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.