Effect of Baclofen on Marijuana Withdrawal and Relapse

Only a small percentage of dependent-marijuana smokers who are seeking treatment for their marijuana use are able to achieve sustained abstinence. The objective of this study is to investigate the interaction between marijuana and the potential treatment medication, baclofen, with the direct goal of using this information to improve marijuana treatment outcome. GABAB agonists such as baclofen have been shown to attenuate the self-administration of cocaine, heroin, alcohol and nicotine (see Cousins et al., 2002; Haney et al., 2006). Baclofen also appears to decrease withdrawal symptoms in heroin and alcohol abusers (Akhondzadeh et al., 2000; Addolorato et al., 2000). The purpose of this study is to determine if baclofen dose-dependently decreases marijuana's direct effects and symptoms of marijuana withdrawal and thus decreases marijuana relapse in our laboratory model. 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 each of three medication conditions for 16 days: placebo and baclofen (60, 90 mg/day). Participants will begin taking capsules during the outpatient phase so that the dose can be incremented up to the maintenance dose prior to the first inpatient day. Further, clinical studies have shown that baclofen is most effective at decreasing cocaine's effects when administered for several weeks. During the inpatient study phases, participants will have the opportunity to self-administer placebo or active marijuana 6 times per day. This study will provide important information of the effect of baclofen as a potential treatment medication for marijuana dependence.

Inclusion criteria

• Current marijuana use: average of 3 marijuana cigarettes 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)

Exclusion criteria

• Current, repeated illicit drug use (other than marijuana)
• Presence of significant medical illness(e.g., diabetes, cardiovascular disease, hypertension, examination, laboratory clinically significant laboratory abnormalities)
• History of heart disease
• Request for drug treatment
• Current parole or probation
• Pregnancy or current lactation
• Recent history of significant violent behavior
• Major current Axis I psychopathology(e.g., major depressive disorder, bipolar disorder, suicide risk, schizophrenia)
• Current use of any prescription or over-the-counter medication