Pain Therapeutics Inc., of Austin, Texas, is collaborating with the University of Texas, Austin to establish proof of concept around "a well-known, and undisclosed, drug of abuse." The collaboration is unrelated to Remoxy ER (oxycodone), the company said. In November, Pain Therapeutics petitioned the FDA regarding an August complete response letter (CRL) for Remoxy, one of four CRLs the candidate has drawn to date.