Psychopathology, craving, and mood during heroin acquisition: an experimental study.

Six detoxified addict volunteers were allowed to self-administer intravenous heroin on an essentially self-determined schedule. Two periods of heroin acquisition were compared: an unmodified cycle in which patients could become intoxicated and a later cycle in which the effects of heroin were blocked with a narcotic antagonist. In the unblocked condition, patients initially experienced an increase in positive mood, but with chronic administration there was a significant rise in psychopathology and the development of a generalized dysphoric state. Similar changes did not occur when the same patients took heroin while blocked with a narcotic antagonist. Drug craving rose dramatically when "unblocked" heroin was available, but gradually fell during methadone detoxification. Following treatment with a narcotic antagonist, the presence of heroin failed to elicit any sustained rise in craving and drug taking was dramatically reduced.