Objectives
Cannabinoids are most commonly administered via smoking. Oral consumption in medications, teas, oils, or food also is widely utilized. Additionally, cannabis vaporization followed by inhalation for medical and illicit administration is common. Differences in cannabis pharmacodynamics and pharmacokinetics between these three administration routes and in occasional and frequent cannabis smokers are not thoroughly characterized. This study evaluates cannabis pharmacodynamics and pharmacokinetics in occasional and frequent smokers after smoked, vaporized, and oral cannabis administration.
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Study Population
Up to 80 healthy cannabis smokers, aged 18-50, without a history of adverse reactions to cannabis will be recruited. For dosing sessions 1-4, ten occasional smokers (smoking frequency greater than or equal to 2 times/month but \<3 times/week) and ten frequent smokers (smoking frequency generally greater than or equal to 5times/week) are required. For the optional 5th session, 8-20 participants (regardless of smoking history) are required.
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Study Design
Occasional and frequent cannabis smokers are recruited to participate. Prior to dosing sessions, there is a training visit for all study procedures. Sessions 1-4 are 3 and 4 days each for occasional and frequent cannabis smokers, respectively, and the study design is double blind, double dummy, randomized, crossover, and placebo-controlled. In each session, participants will consume a placebo or active oral (baked in a brownie) cannabis (6.9% 9-tetrahydrocannabinol \[THC\]) dose followed by either placebo or active smoked or vaporized cannabis. Only one active dose will be administered in each dosing session. Whole blood, oral fluid, urine, dried blood spots, and breath are collected throughout all sessions. Due to the large THC body burden stored in the tissues, we will collect biological specimens for a longer period in frequent cannabis smokers than for occasional cannabis smokers. An optional 5th dosing session will be offered in which participants receive a single oral cannabis dose for pharmacokinetic monitoring. The placebo cannabis plant material has a low THC concentration. As we are expecting that the active brownie dose might result in low THC oral fluid contamination, it is necessary to have an active brownie THC dose that is not followed by placebo vaporizer or smoked cannabis. Occasional smokers may stay or be discharged between sessions, including between the 4th and optional 5th dosing session, but dosing must not exceed self-reported intake frequency. Frequent smokers must be discharged for at least 72 h between dosing sessions 1-4, and must stay on the unit at the end of session 4 for session 5 if they choose to participate. The difference between requirements for occasional and frequent smokers to participate in the optional 5th dose is due to the potential confound of low THC concentrations in frequent smokers that might not permit the detection of low THC concentrations after consumption of a low oral THC dose. Occasional cannabis smokers will reside on the closed research unit for approximately 72 h for dosing sessions 1-4, and for approximately 66 h for dosing session 5. Frequent cannabis smokers will reside on the closed research unit for approximately 90 h for dosing sessions 1-3 (and 4 if not participating in optional session 5). If a frequent smoker chooses to participate in dosing session 5, they will remain on the unit for approximately 162 h for sessions 4 and 5. Participants will complete a battery of subjective, objective, and neurocognitive tests before and after dosing. Subjective effects are assessed with visual analog scales. Objective measurements include physiological measurements, expired carbon monoxide, reddening of the conjunctivae and tests measuring psychomotor skills and cognitive functions.
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Outcome Parameters
Primary outcome measures include subjective and objective assessments, performance on neurocognitive tasks, and cannabinoid concentrations in whole blood, oral fluid, urine, dried blood spots, and breath. Correlations between cannabinoid concentrations in whole blood, dried blood spots, oral fluid, and breath will be investigated, the Oral Fluid Working Group for the Partnership for Clean Competition oral fluid screening algorithm will be evaluated, and the pharmacokinetic profiles of alternative cannabinoids will be characterized. Secondary investigations include comparing cannabinoid stability in dried blood spots and whole blood, evaluating the World Anti-Doping Agency urine 11-nor-9-carboxy-THC decision limit, characterizing the performance of the Alere DDS2 on-site oral fluid screening device, and evaluating effects of acute cannabis administration on leptin and other appetitive peptides.\<TAB\>
