Radio talk show host and political commentator Rush Limbaugh put the issue of drug abuse on the front pages a few weeks ago with his admission that he's addicted to the drug OxyContin and other painkillers. OxyContin is the same drug that's perplexed physicians and law enforcement officials in northern Minnesota because its abuse has become one of their biggest problems. Dr. Jon Hallberg is medical director of the University of Minnesota Primary Care Center and our regular medical analyst here on All Things Considered. He says OxyContin presents a particular dilemma.