeding). Inform patients that this combination significantly increases hemorrhage risk. Discontinue ginkgo before surgery.