Opiate antagonists and the modification of heroin self-administration behavior in man: an experimental study.

The heroin self-administration behavior of 8 inpatient heroin addicts was examined for 10 days under blocked (i.e., following ingestion of narcotic antagonists--naloxone or naltrexone) and unblocked (no antagonist) conditions. In the unblocked state, subjects injected all the available heroin, but they ceased heroin use almost completely following antagonist administration. Possible explanations for these results are discussed along with their implications for treatment.