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In re Gabapentin Patent Litigation

August 27, 2009

IN RE GABAPENTIN PATENT LITIGATION


The opinion of the court was delivered by: Hon. Faith S. Hochberg, U.S.D.J.

FOR PUBLICATION

MDL Docket No. 1384

This Filing Applies To: Teva Defendants C.A. No. 00-CV-4168 (FSH) C.A. No. 00-CV-4589 (FSH) IVAX Defendants C.A. No. 00-CV-6073 (FSH) C.A. No. 01-CV-0193 (FSH) C.A. No. 01-CV-1537 (FSH) Eon Defendants C.A. No. 01-CV-2194 (FSH)

OPINION

HOCHBERG, District Judge

This matter comes before the Court upon Plaintiff Warner-Lambert's Motion to Strike Certain Affirmative Defenses of the Teva, IVAX, and Eon Defendants (Docket # 430), pursuant to Fed. R. Civ. P. 12(f).*fn1 The Court has considered the briefs of the parties, and oral argument held on April 22, 2009.*fn2

I. Background

Plaintiffs are the drug manufacturers and patent holders for gabapentin, a drug that is used to prevent and limit epileptic seizures. Gabapentin has been marketed under the tradename Neurontin since 1994.*fn3 Defendants are generic drug manufacturers seeking to market their own generic versions of Neurontin.*fn4 Plaintiffs brought suit against Defendants, alleging infringement of U.S. Patent No. 6,054,482, entitled "Lactam-Free Amino Acids" (the "'482 Patent").*fn5 The facts and allegations underlying this action have been discussed comprehensively, both in this Court's earlier opinions and in other actions involving the same parties and patents. However, for purposes of this motion and the others decided by the Court today, the following background is relevant and bears repeating.

A. Warner-Lambert's Gabapentin Patents

Warner-Lambert scientists discovered gabapentin in the 1970s, and learned that gabapentin was useful in preventing and limiting epileptic seizures. Warner-Lambert has since obtained various patents covering the drug and its uses. In 1977, Warner-Lambert obtained U.S. Patent No. 4,024,175 (the "'175 Patent"), which claimed the chemical molecule gabapentin anhydrous. The '175 Patent expired in 1994. In 1979, Warner-Lambert obtained U.S. Patent No. 4,087,544 (the "'544 Patent") covering the use of gabapentin to treat epilepsy. The '544 Patent would have expired on May 2, 1995, but its term was extended under 35 U.S.C. § 156 until January 16, 2000 (and subsequently until July 16, 2000 pursuant to the FDA's pediatric exclusivity regulations).

In the late 1980s, Warner-Lambert chemists discovered a new form of the gabapentin compound in which each gabapentin molecule is associated with one molecule of water.*fn6 This monohydrate is very crystalline and can be purified to a high degree. After purification, the monohydrate can be readily converted back to the anhydrous form, containing no water. On January 16, 1990, Warner-Lambert obtained U.S. Patent No. 4,894,476 (the "'476 Patent") claiming the new monohydrate. The '476 Patent expired on May 2, 2008.

At about the same time, Warner-Lambert also discovered that gabapentin could be useful in slowing or preventing neurodegeneration. On January 28, 1992, Warner-Lambert received U.S. Patent No. 5,084,479 (the "'479 Patent"), claiming the use of gabapentin anhydrous to treat neurodegenerative diseases. This patent expires on January 2, 2010. The '479 Patent's dependent claims describe a method wherein the neurodegenerative disease is stroke, Alzheimer's disease, Huntington's disease, Amyotrophic Lateral Sclerosis (A.L.S.), and Parkinson's disease. Warner-Lambert has neither sought nor received FDA approval to promote Neurontin for the treatment of neurodegenerative diseases.

Despite holding the initial patent for gabapentin since 1979, the creation of a commercially viable gabapentin product was complicated by the fact that under certain conditions during the manufacturing process, gabapentin has a tendency to form a lactam, which makes the drug unstable and unsafe. Warner-Lambert scientists ultimately determined that all gabapentin products had to be essentially free from mineral acid impurities, and that certain adjuvants that promote the conversion of gabapentin to gabapentin lactam must be avoided. In an effort to minimize the formation of lactam during the manufacturing process, Warner Lambert developed a new process, for which the company sought an additional patent in August 1990 when it filed U.S. Patent Application No. 07/570,500 ("the '500 Application"). As described below, the parties dispute the details of the resulting patent prosecution. The low-lactam gabapentin patent ultimately issued as the '482 Patent on April 25, 2000 and it expires on April 25, 2017. The '482 Patent is the subject of Warner-Lambert's current infringement actions.*fn7

B. Neurontin And The Neurontin Market

Warner-Lambert developed its Neurontin products on the basis of these patents. Following clinical trials, Warner-Lambert submitted New Drug Applications ("NDAs") to the FDA for the use of gabapentin to treat epilepsy. The FDA approved NDA No. 20-235, for Neurontin capsules, on December 30, 1993 and NDA No. 20-882, for Neurontin tablets, on October 9, 1998.

Warner-Lambert filed several Orange Book listings in connection with the development and sale of Neurontin. In January 1992, Warner-Lambert certified that the '175 Patent and the '544 Patent covered the formulation, composition and/or method of use of the drug product that was the subject of NDA No. 20-235. Both the '175 Patent and the '544 Patent were then listed in the Orange Book. Once NDA No. 20-235 was approved, Warner-Lambert amended its patent notification statement to include the '476 and '479 Patents, certifying that they also covered the formulation, composition and/or method of use of the drug product that was the subject of that NDA. They were listed in the Orange Book in May 1994 and January 1996, respectively. In April 2000, Warner-Lambert certified that the '482 Patent also covered the drug product at issue in both NDA No. 20-235 and NDA No. 20-882, resulting in an Orange Book listing for the '482 Patent as well.

Warner-Lambert first began selling Neurontin capsules in early 1994. According to the FDA's required labeling, gabapentin is useful for "adjunctive therapy in the treatment of partial seizures with and without secondary generalization in adults with ...


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