"Our finding that MOUD [Medication for Opioid Use Disorder] treatment with naltrexone was not protective against overdose or serious opioid-related acute care use is consistent with other studies15,35 that found naltrexone to be less effective than MOUD treatment with buprenorphine. The mean (SD) treatment duration for naltrexone in this cohort was longer than prior observational studies at 74.41 (70.15) days.

"Our results demonstrate the importance of treatment retention with MOUD [Medication for Opioid Use Disorder]. Individuals who received methadone or buprenorphine for longer than 6 months experienced fewer overdose events and serious opioid-related acute care use compared with those who received shorter durations of treatment or no treatment. These findings are consistent with prior research11,15,27-29 demonstrating high rates of recurrent opioid use if MOUD treatment is discontinued prematurely. Despite the benefit of MOUD in our study, treatment duration was relatively short.

"In a national cohort of 40,885 insured individuals between 2015 and 2017, MOUD [Medication for Opioid Use Disorder] treatment with buprenorphine or methadone was associated with a 76% reduction in overdose at 3 months and a 59% reduction in overdose at 12 months. To our knowledge, this was the largest cohort of commercially insured or MA individuals with OUD [Opioid Use Disorder] studied in a real-world environment with complete medical, pharmacy, and behavioral health administrative claims.

"In the 12 months after a nonfatal overdose, 2040 persons (11%) enrolled in MMT for a median of 5 months (interquartile range, 2 to 9 months), 3022 persons (17%) received buprenorphine for a median of 4 months (interquartile range, 2 to 8 months), and 1099 persons (6%) received naltrexone for a median of 1 month (interquartile range, 1 to 2 months). Among the entire cohort, all-cause mortality was 4.7 deaths (95% CI, 4.4 to 5.0 deaths) per 100 person-years and opioid-related mortality was 2.1 deaths (CI, 1.9 to 2.4 deaths) per 100 person-years.

"VIVITROL injections may be followed by pain, tenderness, induration, swelling, erythema, bruising, or pruritus; however, in some cases injection site reactions may be very severe. In the clinical trials, one patient developed an area of induration that continued to enlarge after 4 weeks, with subsequent development of necrotic tissue that required surgical excision. In the postmarketing period, additional cases of injection site reaction with features including induration, cellulitis, hematoma, abscess, sterile abscess, and necrosis, have been reported.

"Vulnerability to Opioid Overdose

"Precipitation of Opioid Withdrawal

"What is VIVITROL?
"VIVITROL is a prescription injectable medicine used to:
"• treat alcohol dependence. You should stop drinking before starting VIVITROL.
"• prevent relapse to opioid dependence, after opioid detoxification.
"This means that if you take opioids or opioid-containing medicines, you must stop taking them before you start receiving VIVITROL. See “What is the most important information I should know about VIVITROL?”

"There are currently no specific clinical guidelines for transitioning patients with opioid use disorder to Vivitrol while minimizing the risk of precipitating withdrawal and relapse.²⁵ However, a number of opioid detoxification and induction strategies are being investigated to assist patients transitioning to Vivitrol.^90,91 The US prescribing recommendation that individuals abstain from opioids for seven to 10 days, combined with conventional methods of opioid-agonist tapering over several days, represents a delay of at least two weeks before Vivitrol can be started.

"This large multicentre, randomised, controlled, comparative effectiveness trial had five major findings. First, it was more difficult to start XR-NTX [Extended-release naltrexone] treatment than BUP-NX [sublingual buprenorphine-naloxone] treatment: 28% dropped out of treatment before XR-NTX induction versus only 6% before BUP-NX induction. Second, nearly all induction failures had early relapse. Third, in the intention-to-treat population of all patients who were randomly assigned, XR-NTX had lower relapse-free survival than BUP-NX, directly related to early induction failure.