A major problem in the treatment of opioid dependence has been the persistence of relapse despite detoxification and enforced prolonged abstention from drug use, with or without conventional psychotherapy and other efforts at rehabilitation. Both initial addiction and subsequent relapses are usually ascribed to the quest for opioid-produced euphoria in persons with character disorders. This formulation is in accord with one-half of the common sense "pleasure-pain" principle, but it ignores the other half, namely, the long-lasting dysphoric consequences of re peated opioid use (distressing...