By Donald Zuhn --
Last Friday, the Federal Circuit reversed a District Court's finding on summary judgment that eight generic drug manufacturers did not infringe U.S. Patent No. 6,054,482 (the '482 patent), and affirmed the District Court's construction of two disputed claim limitations.
Plaintiffs-Appellants Warner Lambert Co., Pfizer Inc., and Gödecke Aktiengesellschaft (Warner Lambert) manufacture and sell Neurontin®, which is used to treat cerebral disorders such as epilepsy and which comprises the active ingredient gabapentin. Warner Lambert discovered that under certain manufacturing conditions, gabapentin can form a lactam. To minimize the formation of the lactam, which is twenty-five times more toxic than gabapentin and which causes - rather than prevents - seizures, Warner Lambert developed a process for preparing stable and safe gabapentin formulations. The '482 patent is directed towards this process as well as to gabapentin compositions that are substantially free from a lactam contaminant.
Seeking approval to market generic gabapentin, Defendants-Appellees Purepac Pharmaceutical Co., Faulding Inc., Teva Pharmaceutical Industries, Inc., Teva Pharmaceuticals USA, Inc., Zenith Laboratories, Inc. (now IVAX Pharmaceuticals NV, Inc.), Zenith Goldline Pharmaceuticals, Inc. (now IVAX Pharmaceuticals, Inc), IVAX Corp., and Eon Labs Manufacturing, Inc. (Appellees) filed Abbreviated New 
Drug Applications (ANDAs) with the FDA. In response, Warner Lambert brought number of infringement actions against the Appellees; the suits were consolidated in the District Court of New Jersey.
In pretrial proceedings, the Appellees moved for summary judgment of noninfringement and invalidity of the '482 patent. The District Court granted Appellees' motion for summary judgment of noninfringement, determining that Warner Lambert had failed to establish that the accused products contained no more than 20 parts per million (ppm) of anions of mineral acid as required by the asserted claims (more anions of mineral acid indicates the presence of gabapentin hydrochloride - the salt form of gabapentin, which in turn indicates that the gabapentin sample is less pure, and therefore, less stable; less stable formulations of gabapentin contain lactam contaminant). In addition, the District Court construed two claim terms in Warner Lambert's favor. In particular, the District Court construed the term "anion of a mineral acid" as an "anion derived from a mineral acid" and the term "adjuvant" as a "subset of [eight particular] inactive ingredients that is intimately mixed with gabapentin to form the drug mixture, and thus [does not] refer to the ingredients of capsule shells or tablet coatings."
On appeal, Warner Lambert argued that the District Court, in granting summary judgment of noninfringement, erred by resolving factual disputes. In opposing the Appellees' motion for summary judgment, Warner Lambert had submitted the results of a comparative pH test that established that four of five of the Appellees' samples tested contained not more than 17 ppm of anions of mineral acid. In response, the Appellees challenged the accuracy and reliability of Warner Lambert's comparative pH test.
The Federal Circuit, however, noted that the Appellees had "waived any argument challenging the validity, including challenges to the accuracy or reliability, of the pH testing method for purposes of summary judgment," and were therefore confined to arguing against "the undisputed limits of the test's precision" (i.e., a ± 5 ppm margin of error). When so confined, the CAFC concluded that the Appellees could not counter Warner Lambert's demonstration that the Appellees' gabapentin (at left) samples contained less than 20 ppm of anions of a mineral acid, as recited in the claims. Thus, the Federal Circuit concluded that "the district court erred in granting summary judgment of noninfringement based on Warner Lambert's purported failure to meet its burden of proof" since "[t]he record shows that Warner Lambert proffered sufficient evidence to create a genuine issue of material fact regarding whether the accused products met the 20 ppm claim limitation of the '482 patent."
With respect to the District Court's construction of the term "anion of a mineral acid," the Appellees argued that the term refers to total chloride content and is not limited to acid-derived chloride ions. The Appellees also argued that the term "adjuvant" refers to any ingredient other than the active ingredient, and thus encompasses ingredients included in the capsule shell or tablet coating.
In affirming the District Court's construction of the first disputed claim term, the Federal Circuit determined that "the construction adopted by the district court gives full meaning to every word of the entire claim term," and that "[h]ad the patentees intended the anion to refer to any anion, regardless of its source, the patentees could have simply claimed 'anions' and omitted the phrase 'of a mineral acid.'" With respect to the second disputed claim term, the CAFC noted that the District Court had "found nothing in the patent or prosecution history indicating that ingredients found in the capsule shell or coating affects stability, and also relied on several dictionary definitions in support of its construction." As a result, the Federal Circuit concluded that the District Court also did not err in construing the term "adjuvant."
In re Gabapentin Patent Litigation (Fed. Cir. 2007)
Panel: Circuit Judges Lourie, Lyn, and Moore
Opinion by Circuit Judge LourieAdditional information regarding this case can be found at the Orange Book Blog and Patently-O.
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