Obviousness Established Through Routine Testing

In Pfizer, Inc. v. Apotex, Inc., (No. 06-1261; March 22, 2007), a Federal Circuit panel holds Pfizer’s patent to Norvasc (amlodipine besylate) invalid. The validity analysis focuses on whether claims to the drug Norvasc, an acid addition salt of amlodipine and benzene sulphonate, are invalid as obvious. The decision begins by explaining that the lower court improperly relied on the U.S. Patent and Trademark Office examiner’s finding of prima facie obviousness because a court is not bound by an examiner’s findings during ex parte patent application proceedings.

Pfizer argued that the combination of amlodipine and benzene sulphonate was not obvious because the results for such a combination were not predictable. The Federal Circuit panel says, however, that the standard is not whether results are predictable, but instead whether a person having ordinary skill in the art would have a reasonable expectation of success. The panel also reasons that such a person, faced with finding a suitable amlodipine salt, would have narrowed the group of salt forming anions to 53 possibilities. Given this limited number of possibilities that skilled person would have had a reasonable expectation of success in arriving at amlodipine besylate through routine testing.

Pfizer’s offering of secondary considerations is also rejected. In particular, the lower court’s reliance on Pfizer’s decision to switch its commercial drug to amlodipine besylate as a secondary consideration of nonobviousness as well as Pfizer’s offering of unexpected superior results is deemed to be error. The panel finds the evidence that the results were unexpected to be inadequate and that, instead, a skilled person would have expected to discover the result through routine testing. An alternative holding is offered, namely that even if Pfizer showed unexpected superiority for amlodipine besylate, this secondary consideration does not overcome the strong showing of obviousness.