The purpose of this study is to determine the effects of treatment with cabergoline, compared to treatment with placebo, on cocaine induced craving and subjective effects in cocaine-dependent human volunteers.

Secondary aims are to clarify the genetics of substance abuse, potentially leading to improved methods to diagnosis those at risk and to help develop better therapeutic interventions and to develop a new saliva-based test for the detection and measurement of drugs of abuse. As an additional aim, we will also collect blood samples for analyzing a number of genetic polymorphisms.

Inclusion Criteria:

• Be English-speaking volunteers who are not seeking treatment at the time of the study.
• Be between 18-55 years of age.
• Meet DSM-IV TR criteria for cocaine dependence; participants may or may not meet criteria for nicotine dependence. Nicotine dependence is allowed but not required because most cocaine users smoke cigarettes.
• Have a self-reported history of using cocaine by the smoked or IV route.
• Have vital signs as follows: supine blood pressure > 100/65 mm Hg. To ensure that subjects will not be at risk from cocaine, the resting pulse must be < 90 bpm and the blood pressure must be < 150 mmHg systolic and < 90 mmHg diastolic.
• Have hematology and chemistry laboratory tests that are within normal (+/- 10%) limits with the following exceptions: a) liver function tests (total bilirubin, ALT, AST, and alkaline phosphatase) ≤ 3 x the upper limit of normal, and b) kidney function tests (creatinine and BUN) within normal limits.
• Have a baseline EKG that demonstrates clinically normal sinus rhythm, clinically normal conduction, and no clinically significant arrhythmias.
• Have a medical history and brief physical examination demonstrating no clinically significant contraindications for study participation, in the judgment of the admitting physician and the principal investigator.
• Females must have a negative urine pregnancy test during screening and at followup, on day 22.
• Provide a negative urine test for cocaine metabolite on Day 1.

Exclusion Criteria:

• Meet DSM IV TR criteria for dependence on drugs other than cocaine or nicotine.
• Have any history or evidence suggestive of seizure disorder or brain injury.
• Have any previous medically adverse reaction to cocaine, including loss of consciousness, chest pain, or epileptic seizure.
• Have a history of heart valve disease.
• Have any evidence from physical exam of heart murmur.
• Have neurological or psychiatric disorders, such as: psychosis, bipolar illness or major depression as assessed by MINI; organic brain disease or dementia assessed by clinical interview; history of any psychiatric disorder which would require ongoing treatment or which would make study compliance difficult; history of suicide attempts within the past year and/or current suicidal ideation/plan.
• Have evidence of clinically significant heart disease or hypertension, as determined by the PI.
• Have evidence of untreated or unstable medical illness including: neuroendocrine, autoimmune, renal, hepatic, or active infectious disease.
• Have symptomatic HIV or are taking antiretroviral medication.
• Be pregnant or nursing. Other females must either be unable to conceive (i.e., surgically sterilized, sterile, or post-menopausal) or be using a reliable form of contraception (e.g., abstinence, birth control pills, intrauterine device, condoms, or spermicide). All females must provide negative pregnancy urine tests before study entry, upon hospital admission, and at the end of study participation.
• Have asthma or currently use theophylline or other sympathomimetics.
• Have any other illness, condition, or use of psychotropic medications, which in the opinion of the PI and/or the admitting physician would preclude safe and/or successful completion of the study.

Criteria for Discontinuation Following Initiation:

• Inability to comply with study procedures.
• Meet discontinuation criteria due to exaggerated response to cocaine, described below.
• Use cocaine prior to randomization.