cyp2c19
8 interactions related to cyp2c19
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.
phenytoin + ginkgo
Ginkgo biloba induces CYP2C19, the primary enzyme responsible for phenytoin metabolism. A published case report described a fatal breakthrough seizure in a patient on phenytoin and valproate whose autopsy revealed subtherapeutic anticonvulsant levels and self-administration of ginkgo biloba. Ginkgo also has independent pro-convulsant potential at high doses and through ginkgotoxin contamination.
propranolol + st. john's wort
St. John's Wort potently induces CYP1A2 and CYP2C19 along with CYP3A4 and P-glycoprotein, accelerating the metabolism of propranolol and reducing its plasma levels. Documented cases include loss of intraocular pressure control in glaucoma patients on topical beta-blockers, and the mechanism predicts similar loss of antihypertensive and antiarrhythmic effect with systemic propranolol.
cbd + sertraline
CBD inhibits CYP2C19, an enzyme that contributes to sertraline metabolism. A published case report describes severe hyponatremia and cognitive dysfunction in a CYP2C19 intermediate metabolizer who added over-the-counter CBD to chronic sertraline, consistent with phenoconversion to a poor-metabolizer phenotype.
cannabis + ssris
Cannabis cannabinoids inhibit CYP2C19, CYP2C9, and CYP3A4, raising plasma levels of SSRIs such as sertraline, citalopram, and escitalopram. Cannabinoids also modulate serotonin signaling, and case reports describe serotonin syndrome precipitated by high-potency cannabis in patients on SSRIs.
omeprazole + st. john's wort
St. John's wort potently induces CYP3A4 and CYP2C19, the enzymes responsible for omeprazole metabolism. Co-administration significantly lowers omeprazole plasma concentrations, reducing its acid-suppressing efficacy and potentially compromising treatment of GERD, ulcers, or H. pylori eradication.
escitalopram + st. john's wort
Escitalopram is a highly selective SSRI metabolized largely by CYP2C19 and CYP3A4. St. John's wort independently inhibits serotonin reuptake and strongly induces these same enzymes plus P-glycoprotein. Combined use risks serotonin syndrome and can also lower escitalopram plasma levels, blunting its antidepressant effect.
cbd + clobazam
CBD strongly inhibits CYP2C19, the enzyme that clears N-desmethylclobazam (the active metabolite of clobazam). Co-administration triples plasma N-desmethylclobazam levels, causing excess sedation, ataxia, and somnolence; this is documented in the FDA-approved Epidiolex prescribing information.