Effectiveness of a Depot Formulation of Naltrexone in Treating Alcohol Dependence

Naltrexone’s
efficacy in treating alcohol dependence is limited by patient non-adherence.
To examine the safety and efficacy of an injectable, depot (sustained-release)
formulation of naltrexone, researchers randomized 315 patients
with alcohol dependence to receive 5 sessions of motivational enhancement
therapy plus monthly naltrexone or placebo injections for 3 months.

• Patients
  in the naltrexone group, compared with those in the placebo group,
  had improvements in the time to heavy-drinking (medians 11 days
  versus 6 days, P=0.05) and gamma-glutamyltranspeptidase
  levels (means 47 units per liter versus 63 units per liter, P=0.10).
• Patients
  receiving naltrexone also had a significantly longer time to
  their first-drinking day (medians 5 days versus 3 days), had
  more days abstinent (means 53 days versus 46 days), and were
  more likely to achieve total (3-month) abstinence (18% versus
  10%).
• There
  were few major differences in the adverse reactions experienced
  by both groups, though patients in the naltrexone group were significantly
  more likely to report >=1 injection site reaction.

Comments:

This study suggests
that a depot formulation of naltrexone is safe and efficacious in
treating alcohol dependence. Given its advantages (e.g., no need to
take a daily dose), injectable naltrexone may be a useful option when
non-adherence hinders an adequate response to oral therapy. At the
time of this report, however, the depot formulation is not available
for clinical use in the United States.

Joseph
Conigliaro, MD, MPH

Reference:

Kranzler HR, Wesson
DR, and Billot L for the Drug Abuse Sciences Naltrexone Depot Study
Group. Naltrexone depot for treatment of alcohol dependence: a multicenter,
randomized, placebo-controlled clinical trial. Alcohol Clin Exp
Res. 2004;28(7):1051–1059.
(view
abstract)