The U.S. Food and Drug Administration (FDA) is reminding the public that it continues to warn against the concomitant use of Plavix (clopidogrel) and omeprazole because the co-administration can result in significant reductions in clopidogrel’s active metabolite levels and antiplatelet activity. This information was added to the drug label of Plavix in November 2009, and has been the source of continued discussion in the medical literature.¹ 
Patients at risk of heart attacks or strokes, who are given Plavix to prevent blood clots, will not get the full anti-clotting effect if they also take omeprazole. Omeprazole is found in prescription products (Prilosec, Zegerid, and generic products) and over-the-counter products (Prilosec OTC, Zegerid OTC, and generic products).

FDA wishes to emphasize additional facts that may be a source of confusion among healthcare professionals:

• With regard to the proton pump inhibitor (PPI) drug class, this recommendation applies only to omeprazole and not to all PPIs. Not all PPIs have the same inhibitory effect on the enzyme (CYP 2C19) that is crucial for conversion of Plavix into its active form.
• Pantoprazole (Protonix) may be an alternative PPI for consideration. It is a weak inhibitor of CYP2C19 and has less effect on the pharmacological activity of Plavix than omeprazole.

For more information, see FDA’s previous Drug Safety Communication on the Plavix-omeprazole interaction.

¹Bhatt, DL, Cryer, BL, Contant, CF, et al. Clopidogrel with or without Omeprazole in Coronary Artery Disease; NEJM, 2010; epub ahead of print.