Cytochrome P450 2C19
Also known as: CYP2C19
Cytochrome P450 enzyme that activates clopidogrel (prodrug) and metabolises proton pump inhibitors (omeprazole, lansoprazole), diazepam and sertraline.
CYP2C19 inhibition (e.g. omeprazole + clopidogrel) reduces formation of the active clopidogrel metabolite and may decrease antiplatelet protection; induction (rifampicin) accelerates substrate metabolism.
Substrates: clopidogrel, omeprazole, lansoprazole, pantoprazole, diazepam, sertraline, citalopram, voriconazole.
Inhibitors: omeprazole, esomeprazole, fluconazole, fluvoxamine, cimetidine.
Inducers: rifampicin, carbamazepine, phenytoin, St John's wort.
Classic interaction: omeprazole (or esomeprazole) + clopidogrel reduces antiplatelet efficacy; prefer pantoprazole when a PPI is needed in a patient on clopidogrel.
DailyMed/FDA (NIH/NLM) — approved labels (clopidogrel, omeprazole); EMC-UK (MHRA) — SmPC
