Cannabidiol (CBD) content in vaporized cannabis does not prevent tetrahydrocannabinol (THC)-induced impairment of driving and cognition

Abstract

Background The main psychoactive component of cannabis, delta-9-tetrahydrocannabinol (THC), can impair driving performance. Cannabidiol (CBD), a non-intoxicating cannabis component, is thought to mitigate certain adverse effects of THC. It is possible then that cannabis containing equivalent CBD and THC will differentially affect driving and cognition relative to THC-dominant cannabis. Aims The present study investigated and compared the effects of THC-dominant and THC/CBD equivalent cannabis on simulated driving and cognitive performance. Methods In a randomized, double-blind, within-subjects crossover design, healthy volunteers ( n = 14) with a history of light cannabis use attended three outpatient experimental test sessions in which simulated driving and cognitive performance were assessed at two timepoints (20–60 min and 200–240 min) following vaporization of 125 mg THC-dominant (11% THC; < 1% CBD), THC/CBD equivalent (11% THC, 11% CBD), or placebo (< 1% THC/CBD) cannabis. Results/outcomes Both active cannabis types increased lane weaving during a car-following task but had little effect on other driving performance measures. Active cannabis types impaired performance on the Digit Symbol Substitution Task (DSST), Divided Attention Task (DAT) and Paced Auditory Serial Addition Task (PASAT) with impairment on the latter two tasks worse with THC/CBD equivalent cannabis. Subjective drug effects (e.g., “stoned”) and confidence in driving ability did not vary with CBD content. Peak plasma THC concentrations were higher following THC/CBD equivalent cannabis relative to THC-dominant cannabis, suggesting a possible pharmacokinetic interaction. Conclusions/interpretation Cannabis containing equivalent concentrations of CBD and THC appears no less impairing than THC-dominant cannabis, and in some circumstances, CBD may actually exacerbate THC-induced impairment. Electronic supplementary material The online version of this article (10.1007/s00213-019-05246-8) contains supplementary material, which is available to authorized users.

Detection of Δ9 THC in oral fluid following vaporized cannabis with varied cannabidiol (CBD) content: An evaluation of two point‐of‐collection testing devices

“…The current study therefore sought to evaluate the performance of the DW5s and DT5000 POCT devices relative to liquid chromatography−tandem mass spectrometry (LC–MS/MS) confirmatory analysis following controlled laboratory vaporization of THC‐dominant (11% THC, <1% CBD [hereafter ‘THC']); THC/CBD equivalent (11% THC, 11% CBD [hereafter ‘THC/CBD']) and placebo (<1% THC; <1% CBD) cannabis using a double‐blind, within‐subjects, crossover design. This occurred as part of larger study examining the effects of THC‐dominant and THC/CBD‐equivalent cannabis on driving and cognition that has been published elsewhere …”

“…We recently demonstrated impaired driving performance and reduced confidence in driving ability in these same 14 participants at both 30 and 210 minutes following vaporization. 32 However, at 180 minutes, there were no true positive test results in the present study and THC concentrations were typically below the LOQ. Consistent with this, a controlled laboratory study by Ramaekers et al 42 found only a weak relationship between oral fluid THC concentrations and magnitude of impairment on a range of driving-related cognitive tasks following smoked cannabis.…”

“…Consistent with this, it is notable that two participants in the present study had oral fluid THC concentrations >10 ng/mL after vaporizing placebo cannabis containing only minor amounts (< 1%) of THC. Taken together, these data suggest that consumption of high CBD cannabis with very low THC content may still result in a positive DW5s or DT5000 test result, even in the absence of any driving impairment . This raises important questions around the validity of the MDT program and other DUIC programs involving POCT for oral fluid THC.…”

“…This occurred as part of larger study examining the effects of THCdominant and THC/CBD-equivalent cannabis on driving and cognition that has been published elsewhere. 32…”

Vapor inhalation of cannabidiol (CBD) in rats

“…The peak plasma concentrations were also similar to those reported for day old piglets after 1.0 mg/kg CBD, i.v. (Barata et al, 2019) but higher than those reported in humans (~62 ng/mL) using a plant material vaporizer with 11%THC/11%CBD cannabis (Arkell et al, 2019).…”