Based on the neurophysiology of dyspnoea and the distribution of cannabinoid receptors within the central nervous system, we hypothesize that the unpleasantness of breathlessness will be ameliorated in humans by cannabinoids, without respiratory depression. Five normal and four chronic obstructive pulmonary disease (COPD) subjects entered a double blind, randomized, placebo-controlled crossover study with two test days. Subjects received sublingual cannabis extract or placebo. A maximum of 10.8 mg tetrahydrocannabinol and 10 mg cannabidiol were given. Breathlessness was simulated using fixed carbon dioxide loads. Measurements taken were of breathlessness (visual analogue scale [VAS] and breathlessness descriptors), mood and activation, endtidal carbon dioxide tension and ventilatory...
