The need for longer-term treatment with extended-release naltrexone: a 52-week naturalistic clinical study in patients with opioid use disorder

Abstract Background The utilization of extended-release naltrexone (XR-NTX) as a treatment for opioid use disorder (OUD) is limited, because it is accessible in only a few countries. Although effective and safe for short-term treatment, there are limited long-term data and no formal guidelines for treatment duration. This study aimed to examine the retention, safety, and effectiveness of XR-NTX among participants who chose to continue treatment for an additional 28 weeks beyond the initial 24-week period, and to explore their perceived need for treatment even beyond 52 weeks. Methods The NaltRec study is a naturalistic multicenter clinical trial of XR-NTX treatment in opioid-dependent individuals aged 18–65 years. This paper reports on 80 participants who completed the initial 24-week study and chose to continue XR-NTX treatment for an additional 28-week period. Every four weeks, participants received XR-NTX injections (380 mg), and assessments were conducted to measure treatment retention; opioid, alcohol, and substance use; heroin craving levels; treatment satisfaction; and adverse events. For those who completed 52 weeks of treatment, the perceived need for further extended treatment was also evaluated. Results Of the 80 participants, 50 completed 52 weeks of treatment. The mean treatment duration was 46.2 weeks. A significant reduction in opioid use was observed during the 28-week study period, with two distinct groups identified: Group 1 (87.5%) reported a maximum of one day of opioid use per four weeks, whereas Group 2 (12.5%) reported more than one day per four weeks. The participants reported low craving scores and high treatment satisfaction. No new serious adverse events were reported. Among the completers, the median perceived need for further additional treatment was one more year. Conclusions This exploratory study suggests that continuing XR-NTX beyond 24 weeks may be associated with sustained retention and reduced opioid use and craving among patients with OUD who choose treatment in a setting where agonist therapy is freely available. We suggest that for individuals with OUD who do not wish to receive agonist therapy, XR-NTX should be considered an alternative treatment option and included in more countries, with treatment duration of up to two years. Trial registration Clinicaltrials.gov # NCT03647774, first registered on August 28, 2018. Protocol version #6.1.