Magazine article Drug Topics

Plavix-Prilosec Interaction Warning

Magazine article Drug Topics

Plavix-Prilosec Interaction Warning

Article excerpt

Patients taking Clopidogrel (Plavix, Sanofi Aventis/ Bristol-Myers Squibb) and their pharmadsts have a new worry. The Food and Drug Admiriistration (FDA) warned late last year that concomitant use of omeprazole (Prilosec, AstraZeneca, and Prilosec OTC, Procter & Gamble) can reduce the anti-clotting effectiveness of Clopidogrel.

The FDA said recent data submitted by drugmakers' studies show that use of omepra2oie reduces serum levels of clopidogrel's active metabolite by 45 percent and reduces anti -dotting activity by up to 47 percent. Similar reductions were seen whether Clopidogrel and omeprazole were taken at the same time or as much as 12 hours apart.

"Plavix is a critical therapy, preventing stroke, preventing myocardial infarct," said Cynthia Reilly, director of practice development for the American Society of Health System Pharmacists. "Anything that reduces the effectiveness of therapy has to be looked at very cautiously and carefully. "

Plavix labeling is being updated with the new warning. The drugmakers also are conducting follow-up studies to further explore drug interactions with dopidogrel according to the FDA.

Omeprazole inhibits the drug-metabolizing enzyme CYP2C19, which is responsible for the conversion of dopidogrel into its active metabolite. CYP2C19 is part of the cytochrome P450 system, which affects the metabolism of multiple pharmaceutical agents. FDA cautioned that other drugs that are potent inhibitors of the CYP2C19 enzyme should also be avoided in combination with dopidogrel.

These other agents include Cimetidine (Tagamet and Tagamet HB, GlaxoSmithKline), esomeprazole (Nexium, AstraZeneca), fluconazole (Diflucan, Pfizer), ketoconazole (Nizoral, McNeil), voriconazole (Vfend, Pfìzer), etra virine (Intelence, Tibotec), felbamate (Felbatol, Meda), fluoxetine (Prozac, Lilly; Sarafem, Warner Chilcott; and Symbyax, Lilly), fluvoxamine (Luvox, Solvay), and tidopidine (Ticlid, Roche).

The American College of Cardiology (ACC), the American Heart Association (AHA), and the American College of Gastroenterology (ACG) recommend use of gastroprotective agents, specifically proton pump inhibitors (PPIs) such as omeprazole, in patients receiving aspirin, a thienopyridine such as dopidogrel, or both. Other add suppressives can be used, induding misoprostol, sucralfate, histarnine H2-receptor antagonists, and over-the-counter antadds, but PPIs have become a common adjunct to dopidogrel therapy. …

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