Judges: Lourie (author), Linn, Moore

[Appealed from D.N.J., Judge Lifland]

In In re Gabapentin Patent Litigation, No. 06- 1572 (Fed. Cir. Sept. 21, 2007), the Federal Circuit reversed the district court’s grant of SJ of noninfringement, affirmed the district court’s claim construction of disputed terms, and remanded the case for reconsideration of infringement in accordance with the opinion.

Warner Lambert Co., Pfizer Inc., and Gödecke Aktiengesellschaft (collectively “Warner Lambert”) manufacture and sell Neurontin®, a drug for treating brain disorders, including epilepsy. The active ingredient in Neurontin® is gabapentin, a compound covered by U.S. Patent No. 6,054,482 (“the ’482 patent”). The ’482 patent covers a process for preparing gabapentin while minimizing the formation of a lactam, which can make the drug unstable and unsafe. This process has two key limitations: (1) the gabapentin must be highly purified before being formulated into a pharmaceutical, and thus may not contain more than 20 parts per million (“ppm”) of an anion of a mineral acid; and (2) certain adjuvants that reduce the stability of gabapentin must be avoided.

A number of generic drug companies filed ANDAs seeking approval to market generic versions of Neurontin®. Each of these companies committed to using a version of gabapentin manufactured by Teva Pharmaceutical Industries, Ltd. and Teva Pharmaceuticals USA, Inc. (collectively “Teva”). Warner Lambert filed suit against several of these companies pursuant to the Hatch-Waxman Act, including Purepac Pharmaceutical Co., Watson Pharmaceuticals, Inc., Teva, IVAX Corp., Apotex Corp., and Eon Labs Manufacturing, Inc. (collectively “appellees”). These lawsuits were consolidated for pretrial proceedings in the U.S. District Court for the District of New Jersey. The district court construed three claim terms— “anion of a mineral acid,” “adjuvant,” and “modified maize starch”—and granted appellees’ motion for SJ of noninfringement based on Warner Lambert’s failure to meet its burden of proof of infringement of the ’482 patent claims.

In the SJ proceedings in the district court, the parties had presented conflicting expert opinions and testing data regarding whether Teva’s gabapentin product infringed the ’482 patent claims. At issue was whether the accused product contained “less than 20 ppm of an anion of a mineral acid,” as required by the asserted claims. The district court held that Warner Lambert’s pH-based tests were insufficiently precise to prove infringement, and therefore held that Warner Lambert had failed to meet its burden of proof. The Federal Circuit reviewed the district court’s grant of SJ de novo, drawing all justifiable inferences in favor of Warner Lambert, the nonmovant. In doing so, the Federal Circuit analyzed the testing data provided by Warner Lambert’s expert and determined that Warner Lambert had provided sufficient evidence to create a genuine issue of material fact regarding whether Teva’s samples met the limitations of the claims of the ’482 patent.

The Federal Circuit also held that Warner Lambert’s comparative testing was sufficient evidence of infringement, and that there was no requirement for quantitative testing, distinguishing the facts from those of Abbott Laboratories v. TorPharm, Inc., 300 F.3d 1367 (Fed. Cir. 2002), and Zenith Laboratories, Inc. v. Bristol-Myers Squibb Co., 19 F.3d 1418 (Fed. Cir. 1994). In Abbott and Zenith, the Court held that quantitative testing was necessary where the proffered testing failed to provide the requisite proof. Abbott, 300 F.3d at 1376-77; Zenith, 19 F.3d at 1423. The Federal Circuit noted that here, it would not consider appellees’ arguments regarding the accuracy of Warner Lambert’s testing techniques because appellees had waived these arguments in their motion for SJ to the district court.

Regarding claim construction, the Federal Circuit affirmed the district court’s construction of the terms “anion of a mineral acid,” “adjuvant,” and “modified maize starch.” The Court held that the proper construction of the term “anion of a mineral acid” is an “anion derived from a mineral acid,” stating that this construction was supported by the plain language of the claim and the specification and, thus, there was no need to rely on the prosecution history “where the claim language provides a clear definition of the disputed claim term, supported by the specification.” Slip op. at 15.

With regard to the term “adjuvant,” the Federal Circuit first held that construction of the term was properly before the court because the district court had entered final judgment on the court’s claim construction rulings by granting certification to the Federal Circuit under Rule 54(b). The Federal Circuit then affirmed that the correct construction of the term “adjuvant” excluded ingredients located in the capsule shell or tablet coating, finding support for this construction in the claim language itself, particularly in view of the lack of contradictory statements in the specification and prosecution history.

Finally, the Federal Circuit rejected appellees’ assertion that the district court erred in construing “modified maize starch” as “maize starch modified by acid treatment.” The Court held that the specification supported a conclusion that “modified maize starch” does not encompass pregelatinized starch and that this was supported by an expert declaration in the prosecution history.