Oral naltrexone has been shown to reduce alcohol consumption and craving in individuals with alcohol use disorder (AUD), yet evidence regarding the efficacy of the extended-release injectable formulation (XR-naltrexone) is limited. Researchers conducted a systematic review and meta-analysis of 7 randomized controlled trials evaluating 1500 adults with AUD receiving XR-naltrexone (150–400 mg) for 2–6 months or placebo, plus some form of behavioral therapy. The primary outcome was the pooled weighted mean difference (WMD) in drinking days and heavy drinking days per month.
- Compared with patients who received placebo, those who received XR-naltrexone had 2 fewer drinking days and 1.2 fewer heavy drinking days per month.
- Longer treatment duration (>3 months) resulted in 1.9 fewer heavy drinking days per month (WMD, −1.9; 95% CI = −3.2, −0.5; P = 0.01),* compared with treatment duration of <3 months.
- Compared with patients in studies requiring abstinence prior to treatment initiation, patients in studies that did not require lead-in abstinence had 2 fewer heavy drinking days per month (WMD, -2.0; 95% CI = −3.52, −0.48; P = 0.01).*
*Overlap of 95% CIs between subgroups indicate potential lack of statistical significance. However, researchers maintain clinical significance of findings.
Comments: With a modest reduction in drinking days and heavy drinking days per month compared with psychosocial interventions and placebo alone, the results of this meta-analysis suggest that XR-naltrexone may have some efficacy for AUD treatment, especially with longer treatment duration. Further research is needed to determine the long-term efficacy of XR-naltrexone, its effects among an actively drinking population, and how it compares (e.g., efficacy and cost) with oral naltrexone.
Jonah Hamilton† and Seonaid Nolan, MD
† Contributing editorial intern and Research Coordinator, British Columbia Centre on Substance Use.
Reference: Murphy CE 4th, Wang RC, Montoy JC, et al. Effect of extended-release naltrexone on alcohol consumption: a systematic review and meta-analysis. Addiction. 2021;10.1111/add.15572.