Background: Despite widespread use of naltrexone maintenance in many countries for more than a decade, the evidence of its effects has not yet been systematically evaluated.
Objectives: To evaluate the effects of naltrexone maintenance treatment in preventing relapse in opioid addicts after detoxification.
Search strategy: We searched MEDLINE (1973-first year of naltrexone use in humans-July 2000), EMBASE (1974-July 2000), Cochrane Controlled Trials Register (Cochrane Library issue 2001.4) and handsearched the "Bolletino per le Farmacodipendenze e l'Alcolismo" (1978 to 1997) and reference lists of relevant articles. We contacted pharmaceutical producers of naltrexone, authors and other Cochrane review groups. Date of most recent searches: February 2003.
Selection criteria: All controlled studies of naltrexone; treatment of heroin addicts after detoxification.
Data collection and analysis: Reviewers evaluated data independently and analysed outcome measures taking into consideration adherence to and success of the study intervention. Data were extracted and analysed stratifying for the three categories of study quality. Where possible, meta-analysis was performed.
Main results: Eleven studies met the criteria for inclusion in this review, even if not all of them were randomised. The methodological quality of the included studies varied, but was generally poor. Meta-analysis could be performed to a very low degree only, because the studies and their outcome measures were very heterogeneous. A statistically significant reduction of (re-)incarcerations was found for patients treated with naltrexone and behaviour therapy in respect to those treated with behaviour therapy only. The other outcomes considered in the meta-analysis did not yield any significant results. Final conclusions on whether naltrexone treatment may be considered effective in maintenance therapy cannot be drawn from the clinical trials available so far.
Reviewer's conclusions: The available trials do not allow a final evaluation of naltrexone maintenance treatment yet. A trend in favour of treatment with naltrexone was observed for certain target groups (particularly people who are highly motivated), as has been previously described in the literature.