title: Treating Opioid Dependence With Injectable Extended-Release Naltrexone (XR-NTX): Who Will Respond?
abstract: OBJECTIVE
  Once-monthly intramuscular extended-release naltrexone (XR-NTX) has demonstrated efficacy for the prevention of relapse in opioid dependence, providing an alternative to agonist or partial agonist maintenance (ie, methadone and buprenorphine). The question remains, for whom is this unique treatment most efficacious and can patient-treatment matching factors be identified?
  
  
  METHODS
  A moderator analysis was conducted on a previously reported 24-week, placebo-controlled, multisite, randomized controlled trial of XR-NTX (n = 126) versus placebo (n = 124) among recently detoxified opioid-dependent adults in Russia, which showed XR-NTX superior to placebo in proportion of opioid abstinent weeks. The moderator analysis examined a dichotomous indicator of good clinical response-achieving at least 90% of weeks abstinent over the 24-week trial. A series of logistic regression models were fit for this outcome as functions of treatment (XR-NTX vs placebo), each baseline moderator variable, and their interactions. The 25 baseline variables included demographics, clinical severity (Addiction Severity Index, SF-36, and Clinical Global Impression-Severity), functioning (EQ-5D), craving, and HIV serostatus (HIV+).
  
  
  RESULTS
  More XR-NTX patients achieved 90% abstinence (64/126, 51%) versus placebo (39/124, 31%; P = 0.002). There were no significant interactions between baseline variables and treatment. There was a significant main effect of Clinical Global Impression-Severity score (P = 0.02), such that higher severity score was associated with a lower rate of Good Clinical Response.
  
  
  CONCLUSIONS
  The absence of significant baseline by treatment interactions indicates that no patient-treatment matching variables could be identified. This suggests that XR-NTX was effective in promoting abstinence from opioids across a range of demographic and severity characteristics.
authors.affiliation: From the New York State Psychiatric Institute and Department of Psychiatry (EVN), Columbia University, New York, NY; Bekhterev Research Psychoneurological Institute and St Petersburg State Pavlov Medical University (EK), Russia; Department of Psychiatry and Biobehavioral Sciences (WL), University of California, Los Angeles, CA; Alkermes, Inc (JZ, AM, BLS), Waltham, MA; and Treatment Research Institute (DRG), Philadelphia, PA.
authors.forename: Edward V
authors.initials: EV
authors.lastname: Nunes
authors.forename: Evgeny
authors.initials: E
authors.lastname: Krupitsky
authors.forename: Walter
authors.initials: W
authors.lastname: Ling
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Zummo
authors.forename: Asli
authors.initials: A
authors.lastname: Memisoglu
authors.forename: Bernard L
authors.initials: BL
authors.lastname: Silverman
authors.forename: David R
authors.initials: DR
authors.lastname: Gastfriend
mesh_terms: D000328:Adult; D003692:Delayed-Action Preparations / Q000008:administration & dosage / Q000627:therapeutic use; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D008297:Male; D008875:Middle Aged; D009271:Naltrexone / Q000008:administration & dosage / Q000627:therapeutic use*; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D009293:Opioid-Related Disorders / Q000188:drug therapy*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D003692:Delayed-Action Preparations; D009292:Narcotic Antagonists; D009271:Naltrexone