Finding no error in the district court’s holding that the reverse doctrine of equivalents was inapplicable and that claim preclusion prohibited the defendant from raising other validity challenges, the U.S. Court of Appeals for the Federal Circuit affirmed a district court’s finding of patent validity and infringement. Roche Palo Alto, LLC v. Apotex, Inc., Case No. 08-1021 (Fed. Cir., July 9, 2008) (Prost, J.).

Acular® and Acular®LS are marketed by Roche Palo Alto, LLC (Roche) for the treatment of eye inflammation. Roche’s patent covering these drug formulations claims a non-steroidal anti-inflammatory drug (NSAID), a quaternary ammonium preservative and the nonionic surfactant octoxynol 40 (O40). The claims were allowed following Roche’s argument that the inclusion of O40 produced the unexpected result of a clear solution.

Apotex filed two Abbreviated New Drug Applications (ANDAs) directed to generic versions of Acular® (ANDA-1) and Acular® (ANDA-2). The concentration of O40 was reduced in the ANDA-2 formulation, but both formulations were within the claimed range of ingredients. Apotex was found to infringe and the patent was held valid during the ANDA-1 litigation. Roche sued based on the ANDA-2 formulation. Apotex asserted the defense of non-infringement under the reverse doctrine of equivalents and further argued that its invalidity arguments should not be barred under the doctrine of claim preclusion.

The Federal Circuit affirmed the lower court’s finding that the defendant failed to establish a prima facie case of non-infringement. Under the reverse doctrine of equivalents, an accused product falling within the literal scope of the claims can be found to not infringe where it is so far changed in principle such that it performs the same or similar function in a substantially different way. Apotex argued that its lower concentration of O40 changed the principle of the ANDA-2 formulation to provide stability in a substantially different way compared to the claimed formulation. The Court declined to consider this argument because Apotex relied exclusively on its expert witness instead of properly determining the principle of the invention from the specification, prosecution history and prior art. The Federal Circuit added that the reverse doctrine of equivalents is rarely applied (and that it has never affirmed a finding of non-infringement under the doctrine).

The Federal Circuit further agreed with the district court that Apotex’s invalidity claims were precluded by earlier litigation. The accused products in both the ANDA-1 and ANDA-2 litigations were encompassed by the claims of the patent, constituting the “same claim” for purposes of claim preclusion. Apotex also argued that, because of KSR, there should be a “change of law” exception to claim preclusion. The Federal Circuit disagreed, stating that although there may be rare exceptions in cases involving “momentous changes in important, fundamental constitutional rights,” KSR involved no such rights.