New York, NY - A bid by generic drug maker Apotex to render invalid the patent on Sanofi-Aventis/Bristol-Myers Squibb's Plavix (clopidogrel) has been rejected.

On June 19, 2007, US District Judge Sidney H Stein upheld the patent. He said Sanofi Aventis was entitled to a permanent injunction to prevent further infringement by Apotex, which had hoped to introduce its own, generic version of the drug.

Apotex actually introduced a generic version of clopidogrel in the US last August, but later that same month Stein ruled that the company could not sell the product until he could hear the patent case.

The trial focused on the validity of a patent on Plavix, which runs until 2011. Apotex argued that the development of Plavix was "obvious" from a prior patent held by Sanofi, so the current patent should be invalid, but the court found that Apotex failed to prove by clear and convincing evidence that the patent was invalid or unenforceable, a Dow Jones news report notes.

The Associated Press reports that Stein said Sanofi had shown it was likely to suffer irreparable price erosion, loss of goodwill, and a negative impact on the amount of research devoted to developing other medical uses for Plavix if sales of the generic version were allowed.

Damages will be determined at a later date.

Plavix is the second-best-selling drug in the world, with sales of more than $6 billon.