Sanofi-Aventis and Bristol-Myers Squibb have cut a deal with a generic company that could keep a copycat version of their multibillion drug Plavix off the market until 2011.

The two companies have settled patent infringement litigation with Canadian firm Apotex, which won approval in the USA for a generic version of Plavix (clopidogrel) in January, ahead of a scheduled court date in June.

Apotex had said it was free to launch its product because a patent covering Plavix in the USA until 2011 was invalid but, rather than take the risk of losing an expensive legal battle, has accepted a royalty-bearing license for an authorised generic version of the drug once the patent expires, as well as undisclosed payments from both Sanofi-Aventis and B-MS.

The settlement is a major relief for both Sanofi-Aventis and B-MS, as Plavix accounts for a sizeable chunk of both companies’ sales. The product contributed 518 million euros to Sanofi-Aventis' fourth-quarter sales of 7 billion euros last year, while B-MS reported Plavix sales of just over $1 billion out of total revenues of $5 billion in the same period.

The agreement with Apotex does not remove the risk to Plavix, as Indian drugmaker Dr Reddy’s has also mounted a challenge to the US patent on the drug. And if Dr Reddy’s or another generic drugmaker successfully launched a copycat version of Plavix ahead of the patent expiry, Apotex will be free to enter the market. Analysts said the settlement increases the chances that a similar deal could be struck with Dr Reddy’s.

But another potential fly in the ointment for Sanofi-Aventis and B-MS could come if the US federal Trade Commission rejects the settlement on antitrust grounds. “There is a significant risk that required antitrust clearance will not be obtained,” said the two drugmakers in a joint statement, noting that litigation would resume if this occurred.