['chronic obstructive pulmonary disease (copd)', 'breathlessness', 'exercise intolerance']
['cannabis', 'placebo']

        Inclusion Criteria:

          -  GOLD stage III or IV COPD (i.e., post-β2-agonist FEV1 of 50% predicted or less)

          -  Self-reported cigarette smoking history ≥10 pack yrs

          -  Currently taking long-acting beta-2 agonists and long-acting antimuscarinic agents
             (LABA/LAMAs) with or without an inhaled corticosteroid

          -  Willing to abstain from cannabis smoking for ≥15 days prior to study participation (if
             applicable)

          -  Willing to abstain from non-study related cannabis smoking throughout the study period
             (if applicable)

          -  No change in medication dosage or frequency of administration, with no exacerbations
             or hospitalizations in the preceding 4 weeks

        Exclusion Criteria:

          -  Presence of active and/or uncontrolled cardiopulmonary and/or musculoskeletal disease
             other than COPD that could contribute to breathlessness and exercise intolerance

          -  Hepatic or renal impairment

          -  Psychiatric history (other than depression and/or anxiety)

          -  History of epilepsy or convulsions;

          -  Lung cancer

          -  History of sensitivity to cannabis

          -  Use of levodopa, sildenafil and/or fentanyl

          -  Use of ketoconazole

          -  Use of regular high dose opioids (i.e., 30 mg of oral morphine equivalents/day)

          -  Known or suspected history of addiction/substance abuse based on CAGE-AID and SISAP
             scores (*note, patients may be recruited if they have a history of smoking cannabis)

          -  Positive urine toxicology for cannabinoids on screening

          -  Positive pregnancy urine test

          -  Subject cannot arrange to be accompanied home by a family member and/or friend during
             each treatment visit.
      