"Findings from a 24-week randomized controlled trial comparing extended-release injectable naltrexone (Vivitrol, Alkermes) to placebo in individuals with current opioid dependence have been considered in the recent indication for extended-release injectable naltrexone for the treatment of opioid dependence. In this trial, subjects having completed 30-day detoxification were recruited from 13 sites in Russia received either 380 mg intramuscular injections of extended-release naltrexone (n = 126) or placebo injection (n = 124) every 4 weeks for 24 weeks. Primary outcome data of opioid abstinence, measured by urine and self-report as well as secondary data including opioid craving, dependence relapse and study retention were measured. Opioid-free weeks from week 5 to 24 were significantly different between treatment groups (P, 0.0002), with a median of 90% percent of opioid-free urines in the extended-release naltrexone group and 35% in the placebo group. Total abstinence measured as 100% opioid-free weeks in weeks 5 through 24 was 35.7% in the extended-release naltrexone group versus 22.6% in the placebo group. With extended-release naltrexone, subjects reported a 50% mean reduction in subjective craving compared with no change in craving for subjects receiving placebo, and retention in the extended-release naltrexone group was significantly longer compared to the placebo group (168 days vs. 96 days, P = 0.0042).43"
Kjome, Kimberly L. and Moeller, F. Gerard, "Long-Acting Injectable Naltrexone for the Management of Patients with Opioid Dependence," Substance Abuse: Research and Treatment 2011:5 1–9, doi: 10.4137/SART.S5452.