Pharmacokinetics, safety, and tolerability of a depot formulation of naltrexone in alcoholics: an open-label trial.
BACKGROUND
Naltrexone is an effective medication for treatment of alcohol dependence, but its efficacy is limited by lack of adherence to the oral dosage form. A long-acting depot formulation of naltrexone may increase adherence.


METHODS
A single site, 6-week open label study was conducted with 16 alcohol dependent subjects each receiving 300 mg of Naltrexone Depot by intramuscular injection. The main outcomes were safety and tolerability of the Naltrexone Depot formulation, blood levels of naltrexone and its main metabolite 6-beta naltrexol, and self-reported alcohol use. All subjects received weekly individual counseling sessions.


RESULTS
The medication was well tolerated with 88% of subjects completing the 6-week trial. The most common side effect experienced was injection site complications. There were no serious adverse events. Subjects had naltrexone and 6-beta-naltrexol concentrations throughout the trial with mean values ranging from 0.58 ng/mL to 2.04 ng/mL and 1.51 ng/mL to 5.52 ng/mL, respectively, at each sampling time following administration. Compared to baseline, subjects had significantly reduced number of drinks per day, heavy drinking days and proportion of drinking days.


CONCLUSIONS
Naltrexone Depot is safe and well tolerated in alcoholics and these findings support the further investigation of its utility in larger double-blind placebo controlled trials.
Galloway
Gantt P
GP
Haight Ashbury Free Clinics, San Francisco, USA. gantt@itsa.ucsf.edu
Koch
Monika
M
Cello
Ryan
R
Smith
David E
DE
D000293:Adolescent; D000328:Adult; D000368:Aged; D000428:Alcohol Drinking / Q000097:blood / Q000378:metabolism / Q000523:psychology; D000437:Alcoholism / Q000097:blood / Q000188:drug therapy* / Q000378:metabolism; D003692:Delayed-Action Preparations; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D008297:Male; D008875:Middle Aged; D009271:Naltrexone / Q000031:analogs & derivatives / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*; D009292:Narcotic Antagonists / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*; D010349:Patient Compliance; D016896:Treatment Outcome
D003692:Delayed-Action Preparations; D009292:Narcotic Antagonists; C010410:6 beta-hydroxynaltrexone; D009271:Naltrexone