When Aaron, a 33-year-old writer from New York, decided to get help for his five-year addiction to painkillers, there was really only one option. Every morning, he visited a local clinic for a small cup of methadone, the standard treatment for addiction to heroin and other opiates since the 1960's. But his life soon revolved around the clinic's hours, he said, and the daily routine was humiliating. "I had to stand in line with a bunch of people who were talking about getting high," and take a urine test for illicit drugs each week, said Aaron, who spoke on the...