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Research Summary

Naltrexone Implantation versus Methadone Maintenance for Heroin Dependence: Impact on Drug-Related Hospitalization

Long-lasting formulations of naltrexone are increasingly used in treating opioid dependence, but their long-term safety and effectiveness compared with methadone maintenance (MM) are uncertain. In a retrospective longitudinal study using data from comprehensive regional hospital records, researchers in Western Australia compared drug-use–related outcomes in heroin-dependent persons preceding and following treatment with either naltrexone implantation therapy (NIT) (n=314) requiring reimplantation every 6 months or MM (n=522) over similar time periods. Results were as follows:


  • Patients treated with NIT had a substantial decrease in opioid overdose admissions (odds ratio [OR], 0.23) at 3½ years, and had a marked increase in nonopioid overdose admissions at 6 months (OR, 16.3) that did not persist after 3½ years of follow-up. Other nonopioid-related admissions also increased in the NIT group at 6 months and 3½ years (OR, 2.54 and 1.52, respectively).
  • Patients treated with MM had no change in opioid overdose admissions, and had an increase in nonopioid overdose admissions at 6 months (OR, 5.03) that did not persist after 3½ years of follow-up.


Implantable naltrexone may be associated with reductions in opioid overdose, but substantial increases in adverse outcomes associated with nonopioid drug use were observed. Although pre- and posttreatment comparisons are appropriately made using these data, the study design does not allow for meaningful comparisons between NIT and MM groups, nor was it powered to look at mortality. Prospective assessment of diverse outcomes is needed to better define the effectiveness of NIT. Clinicians must be alert to increases in nonopioid drug use among heroin users initiating pharmacotherapy for opioid dependence. Marc N. Gourevitch, MD, MPH


Ngo HT, Tait RJ, Hulse GK. Comparing drug-related hospital morbidity following heroin dependence treatment with methadone maintenance or naltrexone implantation. Arch Gen Psychiatry. 2008;65(4):457–465.