It was a good day for Sanofi-Aventis and Bristol-Myers Squibb yesterday after a US judge ruled that Canadian group Apotex should pay damages of $442.2 million (plus interest) for violating patents protecting the blockbuster Plavix.

The saga dates back to 2006 when the Toronto, Canada-based firm flooded the market with copycat versions of the multi-billion-dollar bloodthinner Plavix (clopidogrel), currently the world’s second-biggest selling drug, for a three-week period while its patent protection was still in force.

A heated and lengthy court battle saw Apotex fight with Sanofi and B-MS over the validity of Plavix’ patents but, in 2007, a court ruled against the Canadian group by declaring that the drug’s protection - actually due to come to an end next year - is enforceable.

One of the last aspects of this complex case was the amount of damages due to Sanofi and B-MS, and the matter may now finally be laid to rest after New York Judge Sidney Stein agreed that Apotex should cough up half of the $884.4 million in net sales it made from selling generic Plavix during its brief stint on the market.

Judge Stein threw out Apotex’ claims that it should only pay 40% of net sales it made because the French drugmaker had marketed an authorised generic form of Plavix, concluding that Sanofi had actually only cut the cost of its brand rather than launch a separate copycat product, according to media reports.