NIDA-CTN-0097

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.