Federal Circuit Affirms Nonobviousness of Plavix Isomer Patent

Sanofi Synthelabo v. Apotex (Fed. Cir. 2008)

In an opinion by Judge Newman, the Federal Circuit affirmed the validity of Sanofi’s patent covering the blockbuster drug Plavix. The Plavix patent covers a dextrorotatory isomer. The validity question rises from the fact that the racemate of the compound was known and described in earlier Sanofi patents. For its obviousness argument, Apotex noted that separation of enantiomers is routine and that there are many examples of compounds that exhibit stereoselectivity. Thus – Apotex argued – there was both motivation and means for creating the Plavix compound from the known racemate that Sanofi had previously admitted was an important compound.

The Federal Circuit disagreed with Apotex – finding “no error in the district court’s findings that, on the state of the prior art, a person of ordinary skill would not have had the expectation that separating the enantiomers would be likely to produce an isomer having absolute stereoselectivity as to both the favorable antiplatelet activity and the unfavorable neurotoxicity.”


  • This case falls in line with the Federal Circuit’s 2006 decision on preliminary injunction in this case. [Link]
  • In November 2008, the Canadian Supreme Court affirmed patentability of the Canadian patent on Plavix. [Link]