Participants randomized to XR-NTX had a substantial induction hurdle: fewer successfully initiated XR-NTX than BUP-NX, resulting in a higher rate of 24-week relapse events for the XR-NTX group. Among participants successfully inducted to treatment, however, 24-week relapse events were similar across study groups. Self-reported opioid craving was initially less with XR-NTX than with BUP-NX (p=0.0012), then converged by week 24 (p=0.20). With the exception of mild-to-moderate XR-NTX injection site reactions, treatment-emergent adverse events including overdose did not differ between treatment groups.
In this population, it is more difficult to initiate patients to XR-NTX than to BUP-NX, and this negatively affected overall relapse. However, once initiated, both medications were equally safe and effective.
Primary Outcomes Article: Lee JD, et al. Comparative Effectiveness of Extended-Release Naltrexone Versus Buprenorphine-Naloxone for Opioid Relapse Prevention (X:BOT): A Multicentre, Open-Label, Randomised Controlled Trial. The Lancet 2018;391(10118):309-318. [get article]