Bristol-Myers Squibb and Sanofi-Aventis took a beating on Friday after news unraveled that the firms' tie-up with Canadian generics firm Apotex to prevent a copycat version of the clotbuster Plavix (clopidogrel) from being launched before its patent expiry in 2011 had been knocked back by all 50 state attorneys. It's a double blow for the firms, which also announced a criminal probe into the deal by the Department of Justice last week.

Earlier this year, B-MS and Sanofi-Aventis joined forces with Apotex - against which they had previously filed suit for infringement of Plavix' patent ahead of its expiry in November 2011 - under an agreement whereby the Canadian firm would agree not to launch a rival version before this time in return for an undisclosed sum - believed to be an upfront payment of $40 million.

However, the companies were forced to revise this agreement after the Federal Trade Commission voiced its concerns over anti-competitiveness amid a general air of jitteriness that such deals strike out at the generics medicines market. Apotex won the green light of first-to-file approval for its copycat form of Plavix in January and, should the link up with the two pharma giants not go ahead, it could launch any time at its own risk - but clearly could be forced to pay millions back should it lose a litigation case. The first-to-file status gives it 180-days market exclusivity.

Although an earlier announcement from B-MS and Sanofi-Aventis gave a nod to the fact that “there was significant risk that required antitrust clearance would not be obtained,” the decision is still likely to have a negative impact on their respective share prices, with the US giant seeing 2.3% shaved off during after hours trading on the New York Stock Exchange Friday after an 8% fall the day before.

B-MS and Sanofi-Aventis are still awaiting the FTC's decision, but the agreement requires the thumbs up from both the Commission and the state attorney to be cleared. The pharma majors had filed suit against three generics firms looking to launch their Plavix offerings onto the market and it looks likely these could be reinstated, unless a new deal is hashed out that proves more palatable to lawyers and the FTC. However, the original trial date was put on hold when B-MS and Sanofi-Aventis were asked to review their settlement deal with Apotex, and a new date has not yet been set.

In the second quarter of 2006 alone, Plavix broke the $1 billion barrier, bringing $1.1 billion into B-MS' coffers. To lose the world's second biggest drug ahead of patent expiry could add have extensive material effects on the companies' forecasts, particularly B-MS which has just turned the corner of one tumultuous period in its history and last week was looking forward to "a period of sustained sales and earnings growth over several years, beginning 2007," with new product revenues outweighing dramatic losses for several drugs, including its once top-seller Pravachol (pravastatin).