Extended-release naltrexone (XR-NTX), a μ-opioid receptor antagonist for prevention of relapse to opioid dependence, has demonstrated efficacy compared with placebo and comparative effectiveness with buprenorphine-naloxone. We report outcomes for XR-NTX in Vivitrol's Cost and Treatment Outcomes Registry.. Please contact the library to request a copy of this article - http://bit.ly/1Xyazai