cyp2c9
11 interactions related to cyp2c9
alcohol + warfarin
Alcohol affects warfarin in two opposing ways: acute heavy drinking inhibits hepatic CYP2C9 metabolism of warfarin, raising INR and bleeding risk, while chronic heavy drinking induces enzymes that lower INR and increase clot risk. Alcohol also damages the liver and platelets, compounding bleeding hazards.
phenytoin + st. john's wort
St. John's Wort is a potent inducer of CYP3A4, CYP2C9, CYP2C19, and P-glycoprotein via activation of the pregnane X receptor. Because phenytoin is heavily metabolized by CYP2C9 and CYP2C19, concurrent St. John's Wort can lower phenytoin plasma concentrations into the subtherapeutic range, increasing the risk of breakthrough seizures.
glipizide + berberine
Berberine has potent glucose-lowering activity comparable to metformin and also inhibits CYP2C9, the enzyme responsible for clearing glipizide. The pharmacodynamic stacking plus pharmacokinetic interaction can substantially raise glipizide exposure and produce severe, prolonged hypoglycemia.
warfarin + turmeric
Curcumin, the main active in turmeric, has antiplatelet activity and may also inhibit CYP2C9 metabolism of warfarin, raising warfarin levels. New Zealand Medsafe issued an alert in 2018 after a patient's INR rose above 10 within weeks of starting a turmeric/curcumin product on previously stable warfarin therapy.
cranberry + warfarin
Cranberry juice contains flavonoids that may inhibit CYP2C9, the primary enzyme that metabolizes the active S-enantiomer of warfarin. Multiple case reports describe elevated INR and major bleeding (including fatal hemorrhage) in patients who drank cranberry juice while stably anticoagulated, though randomized trials with smaller doses have not consistently reproduced the effect.
noni juice + warfarin
Noni juice (Morinda citrifolia) products vary substantially in vitamin K content - one published case of warfarin resistance was attributed to a high-vitamin K noni preparation. Noni has also been linked to drug-induced liver injury and may induce CYP2C9, both of which can destabilize warfarin in unpredictable directions.
fluconazole + warfarin
Fluconazole inhibits CYP2C9 and CYP3A4, the enzymes that clear warfarin, and can rapidly raise INR by 50 to 100 percent or more within two to three days of starting, with documented cases of major bleeding and death.
pomegranate + warfarin
Pomegranate juice contains punicalagins and other polyphenols that inhibit CYP2C9 and CYP3A4 in vitro, which would slow warfarin metabolism. Case reports describe both elevated INR (one patient reached INR 14 after heavy consumption) and subtherapeutic INR after stopping habitual juice intake.
sesame seeds + warfarin
Sesame seeds contain lignans (sesamin, sesamolin) that have been shown in vitro to inhibit CYP-mediated 7-hydroxylation of warfarin, which could theoretically slow warfarin clearance. Vitamin K content is low and the clinical relevance of the CYP effect at culinary intake levels has not been demonstrated.
cbd + warfarin
CBD inhibits CYP2C9 (and CYP3A4), the enzymes responsible for metabolizing the more potent S-enantiomer of warfarin. Co-use raises plasma warfarin concentrations, elevates INR, and increases bleeding risk; a published case report required a roughly 30% warfarin dose reduction after the patient started CBD.
hemp seeds + warfarin
Culinary hemp seeds (hulled or whole) contain only trace levels of CBD and very low vitamin K, so they are unlikely to meaningfully shift warfarin's effect. Hemp seed oil products vary widely, and a minority of products have been measured to contain detectable CBD that could theoretically inhibit warfarin metabolism via CYP2C9 at high enough doses.