Effects of Low-dose Naltrexone in Combination With a Range of Smoked Marijuana

Study Overview
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Brief Summary
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In heavy marijuana smokers, opioid receptor blockade increases the subjective and cardiovascular effects of marijuana. The current study was designed to clarify opioid-cannabinoid interactions by assessing how naltrexone shifts the dose-response function for marijuana-elicited effects in heavy marijuana smokers. For this within-subject, double-blind study, a marijuana smoking procedure was designed to characterize a dose-response relationship for marijuana's subjective and cardiovascular effects under blinded conditions.

Official Title
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Effects of Low-dose Naltrexone in Combination With a Range of Smoked Marijuana

Conditions
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Marijuana Smoking

Intervention / Treatment
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* Drug: Inactive Marijuana (0% THC)
* Drug: Active Marijuana (5.5% THC)
* Drug: Active Marijuana (6.2% THC)
* Drug: Naltrexone
* Drug: Placebo naltrexone


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Current marijuana use Able to perform study procedures Women practicing an effective form of birth control Exclusion Criteria: Current repeated illicit drug use (other than marijuana) Presence of significant medical illness (e.g., diabetes, cardiovascular disease,hypertension, hepatitis, clinically significant laboratory abnormalities, LFTs > 3x upper limit of normal, blood pressure > 140/90

Ages Eligible for Study
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Minimum Age: 21 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Placebo naltrexone + Inactive marijuana<br>Placebo naltrexone capsules (0mg), inactive marijuana (0% THC). Each study participant underwent 8 conditions in a randomized order. | Drug: Inactive Marijuana (0% THC)<br>* Marijuana cigarette containing 0% THC<br>* Other names: Cannabis;Drug: Placebo naltrexone<br>* Naltrexone (0mg)<br>* Other names: PBO;|
| Placebo Comparator: Placebo naltrexone + Active marijuana (5.5% THC)<br>Placebo naltrexone capsules (0mg), active marijuana (5.5% THC). Each study participant underwent 8 conditions in a randomized order. | Drug: Active Marijuana (5.5% THC)<br>* Marijuana cigarette containing 5.5% THC<br>* Other names: Cannabis;Drug: Placebo naltrexone<br>* Naltrexone (0mg)<br>* Other names: PBO;|
| Placebo Comparator: Placebo naltrexone + Active marijuana (6.2% THC)<br>Placebo naltrexone capsules (0mg), active marijuana (6.2% THC). Each study participant underwent 8 conditions in a randomized order. | Drug: Active Marijuana (6.2% THC)<br>* Marijuana cigarette containing 6.2% THC<br>* Other names: Cannabis;Drug: Placebo naltrexone<br>* Naltrexone (0mg)<br>* Other names: PBO;|
| Experimental: Naltrexone + Active marijuana (5.5% THC)<br>Naltrexone capsules (12mg), active marijuana (5.5% THC). Each study participant underwent 8 conditions in a randomized order. | Drug: Active Marijuana (5.5% THC)<br>* Marijuana cigarette containing 5.5% THC<br>* Other names: Cannabis;Drug: Naltrexone<br>* Naltrexone (12mg/70kg)<br>* Other names: Revia;|
| Experimental: Naltrexone + Active marijuana (6.2% THC)<br>Naltrexone capsules (0mg), active marijuana (6.2% THC). Each study participant underwent 8 conditions in a randomized order. | Drug: Active Marijuana (6.2% THC)<br>* Marijuana cigarette containing 6.2% THC<br>* Other names: Cannabis;Drug: Naltrexone<br>* Naltrexone (12mg/70kg)<br>* Other names: Revia;|
| Placebo Comparator: Naltrexone + Inactive marijuana<br>Naltrexone capsules (12mg), inactive marijuana (0% THC). Each study participant underwent 8 conditions in a randomized order. | Drug: Inactive Marijuana (0% THC)<br>* Marijuana cigarette containing 0% THC<br>* Other names: Cannabis;Drug: Naltrexone<br>* Naltrexone (12mg/70kg)<br>* Other names: Revia;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Subjective Marijuana Effects | Subjective ratings of marijuana's quality and effect ('Strength', 'Good Effect', 'High', 'Stimulation') and craving ('Want Marijuana') as a function of active puffs and naltrexone, using a visual analogue scale with a series of 100 mm long lines labeled 'not at all' at one end (0 mm) and 'extremely' at the other end (100 mm). Participants were instructed to indicate how they felt at that particular moment. Higher ratings indicate more agreement with the statement. | 180 minutes after marijuana administration, during each of 8 outpatient sessions over the course of 3-6 weeks. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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naltrexone, smoked marijuana, marijuana use