The effect of cannabidiol on simulated car driving performance: A randomised, double-blind, placebo-controlled, crossover, dose-ranging clinical trial protocol.

Objective: Interest in the use of cannabidiol (CBD) is increasing worldwide as its therapeutic effects are established and legal restrictions moderated. Unlike Δ -tetrahydrocannabinol (Δ -THC), CBD does not appear to cause cognitive or psychomotor impairment. However, further assessment of its effects on cognitively demanding day-to-day activities, such as driving, is warranted. Here, we describe a study investigating the effects of CBD on simulated driving and cognitive performance.

Methods: Thirty healthy individuals will be recruited to participate in this randomised, double-blind, placebo-controlled crossover trial. Participants will complete four research sessions each involving two 30-min simulated driving performance tests completed 45 and 210 min following oral ingestion of placebo or 15, 300, or 1,500 mg CBD. Cognitive function and subjective drug effects will be measured, and blood and oral fluid sampled, at regular intervals. Oral fluid drug testing will be performed using the Securetec DrugWipe® 5S and Dräger DrugTest® 5000 devices to determine whether CBD increases the risk of "false-positive" roadside tests to Δ -THC. Noninferiority analyses will test the hypothesis that CBD is no more impairing than placebo.

Conclusion: This study will clarify the risks involved in driving following CBD use and assist in ensuring the safe use of CBD by drivers.