Predictors of continued use of extended-released naltrexone (XR-NTX) for opioid-dependence: An analysis of heroin and non-heroin opioid users in Los Angeles County … See original article: Predictors of continued use of extended-released naltrexone (XR-NTX) for opioid-dependence: An analysis of heroin and non-heroin opioid users in Los Angeles County