Federal health officials said Tuesday a popular heartburn medication can interfere with the blood thinner Plavix, a drug taken by millions of Americans to reduce risks of heart attack and stroke.
The Food and Drug Administration said the stomach-soothing drug Prilosec cuts the blood-thinning effect of Plavix by half.
Regulators said the key ingredient in the heartburn medications blocks an enzyme the body needs to break down Plavix, muting the drug's full effect. Procter & Gamble's Prilosec OTC is available over-the-counter, while AstraZeneca's Nexium is only available with a prescription.
"Patients at risk for heart attacks or strokes who use clopidogrel to prevent blood clots will not get the full effect of this medicine," the agency said in a statement.
Plavix is marketed by Sanofi-Aventis and Bristol-Myers Squibb. With global sales of $8.6 billion last year, it's the world's second-best selling drug behind Pfizer's cholesterol drug Lipitor.
Because Plavix can upset the stomach, it is often prescribed with stomach acid-blocking drugs.
The FDA says patients who need to reduce their acid should take alternative drugs like Johnson & Johnson's Mylanta or Boehringer Ingelheim's Zantac.
A Sanofi spokeswoman said the company has now bolstered that labeling.
"We've strengthened the label to say that these drugs should be avoided altogether, not just discouraged," said Noelle Boyd, Sanofi's senior communications director.
The FDA also warned that users of a range of other drugs, including the antidepressant fluoxetine, known as Prozac, could expect them to interfere with the effects of Plavix.
Other drugs to avoid taking with Plavix include the following medications:
- Cimetidine, marketed as Tagamet and Tagamet HB, used to treat heartburn.
- Fluconazole, marketed as Diflucan, an anti-fungal agent.
- Ketoconazole, an anti-fungal drug marketed under brand names Nizoral, Extina, Xolegel and Kuric.
- Etravirine, a drug used to treat HIV under the brand name Intelence.
- Voriconazole, marketed as Vfend, to treat serious, invasive fungal infections.
- Felbamate, marketed as Felbatol, an anticonvulsant drug used to treat epilepsy.
- Fluvoxamine, marketed as Luvox, an antidepressant used to treat obsessive-compulsive disorder.
- Ticlodipine, marketed as Ticlid, used to treat stroke.