Have Acid Reflux and Blood Clot Risk? FDA explores possible drug interaction

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The Food and Drug Administration on Monday said it has ordered the makers of the clot-reducing drug clopidogrel -- also known as Plavix -- to conduct studies into the possible interaction of Plavix and a class of acid-reflux medicines called proton pump inhibitors. Until those studies have been assessed by the FDA, federal regulators are advising physicians to reconsider whether to start or continue patients on drug therapy that combines the two drugs.

Proton pump inhibitors, which suppress the production of stomach acid, include the prescription drugs Nexium, Prevacid, Aciphex and Protonix. Prilosec is a proton pump inhibitor largely sold over the counter, and FDA urged patients on Plavix who may take any of these drugs to discuss the combination with their physician.

FDA says it was prompted by published reports that clopidogrel is less effective in reducing cholesterol levels in some patients. The agency said genetic factors could play a role, but noted that other drugs may interfere with the body’s metabolism of Plavix, rendering it less effective. FDA said it could be ‘several months’ before it will issue further guidance based on new research.

Plavix is the world’s second-best selling drug, with global sales of $7.3 billion in 2007.

Proton pump inhibitors appear to reduce the breakdown of some drugs by the liver. It may also increase the concentration of diazepam (Valium), phenytoin (Dilantin) and warfarin (Coumadin).

-- Melissa Healy