Effect of Quetiapine on Marijuana Withdrawal and Relapse

The purpose of this study is to determine if quetiapine decreases marijuana relapse in a controlled lab setting. For the purposes of this model, relapse is defined as a return to marijuana use after a period of abstinence. The study will utilize an inpatient/outpatient, counter-balanced design, with each participant maintained on placebo and quetiapine (200 mg/day) for 18 days. Participants will begin taking capsules as outpatients so that the dose can be incremented prior to the inpatient phase. While inpatient, participants will have the opportunity to self-administer placebo (0.0%) or active marijuana (6.2%) 6 times per day, depending on the study day. Our laboratory model, which has distinguished the effects of a range of medications on marijuana withdrawal and relapse, will provide important information on the effect of quetiapine as a potential short-term pharmacotherapy to facilitate abstinence in the initial stages of marijuana treatment.

Inclusion criteria

• Current marijuana use:average of 2 marijuana cigarettes per day at least 4 times per week for the past 4 weeks
• Able to perform study procedures
• 21-45 years of age
• Women practicing an effective form of birth control (condoms, diaphragm, birth control, pill, IUD)
• Normal body weight

Exclusion criteria

• Current, repeated illicit drug use (other than marijuana)
• Presence of significant medical illness (e.g., diabetes, cardiovascular disease, hypertension, clinically significant abnormalities)
• History of heart disease or current conduction system disease as indicated by QRS duration > 0.11
• Request for drug treatment
• Current parole or probation
• Pregnancy or current lactation
• Recent history of significant violent behavior
• Major current Axis I psychopathology (major depressive disorder, bipolar disorder, suicide risk, schizophrenia)
• Current use of any prescription or over-the-counter medication
• Prior allergic or otherwise serious adverse reaction to quetiapine