Health watchdogs are looking into whether a drug used by millions to reduce the chances of heart attack and stroke may be less effective with certain patients.
Blood thinner Plavix has consistently come second in the list of best selling worldwide drugs over the past few years, with global sales of around $7.3 billion (£5.3bn).
But the US Food and Drug Administration (FDA) is now looking into reports that certain heartburn medications can neutralise the drug. The agency is also investigating whether Plavix is less effective for patients from certain genetic backgrounds.
The FDA said in both cases, patients may have trouble metabolising Plavix, reducing the drugs ability to prevent blood clots.
Last year, researchers found taking Plavix with popular prescription heartburn drugs significantly increased patients’ chances of ending up in hospital with a heart attack, stroke or chest pains.
It was suggested the heartburn drugs might interfere with a liver enzyme needed to metabolise Plavix, though some heart experts were sceptical of the conclusion.
A statement from the FDA said it is important to determine how the drugs interact because “decreases in the effectiveness of clopidogrel might be avoided, in part, by using other drugs … that do not interfere with its metabolism.”
Copyright Press Association 2009