Federal health authorities on Tuesday issued a public health advisory warning patients and physicians of a potentially serious adverse drug interaction between Plavix, an anti-clotting medication, and Prilosec, which is used to reduce stomach acid. The agency says the warning is based on a yet-to-be-published study that provided evidence that omeprazole, the active ingredient in Prilosec and other popular heartburn drugs, “reduces the pharmacological activity of (clopidogrel-Plavix) if given concomitantly or if given 12 hours apart,” thus increasing the risk of heart attack and stroke.
In most cases, a heart attack or stroke is caused by a blood clot that reduces or blocks the flow of blood through an artery. Plavix helps keep platelets in the blood from sticking together and forming blood clots. It is generally prescribed for people who have suffered a recent heart attack or stroke, or who have been diagnosed with Peripheral Artery Disease (PAD), conditions that increase the risk for future heart attack or stroke. However, because Plavix can cause stomach upset and bleeding, doctors also prescribe acid-reducers such as Prilosec.
Prilosec belongs to a class of drugs called proton pump inhibitors (PPIs). Several previous studies have suggested that PPIs might interfere with Plavix, and the new data confirms it. In fact, the latest study shows that Prilosec lowers the effective of Plavix by half. Mary Ross Southworth, deputy director for safety in the FDA’s division of cardiovascular and renal products, said it believes that the “mechanism of action is because of omeprazole’s activity on the 2C19 enzyme,” which is needed to convert Plavix into its active form in the body. If the action of the enzyme is blocked, less Plavix is available in the bloodstream.
Nexium, Prevacid and Protonix are also PPIs and expected to have the same effect, but the FDA says that at present, it “doesn’t have enough information on other members of the (drug) class to make the recommendation” against their use with Plavix, aside from Nexium.
Additionally, the FDA advised that several other drugs, used to treat a wide range of conditions, could likewise reduce the effectiveness of Plavix, including: fluconazole (Diflucan), ketoconazole (Nizoral), voriconazole (Vfend), etravirine (Intelence), felbamate (Felbatol), fluoxetine (Prozac or Serafem), fluvoxamine (Luvox), and ticlopidine (Ticlid). The agency plans to discuss its investigation into other possible Plavix drug interactions at a meeting of its drug safety oversight board later this month.
The makers of clopidogrel have agreed to further investigate the adverse drug interactions and the labels on Plavix and Prilosec will be updated to include a warning. The label change states that “there is no evidence that other drugs that reduce stomach acid, such as most H2 blockers (except cimetidine (Tagamet), which is a CYP2C19 inhibitor) or antacids interfere with the antiplatelet activity of clopidogrel.”
The FDA suggests that patients taking Plavix who also need something to reduce stomach acid should switch to either antacid tablets such as Maalox, Zantac, or Pepcid, or alternative older drugs like ranitidine and famotidine. The agency also issued the following guidelines for patients taking both Plavix and Prilosec, in which they stressed the importance of patient-doctor communication:
- Both clopidogrel and omeprazole can provide significant benefits to patients, and patients should always consult with their healthcare professional before starting or stopping any medication.
- Patients using clopidogrel should consult with their healthcare provider if they are currently taking or considering taking omeprazole, including Prilosec OTC.
- It is very important that patients talk with their healthcare professional about any over-the-counter drugs they are taking before starting or while using clopidogrel.
By – Madeline Ellis/healthnews.com
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