title: Blood naltrexone levels over time following naltrexone implant.
abstract: OBJECTIVE
  Oral naltrexone is used in the management of both heroin and alcohol dependence. However, poor compliance has limited its clinical utility. The study's objective was to determine the period of therapeutic coverage (>or=2 ng/ml) provided by a 3.3 g naltrexone subcutaneous implant compared with existing data on 1.1 g and 2.2 g implants.
  
  
  METHODS
  We assessed free blood naltrexone levels following treatment with a 3.3 g naltrexone implant in heroin dependent patients (n=50) in Perth, Western Australia. Results were compared with previously collated data for patients treated with either a 1.1 g (n=10) or 2.2 g (n=24) implant.
  
  
  RESULTS
  Following 3.3 g naltrexone implant treatment, free blood naltrexone levels remained above 2 ng/ml for 145 days (95% CI 125-167). In comparison, 1.1 g or 2.2 g implant treatment resulted in 95 days (95% CI 69-121) and 136 days (95% CI 114-158) coverage, respectively.
  
  
  CONCLUSIONS
  The 3.3 g implant provides longer therapeutic coverage than the 1.1 g implant but not significantly longer than the 2.2 g implant.
authors.affiliation: School of Psychiatry and Clinical Neurosciences, University of Western Australia, QE II Medical Centre, D Block, Nedlands, Western Australia 6009, Australia.
authors.forename: H T T
authors.initials: HT
authors.lastname: Ngo
authors.forename: D E
authors.initials: DE
authors.lastname: Arnold-Reed
authors.forename: R C
authors.initials: RC
authors.lastname: Hansson
authors.forename: R J
authors.initials: RJ
authors.lastname: Tait
authors.forename: G K
authors.initials: GK
authors.lastname: Hulse
mesh_terms: D000328:Adult; D000437:Alcoholism / Q000097:blood* / Q000188:drug therapy; D016001:Confidence Intervals; D004305:Dose-Response Relationship, Drug; D004343:Drug Implants; D005260:Female; D005500:Follow-Up Studies; D006556:Heroin Dependence / Q000097:blood* / Q000188:drug therapy; D006801:Humans; D008297:Male; D009271:Naltrexone / Q000008:administration & dosage / Q000097:blood*; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000097:blood*; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D004343:Drug Implants; D009292:Narcotic Antagonists; D009271:Naltrexone