DANBURY, Conn., July 23, 2007 (PRIME NEWSWIRE) -- Penwest Pharmaceuticals Co. (Nasdaq:PPCO) today reported that the U.S. Patent and Trademark Office (PTO) has indicated on its website that a Penwest patent application claiming the sustained-release formulation of oxymorphone related to OPANA(r) ER (oxymorphone HCl) extended-release tablets CII has been allowed.
