This study compares two methods of initiating treatment with extended-release naltrexone (XR-NTX) when implemented at community-based inpatient or residential programs. The primary goal of this hybrid effectiveness-implementation study is to determine whether the Rapid method of initiating treatment with XR-NTX is non-inferior to a standard method on the primary effectiveness outcome of successful initiation of XR-NTX (receiving the first injection while inpatient) when implemented at community-based inpatient or residential programs. Secondary objectives include comparing rapid versus standard method of XR-NTX initiation on: time from admission to first dose of XR-NTX while inpatient and time to dropout, craving, withdrawal severity, retention, abstinence, and safety measures.

The goal of the project is to build a clinical data research infrastructure that will begin to enhance capacity to use electronic health record (EHR) data and patient reported outcomes measures (PROs) to conduct opioid related research in emergency departments (EDs). 200 adult patients with a history of non-medical opioid use, opioid use disorder, or acute opioid overdose will be enrolled and will be asked to complete three PRO surveys (baseline, 3 days post ED discharge, and 30 days post discharge).

The aims of this study are: 1. To evaluate using mixed methods the feasibility and acceptability of OUD screening, ED-initiated BUP, and referral. 2. Over the course of the study and as XR-BUP is added to hospital formularies, to estimate the percentage and confidence intervals of patients assessed, treated, and engaged in treatment at Day 30. This will be a three-site study employing a multi-faceted approach to facilitate clinical protocol implementation and to assess feasibility, acceptability, and impact. Investigators will develop, introduce and update site-specific ED clinical protocols and implementation plans for OUD screening, ED-initiated BUP, and referral for treatment. A participatory action research approach will be utilized along with mixed methods incorporating data derived from: Medical record and administrative data abstraction; Research assessments involving patients who are eligible for and willing to receive ED-initiated BUP (including both those who do, and do not, receive BUP); Qualitative interviews, focus groups, and quantitative assessments involving providers and staff, patients, and other stakeholders.