Rationale: A series of studies conducted approximately 40 years ago demonstrated an acute bronchodilator effect of smoked cannabis in healthy adults and adults with asthma. However, the acute effects of vaporized cannabis on airway function in adults with advanced chronic obstructive pulmonary disease (COPD) remain unknown.
Objectives: To test the hypothesis that inhaled vaporized cannabis would alleviate exertional breathlessness and improve exercise endurance by enhancing static and dynamic airway function in COPD.
Methods: In a randomized controlled trial of 16 adults with advanced COPD (forced expiratory volume in 1 second [FEV1], mean ± SD: 36 ± 11% predicted), we compared the acute effect of 35 mg of inhaled vaporized cannabis (18.2% Δ9-tetrahydrocannabinol, <0.1% cannabidiol) versus 35 mg of a placebo control cannabis (CTRL; 0.33% Δ9-tetrahydrocannabinol, <0.99% cannabidiol) on physiological and perceptual responses during cardiopulmonary cycle endurance exercise testing; spirometry and impulse oscillometry at rest; and cognitive function, psychoactivity, and mood.
Results: Compared with CTRL, cannabis had no effect on breathlessness intensity ratings during exercise at isotime (cannabis, 2.7 ± 1.2 Borg units vs. CTRL, 2.6 ± 1.3 Borg units); exercise endurance time (cannabis, 3.8 ± 1.9 min vs. CTRL, 4.2 ± 1.9 min); cardiac, metabolic, gas exchange, ventilatory, breathing pattern, and/or operating lung volume parameters at rest and during exercise; spirometry and impulse oscillometry-derived pulmonary function test parameters at rest; and cognitive function, psychoactivity, and mood.
Conclusions: Single-dose inhalation of vaporized cannabis had no clinically meaningful positive or negative effect on airway function, exertional breathlessness, and exercise endurance in adults with advanced COPD. Clinical trial registered with www.clinicaltrials.gov (NCT03060993).
Keywords: chronic obstructive pulmonary disease; dyspnea; functional capacity; marijuana.