Vilazodone Treatment for Marijuana Dependence

• Time to first negative urine drug screen [ Time Frame: 8 weeks ] [ Designated as safety issue: No ]
  Secondary efficacy endpoint is time to first negative (passed) urine screen.
• Percent of marijuana-positive self-reported days [ Time Frame: 8 weeks ] [ Designated as safety issue: No ]
  Secondary efficacy endpoint is percentage of marijuana-positive self-reported days
• Study retention [ Time Frame: 8 weeks ] [ Designated as safety issue: No ]
  Secondary efficacy endpoint is retention in the study.
• Marijuana craving and withdrawal [ Time Frame: 8 weeks ] [ Designated as safety issue: No ]
  Secondary endpoint of marijuana craving and withdrawal

Marijuana is the most commonly used illicit drug, yet few clinical trials have evaluated pharmacotherapy treatments for marijuana dependence. This study will evaluate the efficacy of vilazodone for reducing marijuana use in marijuana-dependent adults. A contingency management intervention (CM)and motivational enhancement therapy (MET)will be incorporated to encourage study engagement and retention, and genomic DNA will be extracted to characterize subjects according to polymorphisms of genes potentially relevant to the activity of vilazodone. It is hypothesized that vilazodone combined with MET and CM will reduce the percent of marijuana-positive urine drug screen results in marijuana-dependent individuals as compared to a placebo treatment combined with MET and CM.

• Drug: Vilazodone
  40 mg capsule daily
• Drug: Placebo
  40 mg capsule daily

• Experimental: Vilazodone
  40 mg capsule daily
  Intervention: Drug: Vilazodone
• Placebo Comparator: Placebo
  40 mg capsule daily
  Intervention: Drug: Placebo

Inclusion Criteria:

• Must meet DSM-IV criteria for marijuana dependence
• Must be between the ages of 18 and 65 years old
• If female and of childbearing potential, must agree to use acceptable method of birth control for duration of the trial.
• Cannabis-positive urine drug screen at screening
• Must consent to random assignment
• Must be able to read and provide informed consent

Exclusion Criteria:

• Women who are pregnant, nursing, or plan to become pregnant during course of study
• Must not have a history of or current psychotic disorder, bipolar disorder, or eating disorder
• Must not meet criteria for current major depressive or generalized anxiety disorder
• Must not pose a current suicidal or homicidal risk
• Must not have evidence or history of serious medical disease
• Must not require concomitant therapy with psychotropic medication or CYP3A4 inhibitors
• Must not be currently dependent on other substances, with the exception of nicotine;
• Patients who, in the investigator's opinion, would be unable to comply with study procedures or assessments