Inhaled ethanol potentiates the cough response to capsaicin in patients with airway sensory hyperreactivity

A suggested explanation for airway symptoms induced by chemicals and scents is sensory hyperreactivity (SHR) of airway mucosal nerves. Patients with SHR have increased cough sensitivity to inhaled capsaicin, mediated by transient receptor potential (TRP) ion channels. In animal experiments, some TRP receptors are potentiated by ethanol, which is why in this study, the aim was to evaluate whether a pre-inhalation of ethanol could influence the capsaicin cough response in patients with SHR. Fifteen patients with SHR and 15 healthy controls were provoked on three occasions with two concentrations of inhaled capsaicin. Before each capsaicin provocation, a pre-inhalation of saline or one of two concentrations of ethanol was given in a double-blind, randomized fashion. The participants reacted in a dose-dependent way with cough on the capsaicin inhalations. Among the patients, but not in the control group, pre-inhalation of ethanol increased the cough response dose-dependently. The results suggest that the pathophysiology of SHR is related to airway mucosal TRP receptors in the sensory nerves. In scented products, the combination of ethanol as a solvent and perfume may augment an airway reaction in sensitive individuals.