A Double-Blind, Placebo-Controlled Trial of the Effectiveness of Memantine in Treating Cocaine Dependence

Memantine is a non-competitive NMDA receptor antagonist that works by decreasing normal excitement in the brain. Dopamine plays a role in the rewarding and addictive properties of cocaine, however, past clinical studies have not been successful in using dopamine agonists in treating cocaine dependent individuals. Non-competitive NMDA receptor antagonists have shown to reduce cocaine-induced dopamine release in animal models and lessen conditioned cocaine cues. This study will evaluate memantine in treating cocaine dependent individuals and its ability to prevent relapse to cocaine use. Specifically, the aim of this study is to determine if memantine is superior to placebo in decreasing cocaine craving, psychological symptoms, functional impairment, and discontinuation of treatment for cocaine abuse.

Participants will enter a 2-week, single-blind, placebo lead-in phase, during which they will visit the clinic three times each week. At each study visit, urine samples and other rating assessments will be collected. In addition, participants will attend weekly therapy sessions. In order to continue in the trial, participants are required to attend at least four out of the first six study visits and both therapy sessions. Eligible participants will then be randomly assigned to receive either memantine or placebo for the duration of the 12-week, double-blind phase of the trial. Study visits will continue to occur three times each week; participants will also receive weekly therapy. Memantine will be taken twice each day. Participants who complete the 12-week trial will enter a 2-week lead-out phase, during which they will be tapered back to a placebo in a single-blind manner. Weekly psychotherapy sessions will continue until the end of Week 14.