Effect of Ipratropium Bromide on Airway Cough Sensitivity to Inhaled Capsaicin in Patients with Asthma and Sinobronchial Syndrome

抄録

To evaluate the influence of parasympathetic nerve innervation on airway cough sensitivity, we examined the effect of a non-selective muscarinic receptor antagonist, ipratropium bromide (IB), on cough sensitivity to inhaled capsaicin, a stimulant to C-fiber endings, in 12 patients with asthma, 14 patients with sinobronchial syndrome (SBS) and 14 normal subjects in a randomized, placebocontrolled, single blinded, cross-over manner. Progressively increasing concentrations of capsaicin solution were inhaled for 15 seconds by mouth tidal breathing at one minute intervals from a Bennett Twin nebulizer until five or more coughs were elicited, before and 30 minutes after inhalation of 40μg of IB or placebo (freon gas) through a metered-dose inhaler. The capsaicin cough threshold was defined as the lowest concentration of capsaicin solution that produced five or more coughs. The capsaicin cough threshold was significantly increased by both IB and placebo in patients with asthma and SBS but not in normal subjects. The increment of the cough threshold defined as the logarithmic value of the cough threshold after treatment divided by the initial cough threshold was significantly greater with IB than that with placebo only in patients with SBS. These results suggest that airway cogh sensitivity is augmented through parasympathetic nerve innervation in patients with SBS but not asthmatic or normal subjects.