The Food and Drug Administration warned today that patients taking the blood-thinning drug Plavix should avoid taking the acid reflux medications Prilosec and Nexium because they can interfere with Plavix's activity, reducing its efficacy by half. Plavix, which helps prevent the formation of clots, is usually prescribed after bypass surgery or angioplasty, especially when a stent is implanted to keep arteries open, and is the world's second-best-selling drug (behind the cholesterol-lowering drug Lipitor), with global sales of $8.6 billion per year.
Researchers have been warning about the potential interaction for some time now, but the overall strength of the interaction has not been clear. In January, Sanofi and Bristol-Myers, which distribute Plavix, updated the medication's label to caution against using it with the drugs. A Sanofi spokesman said today that the label would be updated to say that the two heartburn drugs should be avoided altogether.
The FDA said patients who take Plavix and need to reduce acid reflux should take drugs from a different family, such as Mylanta or Zantac. Other drugs that should be avoided for the same reason include Tagamet, Diflucan, Nizoral, Intelence, Felbatol, Prozac, Luvox and Ticlid. The agency said there is not enough data yet to determine if other drugs in the same family as Nexium and Prilosec -- which is sold over the counter by the generic name esomeprazole -- such as Protonix, also present a risk. "There is not enough data to tell us how these drugs interact with" Plavix, Mary Ross Southworth, the FDA's deputy director for safety of cardiovascular products, said at a news conference.
Both Prilosec and Protonix, however, were shown to be dangerous in a study released Monday at the American Heart Assn. meeting in Orlando, Fla. Researchers at Mount Sinai Medical Center in New York studied 8,311 patients who had balloon angioplasty -- in which a catheter is inserted into the coronary artery and a balloon inflated to crush plaque that could otherwise break off and form clots -- and who received a drug-releasing stent to keep the artery open. The researchers found that 17% of the patients were taking either Prilosec or Protonix. During the five years of follow-up, those taking Prilosec or a generic form had a 72% higher risk of death than those not taking any heartburn drugs, while those taking Protonix had a 54% higher risk. Surprisingly, they found no increased risk with Nexium, which has the same active ingredient as Prilosec.
Other studies, however, have given mixed results, with some finding no interaction between the two drugs. The FDA said the new warning came on the heels of a 150-patient study submitted to the agency by Sanofi over the summer that showed the risks.
-- Thomas H. Maugh II
Phorto: Plavix, which is often prescribed after bypass surgery, such as this procedure being performed at Bakersfield Heart Hospital, and heartburn drugs Prilosec and Nexium do not mix, the FDA said today. Credit: Ricardo DeAratanha / Los Angeles Times