Eisai sues Teva for patent infringement

Japanese pharmaceutical company Eisai Inc. has filed a lawsuit against Teva Pharmaceutical Industries for patent infringement over Teva's generic version of Aricept, used for the treatment of Alzheimer's disease. The suit was filed in response to Teva's submission to the US Food & Drug Administration of an abbreviated new drug application (ANDA) for Aricept, the main ingredient of which is donepezil hydrochloride. Eisai said in a statement Thursday that it holds a patent on the donepezil component of the drug which is valid until November 25, 2010, and that it would "vigorously enforce and defend that patent." Investors were not too concerned about the suit, however, as Teva shares continued to rise following the Jerusalem-based company's announcement Wednesday that it received final FDA approval for its ANDA to market Oxycodone Extended Release Tablets in 10 mg, 20 mg and 40 mg. sizes. The tablets are the generic equivalent of Purdue Pharma's Oxycontin tablets, for the treatment of pain when continuous analgesia is needed for an extended period of time. Teva said it would start shipping the drugs immediately, thus entering a $1.2 billion brand and generic market for the product. Teva shares rose 1.4% on Wednesday's announcement and a further 2.5% to close at NIS 204 on Thursday.