Extended-release pharmacotherapies for substance use disorders in incarcerated populations: A systematic review (2025)

BACKGROUND AND AIMS: Substance use (SU) is prevalent among individuals in the criminal justice system (CJS). However, there is often poor access to treatment. We aimed to assess the effectiveness of two medications, extended-release naltrexone (XR-NTX) and extended-release buprenorphine (XR-BUP) for the prison population.
METHODS: We searched Scopus, OVID/Embase, PubMed/Medline, ProQuest, EBSCO, Cochrane Library and Australian Criminology Database for original articles published from 1 January 2002 to 31 December 2022.
INCLUSION CRITERIA: 18+, substance use disorder; XR treatment; recent incarceration. We extracted study, participants, treatment characteristics and outcome variables. We conducted risk of bias assessments using the RoB-2, ROBINS-I, JBI tools and Evers et al. RESULTS: We identified 25 papers (16 studies) examining 3403 participants. Sixteen papers (9 studies) focused on XR-NTX, eight (7 studies) on XR-BUP and one on both. Eighteen papers (11 studies) were from the US, with the remainder from Norway, Australia, UK, Canada and Germany. There were eight RCTs (10 papers), four secondary observational analyses, four cohort studies, four economic analyses, two case series and one qualitative paper. Most studies had small-moderate samples, with varying retention and follow-up periods. Among RCTs, two XR-NTX studies for opioid use found no difference in retention vs treatment as usual and placebo, while one reported improved retention for XR-NTX implant vs methadone. One RCT showed mixed retention results for XR-NTX vs placebo in alcohol use. One XR-BUP study showed improved or equivalent treatment retention (depending on measures) vs sublingual buprenorphine. There was no difference in overdoses. SU for XR-NTX was challenging to assess due to differing definitions, measures and comparators. XR-BUP yielded mixed SU results, with one indicating a greater effect and another no difference from comparators.
CONCLUSIONS: There is no clear evidence for the effectiveness of extended release naltrexone and buprenorphine among individuals in the criminal justice system compared with shorter acting formulations. But there is growing evidence for the effectiveness of extended release buprenorphine in reducing opioid use and improving treatment retention in that population, with potential cost offsets from initial medication expenses.