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FDA: Clopidogrel's Antiplatelet Effect Can Be Halved by Omeprazole
The FDA is updating clopidogrel's label to warn against its concomitant use with the proton-pump inhibitor (PPI) omeprazole. The agency says omeprazole can reduce clopidogrel's antiplatelet effect.
New manufacturer-conducted studies indicate that clopidogrel's antiplatelet effect was reduced by nearly 50% in people receiving both drugs. Administering the drugs at different times does not diminish this drug interaction, the FDA warns.
Omeprazole blocks the enzyme CYP2C19, which converts clopidogrel into an active metabolite. Other drugs that should also be avoided in tandem with clopidogrel include cimetidine, fluconazole, ketoconazole, voriconazole, etravirine, felbamate, fluoxetine, fluvoxamine, and ticlopidine. (The agency says it does not yet have enough information to make recommendations about PPIs other than omeprazole, although esomeprazole — a component of omeprazole — should also be avoided with clopidogrel.)
The FDA notes that providers should also make sure that their patients on clopidogrel are not taking over-the-counter versions of omeprazole or cimetidine.
LINK(S):
FDA letter to healthcare professionals (Free)
Clopidogrel prescribing information (Free PDF)
Journal Watch Cardiology summary of earlier study on clopidogrel and PPIs (Free)
Published in Physician's First Watch November 18, 2009
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