FDA Advises Against Use of Clopidogrel With Omeprazole, Other Drugs

The FDA has issued a public health advisory warning consumers to avoid using the stomach acid reducer omeprazole, which is marketed in prescription and OTC formulations as Prilosec, with the anticlotting drug clopidogrel, which is marketed as Plavix.

Clopidogrel's anticlotting effects are contingent on the drug's conversion into its active form with the help of a liver enzyme. Omeprazole blocks the enzyme, reducing the effectiveness of clopidogrel.

The FDA said in information it released for physicians that new study data indicate that clopidogrel's active metabolite levels and, in turn, its anticlotting activity are reduced by nearly one-half when the two medications are taken together. The reductions occurred whether the drugs were taken at the same time or 12 hours apart.

The agency said clopidogrel manufacturers sanofi-aventis and Bristol-Myers Squibb will update their labels to include information about the interaction risks.

FDA officials said several other drugs also should not be used in combination with clopidogrel because they may lead to similar interactions. They are

Although the FDA warns against the use of clopidogrel with cimetidine, the agency said patients using the anticlotting drug can use most other stomach acid reducers -- including ranitidine (Zantac), famotidine (Pepcid) or nizatidine (Axid) -- or OTC antacids, such as Maalox and Mylanta.

In addition, the FDA said it does not have sufficient information about drug interactions between clopidogrel and proton pump inhibitors, other than omeprazole and esomeprazole, to make recommendations about coadministration. However, the agency cautioned physicians to consider all treatment options carefully and to talk with their patients about other OTC medications patients may be taking before beginning treatment.