The purpose of this study is to examine the impact of a medication called oxytocin on marijuana use and therapy response in people who frequently use marijuana.

Oxytocin has been shown to promote trust, social bonding, and calmness; however, its potential additive effects with a therapy intervention have not been explored in marijuana-dependent individuals. In the proposed study, the impact of intranasal oxytocin on therapy effectiveness and marijuana use outcomes following a brief therapy intervention will be investigated. It is hypothesized that oxytocin administration (vs. placebo) will improve treatment satisfaction and decrease marijuana use.

Inclusion Criteria:

1. Subjects must be able to provide informed consent and function at an intellectual level sufficient to allow accurate completion of all assessment instruments.
2. Subjects must meet DSM-IV criteria for current marijuana dependence (within the past three months). While individuals may also meet criteria for abuse of other substances, they must identify marijuana as their primary substance of abuse and must not meet criteria for dependence on any other substance (except nicotine) within the last 60 days.
3. Subjects must consent to remain abstinent from alcohol for 24 hours and other drugs of abuse (except nicotine and marijuana) for three days immediately prior to study procedures. Subjects must abstain from marijuana for 24 hours prior to testing. By restricting marijuana use as proposed, subjects should not be under the acute effects of marijuana.
4. Subjects must consent to random assignment.

Exclusion Criteria:

1. Women who are pregnant, nursing or of childbearing potential and not practicing an effective means of birth control.
2. Subjects with evidence of or a history of significant hematological, endocrine, cardiovascular, pulmonary, renal, gastrointestinal, or neurological disease including diabetes, as these conditions may affect physiological/subjective responses.
3. Subjects with a history of or current psychotic disorder or bipolar affective disorder as these may interfere with subjective measurements.
4. Subjects who pose a current suicidal or homicidal risk.
5. Subjects taking any psychotropic medications, including SRI's or other antidepressants, opiates or opiate antagonists because these may affect test response. Individuals who take stimulants for treatment of ADHD will be allowed to participate.
6. Subjects with any acute illness or fever. Individuals who otherwise meet study criteria will be rescheduled for evaluation for participation.
7. Subjects who are unwilling or unable to maintain abstinence from alcohol and marijuana for 24 hours and other drugs of abuse (except nicotine) for three days prior to study procedures.
8. Subjects meeting DSM-IV criteria for substance dependence (other than nicotine or marijuana) within the past 60 days.
9. Subjects who, in the investigator's opinion, would be unable to comply with study procedures or assessments.

Limitations included small sample size and limited generalizability as individuals with other substance use disorders were excluded from participation.