Abstract
Naltrexone is an opioid antagonist which binds competitively at the opioid receptors and blocks the effects of exogenous opioids. Naltrexone has been used to facilitate withdrawal (in using rapid and ultra rapid withdrawal techniques). The research on the efficacy of rapid and ultra-rapid withdrawal to date is extremely limited. The predominant use of naltrexone is as a post-withdrawal relapse prevention intervention. Research has revealed that naltrexone's acceptability is generally poor, mainly appealing to those highly motivated towards achieving and maintaining abstinence. In spite of poor acceptibility, naltrexone-treated participants often produce lower levels of craving for opiates, significantly higher rates and longer periods of abstinence and significantly greater improvement in psychosocial functioning than those treated with placebos and standard treatment programmes. The studies of highly motivated participants demonstrated the highest retention and completion rates. Being employed and having good social support have been identified as being associated with successful outcome. There also appears to be a trend towards greater success being associated with older participants, and those with a greater number of previous treatment attempts. The combined use of naltrexone and psychosocial therapy has proved to be more effective than psychosocial therapy alone, and more effective than naltrexone treatment alone, in improving post treatment outcome. Future research directions are summarized.