Alzheimer’s Drug Patent Ruling Affects Amneal’s Exclusivity Suit

By Dana A. Elfin

Allergan Inc. subsidiary Forest Laboratories, the maker of the Alzheimer’s treatment Namenda XR, lost its bid to overturn a district court ruling finding its patents on the drug invalid.

In a nonprecedential Dec. 11 ruling, the U.S. Court of Appeals for the Federal Circuit affirmed a trial court decision in favor of Teva Pharmaceuticals USA Inc. The decision could affect Amneal Pharmaceuticals’ suit against the FDA over exclusivity rights for generic Namenda XR and the ability of generic Namenda XR applicants to enter the market.

Amneal was the first to file an abbreviated new drug application (ANDA) challenging the patents on the Namenda XR drug and qualified for the valuable 180 days of market exclusivity on the generic version. Amneal’s case, which is before the U.S. District Court for the District of Columbia, challenges the Food and Drug Administration over its decision to strip Amneal of its exclusivity rights.

Generic Entry Could Be Affected

The FDA said Amneal forfeited its exclusivity because it didn’t obtain tentative approval of its generic within 30 months of filing its application.

Following the Federal Circuit’s invalidity ruling on Forest’s Namenda XR patents, Amneal asked the D.C. district court for an expedited hearing on the parties’ pending motions for summary judgment in the exclusivity case.

“ANDA applicants approved by FDA are unable to market their approved generic versions of Namenda XR due to patent and/or contractual rights held by Forest Laboratories, the [new drug application] holder,” Amneal told the district court. “The issuance of a Federal Circuit mandate affirming the invalidation of those patents will remove those bars to competing generic entry.”

Unless Forest petitions the Federal Circuit for a panel rehearing or a rehearing by the full court, the patent invalidity decision will become final Jan. 17, 2018. Amneal wants the district court to decide the issues in the exclusivity case against the FDA before that date.

Claims Found Indefinite

Like Amneal, Teva submitted an abbreviated new drug application to make a generic version of Namenda XR (memantine hydrochloride extended release) in 2013 and claimed the patents were invalid or its generic wouldn’t infringe the patents. Subsequently, Forest and Adamas Pharmaceuticals Inc.—from which Forest licenses patents—sued Teva for patent infringement in the U.S. District Court for the District of Delaware.

In 2016, the Delaware district court ruled in Teva’s favor after finding the drug patents invalid for indefiniteness. Forest exclusively licenses the composition and method patents from Adamas Pharmaceuticals.

Patents are invalid for indefiniteness if their claims, read in light of the patent specification and the patent’s prosecution history, don’t inform with reasonable certainty those skilled in the art about the invention’s scope.

Forest appealed to the Federal Circuit but had no better luck there.

Forest Interpretation Unreasonable

Forest’s reading of the claim was unreasonable and didn’t make sense in the context of the internal evidence related to the patent, the Federal Circuit said.

“The descriptions of the figures are no more than what they purport to be: descriptions of the figures,” the opinion said. “They do not constitute a definition and are not even directed to the meaning of the claim terms.”

Nor did the patent’s prosecution history provide support for Forest’s proposed claim construction, the appeals court said. It also rejected Forest’s attempts to raise a new construction of the claim on appeal, finding Forest had waived the argument because it had earlier asked the district court to reject that same construction.

Bloomberg Law contacted Forest for comment on the decision but no one was available to respond. Teva is pleased with the decision, Teva spokeswoman Elizabeth DeLuca told Bloomberg Law. Meanwhile, Teva has entered into a confidential settlement with Forest over its Namenda XR application, she said. According to information on the FDA’s website, Teva still needs to get the agency’s final approval on the product.

To date, the FDA has granted final approval for several generic versions of Namenda XR, including those from Lupin Ltd., Mylan Pharmaceuticals Inc. and Sun Pharma Global FZE. Forest’s settlements with the various manufacturers provide for generic entry in January 2020.

Judge Richard G. Taranto wrote the Federal Circuit’s opinion. Judge Alan D. Lourie filed a concurring opinion. Judge Jimmie V. Reyna also heard oral argument in the case.

Covington & Burling LLP and Quinn Emanuel Uquhart & Sullivan LLP represented Forest. Forest, based in New York, is owned by Allergan Inc., based in ireland.

Carlson Caspers Vandenburgh Lindquist & Schuman PA represented Teva Pharmaceuticals USA, based in North Wales, Pa. Parent company Teva Pharmaceuticals Ltd. is based in Israel.

The case is Forest Labs., Inc. v. Teva Pharm. USA, Inc. , Fed. Cir., 2016-2550, 2016-2553, nonprecedential 12/11/17 .

To contact the reporter on this story: Dana A. Elfin in Washington at

To contact the editor responsible for this story: Brian Broderick at

For More Information

The ruling is at

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