Acute Effects of Smoked and Vaporized Cannabis in Healthy Adults Who Infrequently Use Cannabis

IMPORTANCE Vaporization is an increasingly popular method for cannabis administration,and policy changes have increased adult access to cannabis drastically.Controlled examinations of cannabis vaporization among adults with infrequent current cannabis use patterns(>30 day ssince lastuse)are needed.

OBJECTIVE: To evaluate the acute dose effects of smoked and vaporized cannabis using controlled administration methods.

DESIGN,SETTING,AND PARTICIPANTS This within-participant,double-blind,crossover study was conducted from June 2016 to January 2017 at the Behavioral Pharmacology Research Unit, Johns Hopkins University School of Medicine, and included 17 healthy adults. Six smoked and vaporized outpatient experimental sessions (1-week wash out between sessions)were completed in clusters (order counterbalanced across participants);dose order was randomized within each cluster.

INTERVENTIONS Cannabis containing Δ9-tetrahydrocannabinol (THC) doses of 0mg, 10mg, and 25mg was vaporized and smoked by each participant.

MAIN OUTCOMES AND MEASURES Change from baseline scores for subjective drug effects, cognitive and psycho-motor performance,vital signs,and blood THC concentration.

RESULTS The sample included 17 healthy adults (mean[SD]age, 27.3 [5.7] years; 9 men and 8 women)with no cannabis use in the prior month (mean[SD]days since last cannabis use, 398 [437] days). Inhalation of cannabis containing 10 mg of THC produced discriminative drug effects(mean [SD] ratings on a 100-point visual analog scale,smoked:46 [26]; vaporized:69 [26]) and modest impairment of cognitive functioning.The 25-mg dose produced significant drugeffects(mean[SD] ratings,smoked:66[29];vaporized:78[24]),increased incidence of adverse effects, and pronounced impairment of cognitive and psychomotorability (eg, significant decreased task performance compared with placebo in vaporized conditions). Vaporized cannabis resulted in qualitatively stronger drug effects for most pharmacodynamic outcomes and higher peak concentrations of THC in blood, compared with equal doses of smoked cannabis(25-mg dose: smoked,10.2ng/mL;vaporized,14.4ng/mL). Blood THC concentrations and heart rate peaked within 30minutes after cannabis administration and returned to baseline within 3 to 4 hours. Several subjective drug effects and observed cognitive and psychomotor impairments persisted for up to 6 hours on average.

CONCLUSIONS AND RELEVANCE Vaporized and smoked cannabis produced dose-orderly drug effects,which were stronger when vaporized.These data can inform regulatory and clinical decisions surrounding the use of cannabis among adults with little or no prior cannabis exposure.