FDA: Anti-clotting drugs, PPIs may adversely affect each other

ROCKVILLE, Md. Patients taking an anti-clotting drug should avoid the use of a drug for gastroesophageal reflux disease, the Food and Drug Administration warned Wednesday.

The FDA is advising patients using Bristol-Myers Squibb’s and Sanofi-Aventis’ Plavix (clopidogrel) to avoid taking prescription and OTC versions of AstraZeneca’s Prilosec (omeprazole) following data showing that Prilosec’s blocking of a certain liver enzyme may reduce Plavix’s anti-clotting effect by about 50%.

“Both of these drugs, when used properly, provide significant benefits to patients,” FDA Center for Drug Evaluation and Research Division of Cardiovascular and Renal Products scientist Mary Southworth said in a statement. “However, patients at risk for heart attacks or strokes who use Plavix to prevent platelet aggregation will not get the full effect of this medicine if they are also taking Prilosec.”

Plavix is used to prevent blood clots that could lead to heart attacks or strokes. Prilosec, which belongs to the drug class known as proton-pump inhibitors and is available in branded and generic versions, is used to prevent such symptoms of GERD as heartburn. But Prilosec also blocks the liver enzyme CYP2C19, which Plavix needs to be metabolized. It is unknown how other proton-pump inhibitors may interact with Plavix.

The FDA based its decision on studies prompted by reports in January that use of Prilosec could diminish the effectiveness of Plavix.