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

• Some studies suggest better pharmacotherapy adherence and/or retention rates among non-heroin opioid users compared to heroin users. Therefore, this study examined predictive associations of subsequent doses of extended-release naltrexone (XR-NTX) among heroin and non-heroin opioid users.
• Non-heroin opioid users and heroin users are retained in XR-NTX treatment for comparable periods of time. However, those who identify as homeless, inject opioids (regardless of opioid-type), or were diagnosed with a mental illness are less likely to be retained in treatment with XR-NTX.
• Further, XR-NTX may contribute to decreases in urges to use among heroin and non-heroin opioid users.

Extended-release naltrexone (XR-NTX) is associated with an increased number of opioid-free days, improved adherence rates in substance use disorder treatment programs, and reduced cravings and drug-seeking behaviors. There is little evidence on the predictive associations between baseline characteristics of opioid-dependent patients and XR-NTX utilization. Some studies have demonstrated better pharmacotherapy adherence and/or retention rates among non-heroin opioid users compared to heroin users. This study examines predictive associations between characteristics of patients and XR-NTX utilization, as well as participants’ urge to use opiates. Our findings suggest that XR-NTX may contribute to decreases in urges to use among both heroin and non-heroin opioid users. Non-heroin opioid users and heroin users were retained in XR-NTX treatment for comparable periods of time. However, those who identified as homeless, injected opioids (regardless of opioid-type), or were diagnosed with a mental illness were less likely to be retained in treatment with XR-NTX.