Intramuscular extended-release naltrexone: current
ANNALS OF THE NEW YORK ACADEMY OF SCIENCES
Issue: Addiction Reviews
Intramuscular extended-release naltrexone: current
evidence
David R. Gastfriend
Alkermes, Inc., Waltham, Massachusetts
Extended-release naltrexone (XR-NTX; Vivitrol␣R ), developed to address poor adherence in addictive disorders, is approved for use in alcohol and opioid-dependence disorders. In alcohol-dependent adults with 4-day initial abstinence, XR-NTX increased initial and 6-month abstinence. An fMRI study found that XR-NTX attenuated the salience of alcohol visual and olfactory cues in the absence of alcohol, and post hoc analyses demonstrated efficacy even during high cue-exposure holiday periods. Safety and tolerability have generally been good, without adverse hepatic impact or intractable acute pain management. XR-NTX use appears feasible in primary care and public systems, and retrospective claims analyses have found cost savings and decreased intensive service utilization relative to oral agents. In opioid dependence, following detoxification, XR-NTX shows efficacy for maintaining abstinence, improving retention, decreasing craving, and preventing relapse. Trials are also exploring its use for the treatment of stimulant dependence. XR-NTX appears compatible with counseling and self-help attendance. While more research is needed, current findings suggest that a formulation of naltrexone that was sought beginning over three decades ago is fulfilling its promise as an extended-release pharmacotherapeutic.
