Date: 09-21-2007

Case Style: IN RE GABAPENTIN PATENT LITIGATION

Case Number: 2006-1572

Judge: Louiri

Court: United States Court of Appeals for the Federal Circuit on appeal from the District of New Jersey (Essex County)

Plaintiff's Attorney:

Jack B. Blumenfeld, Morris, Nichols, Arsht & Tunnell LLP, of Wilmington, Delaware, argued for plaintiffs-appellants. With him on the brief were Karen Jacobs Louden, Benjamin Schladweiler, and Richard J. Bauer.

Defendant's Attorney:

Edgar H. Haug, Frommer Lawrence & Haug LLP, of New York, New York, argued for defendants-appellees, Purepac Pharmaceutical Co. and Faulding, Inc. With him on the brief were Steven M. Amundson and Andrew S. Chalson.

Steven J. Lee, Kenyon & Kenyon LLP, of New York, New York, argued for defendants-appellees, Teva Pharmaceutical Industries, Ltd., et al. With him on the brief was Elizabeth Holland. Of counsel were William G. James, II and Patrice P. Jean of Washington, DC.

Richard J. Basile, St. Onge Steward Johnston & Reens LLC, of Stamford, Connecticut, for defendant-appellee, Eon Labs Manufacturing, Inc. With him on the brief were Stephen P. McMamara and Stanley H. Lieberstein. Of counsel were James P. Jeffry and Benjamin J. Lehberger.

Description:

Warner Lambert Co., Pfizer Inc., and Gödecke Aktiengesellschaft (collectively "Warner Lambert") appeal from the judgment of the United States District Court for the District of New Jersey granting summary judgment of noninfringement of claims 7-11 of U.S. Patent 6,054,482 ("the '482 patent") in favor of appellees Purepac Pharmaceutical Co., Faulding Inc., Teva Pharmaceutical Industries, Inc., Teva Pharmaceuticals USA, Inc. (collectively "Teva"), Zenith Laboratories, Inc. (now known as IVAX Pharmaceuticals NV, Inc.), Zenith Goldline Pharmaceuticals, Inc. (now known as IVAX Pharmaceuticals, Inc), IVAX Corp. (collectively "IVAX"), and Eon Labs Manufacturing, Inc. (generic defendants collectively referred to as "appellees"). Because we conclude that the district court erred in determining that there were no genuine issues of material fact concerning whether Warner Lambert failed to meet its burden of proof that the accused products infringe the asserted claims of the '482 patent, we reverse and remand. Because we conclude that the district court did not err in construing the disputed claim limitations, we affirm those aspects of the district court's decision.

BACKGROUND

Warner Lambert manufactures and sells Neurontin®, a drug used to treat certain cerebral disorders, including epilepsy. The active ingredient in Neurontin® is a compound called gabapentin, which is covered by Warner Lambert's '482 patent. That patent, entitled "Lactam-Free Amino Acids," is directed towards a process for the preparation of, and compositions containing, gabapentin substantially free from a lactam contaminant. '482 patent col.2 ll.27-29.

Warner Lambert scientists discovered that under certain conditions gabapentin has a tendency to form a lactam, which makes the drug unstable and unsafe. The lactam was shown to be twenty-five times more toxic than gabapentin, and is linked to causing seizures, rather than preventing them. In re Gabapentin Patent Litig., 393 F. Supp. 2d 278, 280 (D.N.J. 2005). In an effort to minimize the formation of lactam during the manufacturing process, Warner Lambert developed a process disclosed and claimed in the '482 patent. Warner Lambert determined that two limitations must be observed in the process in order to achieve stable formations of gabapentin.

First, the '482 patent discloses that gabapentin must be highly purified before being formulated into the pharmaceutical preparation. While drug manufacturers generally prefer to use salt forms of an active ingredient over the free base form because salts "usually provide good stability and good solubility," '482 patent col.3 ll.61-65, Warner Lambert determined that gabapentin hydrochloride was less stable than free gabapentin. Id. col.3 ll.65-67. Thus, Warner Lambert sought to keep lactam formation to a minimum by preparing gabapentin in its highly purified form. The '482 patent discloses that:

The active materials of formula (I) must be prepared as highly purified, nonderivatized free amino acids, for example, from the corresponding hydrochloride by ion exchange. The proportion of remaining hydrochloride admixtures should thereby not exceed 20 ppm. The same also applies to other mineral acids.

