Vivitrol Treatment for Cannabis Use Disorder

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.

Eligibility Criteria:
Inclusion Criteria:

* Adult (18-64) male or female (gender to be analyzed as a covariate)
* Understand and willing to comply with study requirements and restrictions
* Willing to use appropriate contraceptive method throughout the study
* Otherwise healthy as judged by investigator based on medical history, physical exam, vitals, ECG and labs
* DSM 5 criteria for current CUD
* Report cannabis as primary drug of abuse
* Have cannabis positive urine drug screen
* Treatment seeking cannabis smoker

Exclusion Criteria:

* Meets DSM 5 criteria for a current axis I disorder including substance use disorder other than cannabis, nicotine or caffeine dependence.
* Unstable medical conditions
* Pregnant or breast-feeding
* Positive urine drug test for opioids (including methadone, morphine, buprenorphine) or benzodiazepines (unless prescribed) at baseline
* Any IM gluteal administration 30 days prior to baseline
* Participation in a clinical trial of a pharmacological agent within 30 days prior to baseline
* Known intolerance and/or hypersensitivity to naltrexone, carboxymethylcellulose, or polylactide-coglycolide
* Any finding that, in the view of the principal investigator, would compromise the subject's ability to fulfill the protocol visit schedule or visit requirement (e.g. unadjudicated charges and/or pending parole hearings)