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Foreseeable Equivalent Cannot Be Reached by DOE

January 29, 2004

Decision icon Decision

Last Month at the Federal Circuit - February 2004

Judges: Rader (author), Gajarsa, and Plager

The Federal Circuit also considered the ‘798 patent and estoppel issues in Glaxo Wellcome, Inc. v. Impax Laboratories, Inc., No. 03-1013 (Fed. Cir. Jan. 29, 2004). In Glaxo, the Federal Circuit affirmed the district court’s determination on SJ that Impax Laboratories, Inc. (“Impax”) could not infringe the asserted claims under the DOE.

Impax, a manufacturer of generic pharmaceuticals, filed two ANDAs with the FDA, one for a generic version of Wellbutrin®SR, and the other for a generic version of Zyban®. In both ANDAs, Impax made a paragraph IV certification that its generic sustained-release bupropion hydrochloride tablets do not infringe Glaxo’s ‘798 patent. The sustained-release agent in Impax’s proposed composition is hydroxypropyl cellulose (HPC). Upon receiving notice of Impax’s ANDA filings, Glaxo filed suit against Impax alleging infringement of the ‘798 patent.

Arguing prosecution history estoppel, Impax moved for SJ of noninfringement. The trial court granted Impax’s motion, noting in the process that the claim amendments indisputably narrowed the patent with respect to sustained release.

On appeal, Glaxo argued that the district court had erred in granting SJ because HPC is equivalent to HPMC. Glaxo further contended that it had not surrendered HPMC equivalents during prosecution of the ‘798 patent.

As it did in the SmithKline decision discussed above, the Federal Circuit found that Glaxo had narrowed the claims during prosecution and, in so doing, had presumptively surrendered the territory that embraced Impax’s sustained-release agent. During prosecution, the Examiner had rejected the claims for lack of enablement. The Examiner considered the recitation of HPMC, the only disclosed sustained-release mechanism, “critical” for the controlled or sustained-release aspect of the claims. The Examiner also noted that the application’s disclosure of a single species, HPMC, did not support claims to a generic concept. To overcome that rejection, Glaxo amended the claims to define HPMC.

Glaxo argued that because it could not have added HPC to its claims at the time of the amendment without drawing a new matter rejection, the presumption of claim surrender should not apply. The Federal Circuit rejected this argument, noting that the quintessential example of an enforceable equivalent—after-arising technology—would always be unclaimable new matter.

Contrary to the evidence in the SmithKline case concerning the foreseeability of PVA, the evidence in this case suggested that HPC was a foreseeable time-release agent at the time of filing and amendment. Accordingly, the Court found that Glaxo had not rebutted the presumption that prosecution history estoppel bars a finding of infringement under the DOE.

Not all of the claims were amended during prosecution. Rather, claim 1 originally recited HPMC as the sustained-release agent for bupropion. Because Glaxo did not amend this claim during prosecution, it argued that the presumption of claim surrender did not operate to divest that claim of its equivalents armor. The Federal Circuit ruled against Glaxo, however, based on the concept of “infectious estoppel.” To find otherwise, the Court concluded, would create inconsistency within the patent.