As a result, patients at risk for heart attacks or strokes who use Plavix to prevent blood clots will not get the full effect of this medicine if they are also taking Prilosec or Nexium. The agency warned yesterday that patients who take Plavix should use different medications to treat acid reflux, such as Mylanta or Zantac.
Prilosec inhibits the drug metabolizing enzyme
Prilosec inhibits the drug metabolizing enzyme (CYP2C19) which is responsible for the conversion of Plavix into its active form (active metabolite), the FDA said. New studies compared the amount of Plavix’s active metabolite in the blood and its effect on platelets (anti-clotting effect) in people who took Plavix and Prilosec versus those who took Plavix alone. A reduction in active metabolite levels of about 45 percent was found in people who received Plavix with Prilosec compared to those taking Plavix alone. The effect of Plavix on platelets was reduced by as much as 47 percent in people receiving Plavix and Prilosec together. These reductions were seen whether the drugs were given at the same time or 12 hours apart, the agency said.
Prilosec is one of a class of drugs known as Proton Pump Inhibitors (PPIs). PPIs are often prescribed to Plavix patients to minimize gastric effects such as nausea and heartburn. According to the FDA, the level of inhibition among other PPIs varies, so it is unknown to what extent other PPIs may interfere with Plavix. However, Nexium, a PPI that is a component of Prilosec, also inhibits CYP2C19 and should also be avoided in combination with Plavix.
The FDA also advised that other drugs that are potent inhibitors
The FDA also advised that other drugs that are potent inhibitors of the CYP 2C19 enzyme would be expected to have a similar effect and should be avoided in combination with Plavix. These include: Tagamet, Diflucan, ketoconazole (sold as Nizoral, Extina, Xolegel, Kuric), VFend, etravirine (known as Intelence or TMC125), Felbatol, Prozac, Luvox, and Ticlid.
The manufacturers of Plavix have agreed to look at other possible drug interactions with Plavix. In the meantime, the Plavix label will be updated with new warnings on Prilosec and other drugs that could interact with Plavix in the same way. When more information becomes available, the FDA will communicate any additional recommendations or conclusions on the use of Plavix.
Finally, the FDA advised patients taking Plavix to consult their healthcare provider if they are currently taking or considering taking Prilosec, Prilosec OTC or Nexium. It is also very important that patients talk with their healthcare professional about any over-the-counter drugs they are taking before starting or while using Plavix. Patients should always consult with their healthcare professional before starting or stopping any medication.