Marijuana Dependence
Conditions
Keywords
Marijuana, Vilazodone, Contingency management, Motivational enhancement therapy
Brief summary
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.
Detailed description
The purpose of this study is to determine if the medication vilazodone is effective in helping frequent marijuana smokers cut down or stop using marijuana. Vilazodone is FDA approved for the treatment of depression- in this study, vilazodone's effect on marijuana dependence is being investigated. Participation in the study takes 10 visits over a period of approximately two to three months. The first visit is a screening visit to determine if participants are eligible to participate. After the initial assessment visit, the weekly visits take about 30 minutes, with the exception of three therapy sessions which take approximately 60-90 minutes. The three therapy sessions will focus on participant's marijuana use and reasons they may have for stopping or cutting down on use. After completing an initial therapy session, participants will be randomly selected to receive the study medication, either vilazodone or placebo (a capsule that does not contain any active medication). Participants will have weekly study visits with a clinician. At each study visit, they will be asked to fill out forms and answer specific questions concerning their substance use, anxiety symptoms, and feelings in general. They will be providing urine samples to check for illegal drugs of abuse including marijuana and other drugs. They will also have blood samples drawn during to determine if you are taking the medication as directed.
Interventions
DRUGVilazodone
up to 40 mg capsule daily
DRUGPlacebo
up to 40 mg capsule daily
Sponsors
National Institute on Drug Abuse (NIDA)
Medical University of South Carolina
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No
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 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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Percent Marijuana-negative Urine Drug Screens (UDS) | 8 weeks | Participants submitted a urine sample weekly. Percentage of marijuana negative urine samples were calculated per group. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Weekly Cannabis Use Sessions | 8 weeks | Self-report of weekly cannabis use sessions was measured using the Time Line Followback, a calendar-based instrument designed to assess substance consumption. |
| Marijuana Craving and Withdrawal | 8 weeks | The Marijuana Craving Questionnaire (MCQ) is intended to measure marijuana craving in adults. It measures symptoms on four subscales: expectancy, purposefulness, emotionality, and compulsivity. The scale rates individual items from 1 (least craving) - 7 (most craving) with a composite scoring range of 12-84 and possible subscale scoring range of 3-21. It was administered weekly to all participants. Reported here is the mean MCQ purposefulness subscale score across 8 weeks. |
Countries
United States
Participant flow
Recruitment details
Participants recruited between August, 2012 and August, 2014 primarily through media and internet advertisements.
Participants by arm
| Arm | Count |
|---|---|
| Vilazodone Flexible dose up to 40 mg capsule daily
Vilazodone: 40 mg capsule daily | 41 |
| Placebo Flexible dose up to 40 mg capsule daily
Placebo: 40 mg capsule daily | 35 |
| Total | 76 |
Baseline characteristics
| Characteristic | Vilazodone | Placebo | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical Between 18 and 65 years | 41 Participants | 35 Participants | 76 Participants |
| Region of Enrollment United States | 41 participants | 35 participants | 76 participants |
| Sex: Female, Male Female | 11 Participants | 5 Participants | 16 Participants |
| Sex: Female, Male Male | 30 Participants | 30 Participants | 60 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 25 / 41 | 28 / 35 |
| serious Total, serious adverse events | 0 / 41 | 0 / 35 |
Outcome results
Primary
Percent Marijuana-negative Urine Drug Screens (UDS)
Participants submitted a urine sample weekly. Percentage of marijuana negative urine samples were calculated per group.
Time frame: 8 weeks
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Vilazodone | Percent Marijuana-negative Urine Drug Screens (UDS) | 5.5 percentage of UDS |
| Placebo | Percent Marijuana-negative Urine Drug Screens (UDS) | 3.6 percentage of UDS |
Secondary
Marijuana Craving and Withdrawal
The Marijuana Craving Questionnaire (MCQ) is intended to measure marijuana craving in adults. It measures symptoms on four subscales: expectancy, purposefulness, emotionality, and compulsivity. The scale rates individual items from 1 (least craving) - 7 (most craving) with a composite scoring range of 12-84 and possible subscale scoring range of 3-21. It was administered weekly to all participants. Reported here is the mean MCQ purposefulness subscale score across 8 weeks.
Time frame: 8 weeks
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Vilazodone | Marijuana Craving and Withdrawal | 8.9 units on a scale |
| Placebo | Marijuana Craving and Withdrawal | 11.3 units on a scale |
Secondary
Weekly Cannabis Use Sessions
Self-report of weekly cannabis use sessions was measured using the Time Line Followback, a calendar-based instrument designed to assess substance consumption.
Time frame: 8 weeks
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Vilazodone | Weekly Cannabis Use Sessions | 10 weekly cannabis sessions |
| Placebo | Weekly Cannabis Use Sessions | 9.9 weekly cannabis sessions |