A within-subject cross-over trial comparing the acute effects of vaporized delta-8-tetrahydrocannabinol and delta-9-tetrahydrocannabinol in healthy adults

Abstract

Background: The prevalence and accessibility of Delta 8-tetrahydrocannabinol (Delta 8-THC), a chemical isomer of Delta 9-tetrahydrocannabinol (Delta 9-THC), has increased drastically, yet no controlled studies have directly compared the effects of vaporized Delta 8-THC and Delta 9-THC . Methods: Twenty healthy adults with no past-month cannabis exposure completed five randomized outpatient sessions in a within-subjects, double-blind, crossover design. Participants inhaled Delta 8-THC (10, 20, 40 mg), Delta 9-THC (20 mg), or placebo (distilled water) using the Mighty Medic vaporizer. Measures included subjective drug effects, cognitive/psychomotor performance, puff topography, vital signs, and whole blood concentrations of Delta 8-THC, Delta 9-THC, and their metabolites. Results: All Delta 8-THC doses and Delta 9-THC produced subjective drug effects that differed from placebo. 20 mg Delta 9-THC elicited stronger ratings of "drug effect" and "unpleasant" than 10 mg Delta 8-THC; no other subjective effects differed between Delta 8-THC and Delta 9-THC. 20 mg Delta 9-THC impaired DRUID performance compared with placebo; no other significant differences were observed between conditions on cognitive/psychomotor measures. Few pharmacodynamic differences were observed between Delta 8-THC doses. Evidence of compensatory puffing emerged, with longer/larger puffs at lower Delta 8-THC doses and placebo. Blood cannabinoid concentrations revealed that Delta 8-THC metabolism differed from Delta 9-THC, with less psychoactive 11-OH metabolite formed after Delta 8-THC exposure. Conclusion: Various doses of vaporized Delta 8-THC elicited comparable psychoactive effects as vaporized Delta 9-THC, which is noteworthy considering Delta 8-THC is less potent and generally perceived as less harmful/intoxicating than Delta 9-THC. The magnitude of effects from cannabinoids is dictated by several factors including dose, route of administration, and, for inhaled methods, puffing behaviors. These data should be considered in future drug policy and public education initiatives.