Glutamatergic Modulation of Cocaine-related Deficits

Inclusion Criteria

1. Active free-base cocaine dependence (at least 4 days of use over the past month, with at least 1 use per week); if the participant uses through another route (IN, IV), then the FB route is dominant (> 80% of occasions).
2. Physically healthy
3. No adverse reactions to study medications
4. 21-52 years of age
5. Normal body weight
6. Responsive to drug cues
7. Capacity to consent

Exclusion Criteria:

1. Seeking treatment or abstinence
2. DSM IV criteria for substance dependence (other than methamphetamine, cocaine, cannabis, or nicotine), or DSM IV criteria for abuse of ketamine or lorazepam
3. DSM-IV criteria for other Axis I psychiatric illness that may make participation hazardous such as schizophrenia, schizoaffective disorder, psychosis NOS, MDD, psychosis secondary to substances, or bipolar disorder
4. Delirium, Dementia, Amnesia, Cognitive Disorders, or dissociative disorders
5. Current suicide risk or a history of suicide attempt within the past 2 years
6. Current use of prescribed psychotropic medication
7. Pregnancy, nursing, or had a baby within the past 6 mo.
8. Heart disease as indicated by history, abnormal ECG, previous cardiac surgery.
9. Unstable physical disorders which might make participation hazardous such as end-stage AIDS, hypertension (>140/90), anemia, active hepatitis or other liver disease, or diabetes
10. "Bad" reaction/experience with prior exposure to ketamine or lorazepam
11. History of significant violence
12. First degree relative with a psychotic disorder