The Effect of Brief Potent Glutamatergic Modulation on Cocaine Dependence

he study will begin with an inpatient phase (phase 1) of 5 days, during which abstinence is achieved, followed by a 4 week outpatient phase (phase 2). A single infusion of ketamine or midazolam will occur on day 3 of Phase 1. In addition to measures of mindfulness and impulsivity, stress sensitivity tests are incorporated into the design in order to elucidate mechanisms of action. The study hypotheses are: 1. ketamine and MBRP will significantly increase the time to first use compared to placebo and MBRP in cocaine-dependent individuals. 2. ketamine and MBRP is significantly more likely to lead to abstinence from cocaine (no use over one week) as compared to placebo and MBRP. 3. ketamine and MBRP will significantly reduce subjective, endocrine, and physiological responses to stress (including cue exposure) as compared to placebo and MBRP. 4. ketamine and MBRP will significantly increase mindfulness, as assessed by the Five Facet Mindfulness Questionnaire (FFMQ), as compared to placebo and MBRP.