The US Food and Drug Administration (FDA) has fast-tracked an application to extend the indications for Sanofi-Aventis and Bristol-Myers Squibb’s Plavix (clopidogrel) to include the treatment of patients suffering a severe form of heart attack.

The new use - a particularly serious type of heart attack known as acute ST-segment elevation myocardial infarction or STEMI - affects around 500,000 people each year in the USA so would represent a major expansion of the patient population for Plavix. Sanofi-Aventis and B-MS have also filed for this indication in the European Union.

In STEMI, which occurs in a third of all heart attacks, an artery is generally blocked completely for sufficient time to cause heart muscle damage. If approved for this use, Plavix will be suitable for use in all patients with so-called acute coronary syndromes, which also include unstable angina and milder heart attacks known as non-ST segment elevation myocardial infarctions (NSTEMI).

The new indication would add further momentum to a product that is already the fastest growing top brand in the pharmaceutical sector, with sales growth of 31% in 2004 to reach $5 billion. (Growth has since retreated to a level of around 20%, according to IMS Health figures, but Plavix is still advancing faster than its blockbuster peers).

That said, the fast-track comes as a welcome piece of positive news for Plavix, which has had a downturn in fortunes despite its undoubted commercial success.

B-MS and Sanofi-Aventis are due in court in April to try to defend the product against a patent challenge from generics manufacturer Apotex, while the firms suffered a disappointment last November when Plavix seemed to raise the risk of strokes and heart attacks compared to warfarin when given to patients with atrial fibrillation, a major risk factor for stroke.