ENANTIOMERS ARE NOT NECESSARILY OBVIOUS

Sanofi-Synthelabo v. Apotex, Inc., [2007-1438] (December 12, 2008) [NEWMAN, Lourie, Bryson] The Federal Circuit affirmed the district court’s ruling sustaining validity of U.S. Patent No. 4,847,265 on Plavix®.
DISCUSSION: The Federal Circuited noted that it has recognized the known difficulty of separating enantiomers and the unpredictability of their properties, and held that a reference that stated that a compound has enantiomers did not enable the separation of those enantiomers, where the reference did not teach how to obtain the enantiomer. The Federal Circuit found no clear error in the district court’s finding herein that the reference patents would not have enabled a person of ordinary skill to obtain clopidogrel substantially separated from the levorotatory enantiomer, and affirmed the finding of validity. As to obviousness, the Federal Circuit noted obviousness cannot be avoided simply by a showing of some degree of unpredictability in the art so long as there was a reasonable probability of success.” However, the Federal Circuit noted that on the basis of the trial evidence, the district court found that a person of ordinary skill in this field would not reasonably have predicted that the dextrorotatory enantiomer would provide all of the antiplatelet activity and none of the adverse neurotoxicity. Clear error has not been shown in this finding, and in the conclusion of nonobviousness based thereon. The difficulties in separating the enantiomers also contributed to the non-obviousness.