FILE - U.S. Food and Drug Administration Commissioner Dr. Robert Califf speaks at a news conference at the Hubert H. Humphrey Building in Washington, Thursday, May 5, 2016. Califf says a comprehensive review of the opioid painkillers that triggered the nation's ongoing drug overdose epidemic is in the works. But he faces skepticism about the long-promised review from lawmakers, experts and advocates after years of delay. (AP Photo/Andrew Harnik, File)