• Safety
  

Methadone maintenance is currently the most effective treatment for opioid dependence, but has limitations and is controversial. An alternative pharmacological strategy, naltrexone maintenance, currently has limited usefulness due to poor compliance and low patient acceptability. Preclinical studies and preliminary clinical observations support the use of NMDA receptor antagonists in treating opioid dependence. In humans, NMDA receptor antagonists reduce signs and symptoms associated with opiate withdrawl. In addition, NMDA receptor antagonists reduce subjective effects of heroin and heroin-craving. The primary aim of this study is to test the efficacy of memantine, a noncompetitive NMDA receptor antagonist, in reducing early attrition and improving outcome in opioid-dependent individuals maintained on naltrexone.

This double-blind, 12-week trial will include 165 heroin-dependent patients who completed detoxification. Participants will be randomly assigned to one of three conditions: naltrexone and placebo, naltrexone and memantine (15 mg bid), or naltrexone and memantine (30 mg bid). Naltrexone will be taken 3 times each week at the clinic, while memantine or placebo will be taken at home. In addition, twice each week patients will receive a psychosocial intervention that will include motivational interviewing and cognitive-behavioral relapse prevention. The goal of the psychosocial intervention is to improve compliance with medication and maintain abstinence. Baseline assessments will be taken and compared to those completed at study visits, which will occur 3 times each week. Repeated assessments will also be completed 1, 2, and 3 months following the end of treatment. Primary outcome measures will include retention in treatment at the end of the study and heroin abstinence in the final four weeks prior to the study endpoint.