Antitussive effect of the leukotriene receptor antagonist zafirlukast in subjects with cough-variant asthma

Cough-variant asthma (CVA) occurs in a subgroup of asthmatics whose sole or predominant respiratory symptom is cough. Although bronchodilatory are often sufficient to treat CVA, refractory, cough may require therapy with inhaled or systemic corticosteroids. In a randomized, double-blind, placebo-controlled, crossover study, we examined the effect of a 14-day course of the leukotriene receptor antagonist zafirlukast on subjective cough score and cough-reflex sensitivity to inhaled capsaicin in eight subjects with CVA to inhaled beta agonists, and in five subjects refractory to inhaled corticosteroids. Seven of eight subjects experienced significant subjective (aid objective improvement in cough after treatment with zafirlukast. Mean SEM) cough score improved from 7.75 +/- 0.56 to 3.25 +/- 0.84 (p = 0.0006). Cough sensitivity, to capsaicin was suppressed by zafirlukast in all subjects. Patients with CVA may represent a distinct Subgroup of asthmatics whose afferent cough receptors within the respiratory, epithelium are hypersensitive relative to those of patients with the typical form of asthma. Zafirlukast appears to be particularly effective in treating CVA by inhibiting the sensitivity of these receptors. Leukotriene receptor antagonists may offer all alternative to corticosteroids for the treatment of CVA refractory to inhaled bronchodilators.