Bristol-Myers Squibb and Sanofi-Aventis won a crucial legal victory on Thursday when a federal judge ordered a halt to sales of a generic version of the US and French drugmakers’ blockbuster drug, Plavix.

However, the judge refused to order a recall of the generic drug already sold since August 8, when Apotex, a Canadian drugmaker, launched it in spite of unresolved patent litigation.

The judge set a trial date of January 22 to decide Apotex’s claims that the Plavix US patent is invalid and unenforceable, against claims by Bristol and Sanofi that the patent is valid until at least 2011.

The injunction against generic Plavix sales is likely to lift shares of Bristol and Sanofi, whose financial outlooks depend heavily on the blood-thinner, which had US sales last year of about $4bn.

It also could give a lift to the fortunes of Peter Dolan, Bristol’s embattled chief executive. Apotex’s aggressive tactics against Bristol’s attempts to negotiate a settlement to delay its generic launch, and potential mistakes to secure Plavix’s future have raised questions about Mr Dolan.

Bristol and Sanofi in March reached a settlement with Apotex that would delay generic Plavix until mid-2011, about six months before its maximum patent life would expire. The settlement provided Apotex with at least $40m.

But such so-called “reverse settlements” that provide compensation to delay cheaper generic medicines have come under scrutiny by US regulators at the Federal Trade Commission.

The settlement Bristol and Sanofi reached with Apotex required FTC approval, and it was amended to help satisfy regulators’ concerns.

However, the settlement negotiations triggered a Department of Justice criminal investigation into allegations that Bristol lied to the government about the terms of the amended deal with Apotex. Apotex had told regulators that Bristol had offered a secret side-deal not to launch its own generic version of Plavix. Bristol denies that.

In the shadow of a criminal investigation, regulators blocked the settlement between Bristol, Sanofi and Apotex.

Nevertheless, certain provisions of the agreement remained in effect. Apotex secured an agreement that the two companies would not seek a temporary restraining order for five business days if it launched generic Plavix and an agreement to cap punitive damages if it lost a patent trial.

That agreement has allowed Apotex to sell as much generic Plavix as possible. Bristol and Sanofi have had to cut their price and have lost market share.

The decision on Thursday is a reprieve for Plavix franchise, but some damage will last because no recall was ordered on product still in the market. Bristol and Sanofi also were ordered to post a $400m bond to pay Apotex in case they lose the patent trial.

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