A U.S. appeals court ruled in favor of Bristol-Myers and Sanofi-Aventis to prevent generic competition to the blood-thinner Plavix (Clopidrogel) the world’s best selling drug, in the U.S. until 2011.

Canadian drugmaker Apotex did not convince the jurors that the Plavix patent is not a new invention and that the Sanofi’s scientist used known research methods on known compounds to come up with Plavix’s key ingredient.

Plavix had revenues of $4.13 billion dollars for the first nine months and Sanofi-Aventis was its second best drug (only to blood thinner Lovenox) with revenues of $2.99 billion dollars, for a total of $7.12 billion in global sales for the January-September 2008 period.

Bristol-Myers Squibb is seeking economic compensation of sales lost over the brief but notorious launch of Apotex clopidogrel shipped in August 2006 and that costed Bristol (according to the New York-based company) between $1.45 and $1.75 billion dollars. By a previous agreement of the three companies involved, however, Bristol or Sanofi can’t ask for compensation of more than 70 percent of net lost sales and waived their right to ask the judge to triple the damages because of willful infringement.

Apotex informed that they will appeal the court to reconsider the case.