The lawsuit is in response to Impax’s notice to Endo and Penwest, announced on December 17, 2007, advising of the FDA’s acceptance for substantive review, as of November 23, 2007, of Impax’s abbreviated new drug application (ANDA) containing a Paragraph IV certification for oxymorphone hydrochloride extended-release (ER) tablets CII.
Impax has stated in its Paragraph IV certification notice letter that the FDA requested Impax to provide notification to Endo and Penwest of this certification. Impax’s Paragraph IV certification notice refers to certain Penwest patents listed in the FDA’s Orange Book relating to the formulation of Opana ER. The complaint filed today alleges infringement of certain of these Orange Book-listed patents.