Id. col.5 ll.24-29. Thus, the patent teaches that in preparing purified gabapentin, the hydrochloride admixture, or other mineral acid, remaining from the manufacturing process should not exceed twenty parts per million ("20 ppm").

Second, Warner Lambert determined that certain adjuvants that reduce the stability of gabapentin must be avoided. The '482 patent further discloses that:

The following adjuvant materials, for example, reduced the stability of the compounds (I) and should be avoided in the preparation of pharmaceutical compositions: modified maize starch, sodium croscarmelose, glycerol behenic acid ester, methacrylic acid co-polymers (types A and C), anion exchangers titanium dioxide, and silica gels such as Aerosil 200.

Id. col.5 ll.5-10.

Pursuant to the Hatch-Waxman Act, Warner Lambert filed suit against several generic drug companies that filed Abbreviated New Drug Applications ("ANDAs") with the Food and Drug Administration.1 Those companies sought approval to market generic versions of Neurontin®. In their ANDAs, appellees committed to using Teva's gabapentin active pharmaceutical ingredient in their products. Gabapentin, 393 F. Supp. 2d at 283. Under the direction of the Judicial Panel on Multidistrict Litigation, the actions were consolidated for pretrial proceedings in the United States District Court for the District of New Jersey. Between 2001 and 2003, appellees filed various summary judgment motions, including motions for summary judgment of noninfringement and invalidity. During the pendency of those motions, Warner Lambert sought a preliminary injunction to enjoin IVAX, Purepac, and Teva from launching their products. Those motions were denied.

On August 25, 2005, the district court issued several rulings on the summary judgment motions. The court construed numerous claim terms. At issue in this appeal are two of those terms, namely, "anion of a mineral acid" and "adjuvant." Those terms appear in representative claim 7, which has been asserted against appellees. It claims:

7. A stable and pure pharmaceutical composition in unit dry medicinal dosage form consisting essentially of:

(i) an active ingredient which is gabapentin in the free amino acid, crystalline anhydrous form containing less than 0.5% by weight of its corresponding lactam and less than 20 ppm of an anion of a mineral acid and

(ii) one or more pharmaceutically acceptable adjuvants that do not promote conversion of more than 0.2% by weight of the gabapentin to its corresponding lactam form when stored at 25ºC and an atmospheric humidity of 50% for one year.

'482 patent claim 7 (emphases added). Based on the intrinsic evidence, the court construed "anion of a mineral acid" as an "anion derived from a mineral acid." In re Gabapentin Patent Litig., 395 F. Supp. 2d 153, 163 (D.N.J. 2005). The court further construed "adjuvants" 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." In re Gabapentin Patent Litig., 395 F. Supp. 2d 140, 152 (D.N.J. 2005).

The district court granted appellees' motion for summary judgment of noninfringement based on Warner Lambert's failure to meet its burden of proof. The court determined that Warner Lambert failed to adduce sufficient evidence to establish that the accused products meet the limitation that the anions of a mineral acid do not exceed 20 ppm ("the 20 ppm limitation"). In opposing the motion for summary judgment, Warner Lambert submitted results from a comparative pH test performed by its analytical expert. Warner Lambert argued that those results created a genuine issue of material fact regarding whether the accused products met the 20 ppm limitation.

Based on the undisputed fact that the test had a ± 5 ppm margin of error, the court determined that that evidence was insufficiently precise to prove infringement, and thus granted summary judgment in favor of appellees.

On July 13, 2006, the court entered judgment of noninfringement based on the burden of proof motion in favor of appellees, pursuant to Federal Rule of Civil Procedure 54(b). Warner Lambert timely appealed. We have jurisdiction pursuant to 28 U.S.C. § 1295(a)(1).

* * *

Outcome: For the foregoing reasons, we reverse the district court’s grant of summary judgment of noninfringement, affirm the court’s claim construction of the “anion of a mineral acid” and adjuvant claim limitations, and remand for further proceedings consistent with this opinion.

Plaintiff's Experts: Unknown

Defendant's Experts: Unknown

Comments: None