Cognitive performance of patients with opioid use disorder transitioned to extended-release injectable naltrexone from buprenorphine: Post hoc analysis of exploratory results of a phase 3 randomized controlled trial.

BACKGROUND: Opioid use disorder (OUD) is associated with cognitive dysfunction. Understanding how pharmacotherapy may affect cognition is an important treatment consideration. METHODS: This was a hybrid residential-outpatient, randomized trial assessing transition regimens (naltrexone/buprenorphine [NTX/BUP] vs placebo-NTX/buprenorphine [PBO-N]/BUP) to extended-release naltrexone (XR-NTX) in patients with OUD seeking BUP discontinuation. Cognition was assessed at baseline, Day 22 (XR-NTX Day 14), and Day 36 (XR-NTX Day 28) using a range of measures (Brief Assessment of Cognition Symbol Coding test, Controlled Oral Word Association Task, Wechsler Memory Scale-III Spatial Span test, Continuous Performance Test, and Test of Attentional Performance). Pre-specified exploratory analyses compared treatment groups. Post hoc analyses were treatment-arm-independent analyses overall and by baseline BUP dose (<8 mg/day [low-dose] or 8 mg/day [higher-dose]). RESULTS: Baseline cognitive measures were similar between NTX/BUP and PBO-N/BUP groups and between BUP low-dose and higher-dose groups. There were improvements in several cognitive outcomes at Day 22 and Day 36 relative to baseline for the overall population, but no differences between NTX/BUP and PBO-N/BUP treatment groups were observed. Participants entering the study on low-dose BUP showed improvements at Day 36 relative to baseline in 5 of 7 cognitive outcomes; participants entering the study on higher-dose BUP generally did not show improvements in cognitive outcomes. CONCLUSIONS: Improvements in most cognitive domains were associated with the transition from BUP to XR-NTX, particularly in participants entering the study on low-dose (<8 mg/day) BUP. These improvements may be due to the discontinuation of BUP, the treatment with XR-NTX, or both.