Comparative efficacy of naltrexone-accelerated versus sublingual buprenorphine in opioid withdrawal management and initiating injectable naltrexone treatment: study protocol for a randomized controlled trial.

BACKGROUND: Extended-release injectable naltrexone (XR-NTX), a long-acting opioid antagonist, is an effective relapse prevention strategy in the treatment of opioid use disorder (OUD). However, standard XR-NTX initiation requires completion of opioid withdrawal management and a 1-2 week opioid-free period. This interval is associated with heightened vulnerability to lapse and relapse, and many patients fail to initiate XR-NTX treatment successfully. Therefore, alternative strategies that enable rapid XR-NTX initiation are needed. This study aimed to compare the effectiveness and safety of naltrexone-accelerated (NA) versus sublingual buprenorphine (SB) withdrawal management in facilitating XR-NTX initiation among patients with OUD.

METHODS: This single-center, open-label, randomized controlled trial uses a parallel-group design. Eligible patients aged 18-60 years with moderate to severe OUD who are actively using opioids and are not receiving regular maintenance treatment with methadone or buprenorphine are randomly assigned to one of two groups: (1) NA withdrawal management, comprising one day of adjunctive non-opioid medications, one day of buprenorphine administration, one day of washout, and four days of gradual oral naltrexone titration (1, 3, 12, and 25 mg/day); or (2) SB withdrawal management, comprising one day of adjunctive non-opioid medications, six days of buprenorphine tapering (up to 8 mg on Day 2, 6 mg on Day 3, 4 mg on Days 4-5, 2 mg on Day 6, and 1 mg on Day 7), and a seven-day washout period. Adjunctive non-opioid medications in both groups comprised clonidine, clonazepam, gabapentin, and trazodone. The primary outcomes are the proportions of participants who (1) achieve a negative urine drug test for the assessed opioids and (2) receive XR-NTX at the end of the withdrawal management period. Secondary outcomes include severity of withdrawal symptoms, opioid craving intensity, and adverse effects. All analyses are conducted according to the intention-to-treat principle.

DISCUSSION: The findings of this trial may provide clinically relevant evidence to support rapid initiation of XR-NTX treatment in patients with OUD and inform clinical practice.

CLINICAL TRIAL REGISTRATION: https://en.irct.ir/trial/81525, Iranian Registry of Clinical Trials IRCT20250123064499N1.