A randomised, controlled trial of low dose naltrexone for the treatment of opioid dependence.
To investigate the efficacy of low doses of naltrexone in relapse prevention for heroin dependence. Double blind, randomised comparison of three groups-Group 1 taking 50mg per day, Group 2: 0.5mg per day, and Group 3: 0.05 mg per day. Sixty-six dependent heroin users. After detoxification followed by 1 week on 50mg per day naltrexone, participants were randomised to trial medication. All were offered counselling and monitored with weekly clinical reviews. Research interviews were conducted at three and 6 months. Retention in treatment and heroin use at 3 and 6 months. Secondary outcome measures were side effects and craving. Mean days retained in randomised treatment were-Group 1: 58.9 days; Group 2: 46.6 days; and Group 3: 47.8 days. Differences in retention were not significant using survival analysis. However, nine of the first 60 participants, transferred to the 50 mg dose, and one transferred to a lower dose (chi-square = 0.142; P = 0.018). At follow-up, there was no relationship between abstinence from heroin and naltrexone dose, nor between level of heroin use and dose. There were no differences between groups in craving or depression. Low doses of naltrexone had no discernible advantage, and participants preferred 50mg per day. Despite preference for blocking doses of naltrexone, outcomes appeared to be independent of naltrexone dose.