U.S. District Court Decision about Eisai's Legal Action over Aricept ODT® ANDA Filing

Eisai Co., Ltd.
Eisai Inc.

Tokyo, Japan and Woodcliff Lake, NJ, December 27, 2007 --- Eisai Co., Ltd. (Headquarters: Tokyo, President and CEO: Haruo Naito) and Eisai Inc. (Headquarters: New Jersey, Chairman and CEO: Hajime Shimizu) (collectively “Eisai”) filed a lawsuit in August 2006 against Mutual Pharmaceutical Co., Inc. and United Research Laboratories, Inc. (collectively “Mutual”) claiming that its submission of an abbreviated new drug application (ANDA) to the U.S. Food and Drug Administration (FDA) for Aricept ODT® (donepezil hydrochloride orally disintegrating tablets) would infringe Eisai's composition of matter patent.

On December 20, 2007 (U.S. EST), the U.S. District Court for the District of New Jersey issued a ruling dismissing the lawsuit against Mutual on the procedural grounds that there is no case or controversy between the parties, because Mutual did not make a certification challenging the patent and does not yet have FDA approval to market its product. The Court recognized that Mutual is required, by a stipulation entered between the parties and signed by the Court, to give Eisai 45 days' notice of any launch of a generic version of Aricept ODT®, and Eisai may during that 45-day period bring an action against Mutual for patent infringement and seek injunctive relief against Mutual's sales of any such product. Therefore, Mutual cannot market the generic version of Aricept ODT® immediately.

The Court did not address the substantive merits of Eisai's infringement action against Mutual. Eisai believes that its donepezil composition of matter patent is valid and enforceable until its expiration date of November 25, 2010, and that Mutual would clearly infringe its donepezil composition of matter patent if Mutual were to launch a generic version of Aricept ODT® in the United States prior to the expiration. Eisai intends to vigorously enforce and defend that patent.

The Court's ruling has no impact on Eisai's ongoing infringement action against Teva Pharmaceuticals for its ANDA for generic Aricept® (donepezil hydrochloride).

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