Forest Labs' Lexapro Patent Withstands Teva's Appeal at Federal Circuit

Forest Labs. v. Ivax Pharms. and Cipla, No. 2007-1059 (Fed. Cir. 2007)

In an opinion released today, the Court of Appeals for the Federal Circuit affirmed a district court decision that upheld the validity of Forest Labs' U.S. Reissue Patent 34,712, which covers (+)-citalopram, the active ingredient in Lexapro.  Teva, seeking to market a generic version of Lexapro before the '712 patent expires in 2012, challenged the patent's validity in a paragraph IV filing.

Teva's lead argument (which took up the entire 30-minute oral argument in May) was that the claims of the '712 patent were anticipated by a prior art reference that predicted that one enantiomer of the racemate, citalopram, would be more active than the other.  The Federal Circuit affirmed the district court's conclusion that the prior art reference was not enabled, and therefore not anticipating.

Teva's second argument was that the claims of the '712 patent were obvious in light of racemic citalopram and known techniques of separating enantiomers from their racemates.  The Federal Circuit dismissed this argument in less than a paragraph, stating: " As with their arguments on anticipation, Ivax and Cipla mainly emphasize the evidence that is favorable to their desired outcome without addressing the evidence favorable to Forest."

Forest earns more than $2 billion annually on U.S. sales of Lexapro.  If today's decision sticks, Teva won't be able to sell a generic version until 2013, when Forest's pediatric exclusivity on the drug expires.

RELATED READING:

• Reuters story
• Patent Docs post
• Patently-O: part 1; part 2
• July 16, 2006 OBB post on the district court decision