FDA warns heartburn drugs interfere with Plavix

By Ben Hirschler

WASHINGTON (Reuters) - Common heartburn pills Prilosec and Nexium cut the blood-thinning effect of Sanofi-Aventis SA's and Bristol-Myers Squibb Co's heart drug Plavix, U.S. officials warned on Tuesday.

The stomach drugs inhibit a key enzyme and reduce by almost half the anti-clotting effect of Plavix, which is taken by millions of people to reduce the risk of heart attacks and stroke, the Food and Drug Administration said.

Plavix is the world's second-biggest-selling medicine, with global sales of around $9 billion.

The U.S. label for Plavix, known also as clopidogrel, is now being updated with new warnings on the use of AstraZeneca Plc's Prilosec and other similar drugs, including Nexium, the agency said.

Plavix is widely used with such so-called proton pump inhibitors, or PPIs, to reduce stomach acid and avoid gastric problems.

Prilosec is available generically as omeprazole and is also sold over-the-counter (OTC) by Procter & Gamble Co.

The medicine used to be AstraZeneca's top-selling product but has now been overtaken by the company's newer product, Nexium, which sold $5.2 billion in 2008.

Mary Ross Southworth, deputy director for safety in the FDA's division of cardiovascular and renal products, said the problem of interaction between such drugs and Plavix had been highlighted in a new 150-patient study conducted by Sanofi.