This 12-week study examined the bioavailability, tolerability, and potential efficacy of an injectable sustained-release preparation (SRP) of naltrexone (NTX). Twenty alcohol-dependent subjects took NTX 50 mg po daily for 2 weeks, followed by a 2-week, no-medication Washout Period, a 4-week Injection Period, and a 4-week Follow-up Period. Fifteen subjects (75%) received a single subcutaneous injection of 206 mg of sustained-release NTX, and five subjects (25%) received a placebo injection. All subjects also received eight weekly coping skills sessions during the Oral NTX, and the Washout and Injection Periods.
Results: After injection, NTX plasma concentrations exceeded a mean of 1 ng/ml for 21 days. Adverse effects produced by the SRP of NTX were comparable with those resulting from oral NTX therapy. Compared with placebo, the SRP of NTX significantly reduced the frequency of heavy drinking days during the Injection and Follow-up Periods.
Conclusions: The results of this preliminary study support the potential clinical utility of the SRP of NTX for treatment of alcohol dependence.