HAYWARD, Calif.--(BUSINESS WIRE)--IMPAX Laboratories, Inc. today announced Endo Pharmaceuticals, Inc. (“Endo”) and Penwest Pharmaceuticals, Co. (“Penwest”) have filed suit for patent infringement based on the Company’s amendment to its existing Abbreviated New Drug Application (“ANDA”) for oxymorphone hydrochloride extended-release tablets CII, generic of Opana® ER, adding new 7.5 mg, 15 mg and 30 mg strengths. In connection with this amendment, IMPAX provided notice to Endo and Penwest that its submission includes a Paragraph IV certification stating the Company believes its product does not infringe any valid and enforceable patent, including U.S. Patent Nos. 7,276,250, 5,662,933 and 5,958,456.
