Availability of Extended-Release Naltrexone May Increase the Number of Opioid-Dependent Individuals in Treatment: Extension of a Randomized Clinical Trial

Background and objective: Opioid maintenance treatment (OMT) is highly available in Norway, but only 50% of opioid-dependent individuals are enrolled in such programs. This study was aimed at examining if availability of extended-release naltrexone (XR-NTX) could attract individuals who for different reasons were not enrolled in an OMT program. Methods: In a Norwegian clinical study, n = 117 opioid-dependent adults volunteered to receive XR-NTX in a 9-month period, as an extension of a previous randomized clinical trial. Results: Before study inclusion, 40.2% (n = 47) of the study participants were not enrolled in OMT while the remainder were recruited from OMT. Participants not enrolled in OMT displayed more ongoing severe addiction-related problems such as heroin use (p = 0.002), but displayed a higher retention in treatment in the 9-month extension study (p = 0.048 for log-rank test) than participants enrolled in OMT. Conclusion: Availability of XR-NTX attracted opioid-dependent individuals not previously enrolled in OMT. While OMT may be perceived as a burden with regard to daily intake and control measures, one-monthly injections with XR-NTX may be perceived favourable, offering more freedom to the patients, not having addictive properties, and potentially reducing heroin craving. We suggest that an introduction of XR-NTX in Europe may increase the number of opioid-dependent individuals in treatment.