A Randomized Trial Comparing Extended-Release Injectable Suspension and Oral Naltrexone, Both Combined With Behavioral Therapy, for the Treatment of Opioid Use Disorder

Abstract

OBJECTIVE: The oral formulation of the opioid antagonist naltrexone has shown limited effectiveness for treatment of opioid use disorder due to poor adherence. Long-acting injection naltrexone (XR-naltrexone), administered monthly, circumvents the need for daily pill taking, potentially improving adherence, and has been shown to be superior to placebo in reducing opioid use over 6 months of treatment. This open-label trial compared the outcomes of patients with opioid use disorder treated with XR-naltrexone or oral naltrexone in combination with behavioral therapy. METHOD: Sixty opioid-dependent adults completed inpatient opioid withdrawal and were transitioned to oral naltrexone. They were stratified by severity of opioid use (six or fewer bags versus more than six bags of heroin per day) and randomly assigned (1:1) to continue treatment with oral naltrexone (N=32) or XR-naltrexone (N=28) for 24 weeks. The first dose of XR-naltrexone (380 mg) was administered prior to discharge, with monthly doses thereafter, and oral naltrexone was given in a 50-mg daily dose. All participants received weekly behavioral therapy to support treatment and adherence to naltrexone. RESULTS: A Cox proportional hazards model adjusting for race, gender, route of use, and baseline opioid use severity indicated that significantly more patients were retained in treatment for 6 months in the XR-naltrexone group (16 of 28 patients, 57.1%) than in the oral naltrexone group (nine of 32 patients, 28.1%) (hazard ratio=2.18, 95% CI=1.07, 4.43). CONCLUSIONS: Patients receiving XR-naltrexone had twice the rate of treatment retention at 6 months compared with those taking oral naltrexone. These results support the use of XR-naltrexone combined with behavioral therapy as an effective treatment for patients seeking opioid withdrawal and nonagonist treatment for preventing relapse to opioid use disorder.