The effects of acute and sustained cannabidiol dosing for seven days on the haemodynamics in healthy men: A randomised controlled trial

Background In vivo studies show that cannabidiol (CBD) acutely reduces blood pressure (BP) in men. The aim of this study was to assess the effects of repeated CBD dosing on haemodynamics. Methods Twenty-six healthy males were given CBD (600 mg) or placebo orally for seven days in a randomised, placebo-controlled, double-blind, parallel study (n = 13/group). Cardiovascular parameters were assessed at rest and in response to isometric exercise after acute and repeated dosing using Finometer (R), Vicorder (R) and Duplex ultrasound. Results Compared to placebo, CBD significantly reduced resting mean arterial pressure (P = .04, two-way ANOVA, mean difference (MD) -2 mmHg, 95% CI -3.6 to -0.3) after acute dosing, but not after repeated dosing. In response to stress, volunteers who had taken CBD had lower systolic BP after acute (P = .001, two-way ANOVA, MD -6 mmHg, 95% CI -10 to -1) and repeated (P = .02, two-way ANOVA, MD -5.7 mmHg, 95% CI -10 to -1) dosing. Seven days of CBD increased internal carotid artery diameter (MD +0.55 mm, P = .01). Within the CBD group, repeated dosing reduced arterial stiffness by day 7 (pulse wave velocity; MD -0.44 m/s, P = .05) and improved endothelial function (flow mediation dilatation, MD +3.5%, P = .02, n = 6 per group), compared to day 1. Conclusion CBD reduces BP at rest after a single dose but the effect is lost after seven days of treatment (tolerance); however, BP reduction during stress persists. The reduction in arterial stiffness and improvements in endothelial function after repeated CBD dosing are findings that warrant further investigation in populations with vascular diseases.