The purpose of this study is to investigate the safety and effectiveness of 12 weeks treatment with an extended-release injectable form of naltrexone (Vivitrol) combined with a psychological intervention in 10 treatment-seeking adults with Cannabis Use Disorder. The hypotheses are that Vivitrol combined with a psychological intervention will be well tolerated, and will reduce cannabis use, improve abstinence rates, and reduce cannabis withdrawal and craving.
This study will be an open-label trial, with no placebo control. Ten male or female treatment-seeking adults with Cannabis Use Disorder (CUD) will be recruited. All participants will receive 3 x 4ml intramuscular injections of Vivitrol (380mg naltrexone). Injections will be administered once every 4 weeks for 12 weeks. In addition, all participants will receive a weekly psychological intervention (Motivational Enhancement Therapy and Cognitive Behavioral Therapy; MET/CBT) for 12 weeks. The aim of this study is to investigate if the proposed Vivitrol dosing schedule, combined with MET/CBT, is appropriate for subsequent randomized controlled trials in people with CUD. This will be achieved by assessing the safety and effectiveness of 12 weeks open-label treatment with Vivitrol (3 x 4 ml intramuscular injections, 380mg naltrexone) combined with weekly MET/CBT. Safety will be assessed by monitoring adverse events during the 12 week treatment period, and up to 3 months follow-up. Effectiveness will be assessed after 12 weeks of treatment and at 3 month follow-up using: (1) seven-day point prevalence cannabis abstinence, (2) percentage of days of cannabis use, (3) amount of cannabis use, and (4) effects on withdrawal symptom scores, craving scores and number of urine samples screened positive for cannabis use.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
1
Three 4ml intramuscular injections of naltrexone 380mg (Vivitrol) administered over 12 weeks (one injection every 4 weeks)
Weekly Motivational Enhancement Therapy and Cognitive Behavioral Therapy (MET/CBT), based upon the Brief Counselling for Marijuana Dependence Manual published by the Substance Abuse and Mental Health Services Administration (SAMHSA), for 12 weeks
Centre for Addiction and Mental Health
Toronto, Ontario, Canada
Dropouts Due to Serious Adverse Events
Tolerability will be measured by the number of participants that drop out of the study because of serious adverse events. Adverse events will be monitored weekly during the 12 week treatment phase of the study
Time frame: At end of 12 weeks treatment
Dropouts Due to Serious Adverse Events
Tolerability will be measured by the number of participants that drop out of the study because of serious adverse events. After the treatment phase of the study adverse events will be monitored weekly for the first 4 weeks follow-up, and then monthly until the final follow-up at 3 months post-treatment
Time frame: At 3 months follow-up
Cannabis Abstinence
Seven-day point prevalence of cannabis abstinence. Abstinence will be measured using a self-report timeline follow-back (TLFB) calendar method, and will be confirmed by urine drug screens.
Time frame: At end of 12 weeks treatment
Cannabis Abstinence
Seven-day point prevalence of cannabis abstinence. Abstinence will be measured using a self-report timeline follow-back (TLFB) calendar method, and will be confirmed by urine drug screens.
Time frame: At 3 month follow-up
Days Cannabis Use
Percentage of days of cannabis use. This will be calculated using a self-report timeline follow-back (TLFB) calendar method
Time frame: During 12 weeks of treatment and up to 3 month follow-up
Amount Cannabis Use
Amount of cannabis used (grams per week). The amount of cannabis consumed will be measured using a self-report timeline follow-back (TLFB) calendar method
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Time frame: During 12 weeks of treatment and up to 3 month follow-up
Cannabis Withdrawal
Withdrawal symptom scores. Cannabis withdrawal symptoms will be measured using the Marijuana Withdrawal Checklist (MWC). The 16 item MWC indicates severity of withdrawal in the previous 24 hours. Each item is scored 0-4 (where 4=severe) and the scale is summed. The outcome variable is the total score (the sum of each individual item score), which can vary from 0 to 64; higher scores indicate a worse outcome (i.e., more number/severity of withdrawal symptoms).
Time frame: During 12 weeks of treatment and up to 3 month follow-up
Cannabis Craving
Craving symptom scores. Cannabis craving will be measured using the Marijuana Craving Questionnaire (MCQ). The 12-item MCQ assesses craving along 4 dimensions: compulsivity, emotionality, expectancy, and purposefulness. Each subscale is the sum of 3 items from the questionnaire. Each item is rated from 1 (strongly disagree) to 7 (strongly agree). Each subscale can thus vary from 3 to 21, where higher scores represent more craving (worse outcome).
Time frame: During 12 weeks of treatment and up to 3 month follow-up
Urine Cannabis Screens
Number of urine samples positive for cannabis use. Urine samples will be collected to perform THC metabolite analysis
Time frame: During 12 weeks of treatment and up to 3 month follow-up