Eisai announced that the United States District Court of NewJersey has ruled in Eisai's favor with respect to Eisai's motion for a preliminary injunction in its patent infringement lawsuit against TevaPharmaceuticals and its division Gate Pharmaceuticals concerning Aricept tablets (Donepezil ). Eisai filed the infringement actions in December 2005 contesting Teva's submission of an abbreviated new drug application (ANDA) to the USFDA for Aricept(R). Teva received tentative approval from the FDA in January, and could receive final approval April 26, following a delay required under federal drug law because of the patent litigation.
Following patents are listed In the Orange book for 5 and 10 mg tablets of Donepezil
US4895841 (Expiry: NOV 25,2010)- Product patent
US5985864 (Expiry: DEC 30,2016)- Polymorph (Form-II, III, IV and V)
US6140321 (Expiry: DEC 30,2016)-polymorph
US6245911 (Expiry: DEC 01,2018)-Polymorph A, B and C
US6372760 (Expiry: MAR 31,2019)- Formulation
Teva alleged earlier that 841’ patent is unenforceable due to inequitable conduct (based on materiality and intent) as Esai had not disclosed to the patent examiner its co pending application (now US4849431 patent) at the time of prosecution of 841’ patent. Teva also said that an article by Dr. Kenley published in Journal of Medicinal Chemistry (JMC) in 1984 further suggest that 841’ invention is obvious and if patent examiner would have known about this patent (431') and JMC article he would have not granted the 841’ patent. Esai produced the testimony by Dr. Kenley who sided with Esai.
The U.S. District Judge Harold Ackerman concluded in his opinion that There is no doubt that Teva has infringed Eisai's valid patent, and Eisai will likely prevail at trial in demonstrating the enforceability of that patent over Teva's inequitable conduct defense
The other para IV filer against this product are Ranbaxy, Par and Roxane
Donepezil (2-[(1-benzyl-4-piperidyl)methyl]- 5,6-dimethoxy-2,3-dihydroinden-1-one), marketed under the trade name Aricept (Eisai), is a centrally acting reversible acetylcholinesterase inhibitor. Its main therapeutic use is in the treatment of Alzheimer's disease where it is used to increase cortical acetylcholine. The USFDA first approved Aricept tablets in 1996. The drug is Tokyo-based Eisai's biggest product, with $2.16 billion in worldwide sales in the year ended in March 2007. (orangebookblog) (Eisai press release)
Teva Press Release
Teva Pharma that the U.S. District Court for the District of New Jersey has granted Eisai's motion for a preliminary injunction related to Teva's tentatively approved Abbreviated New Drug Application (ANDA) to market its generic version of Eisai's Alzheimer's treatment Aricept(R) (Donepezil Hydrochloride) Tablets, 5 mg and 10 mg. The injunction is based on Eisai's enforcement of US4,895,841 that Teva has asserted is unenforceable. A trial date has not been set.
