Effects of ketotifen on cholinergic induced airway obstruction

By repeated inhalant carbachol provocation tests on 13 normal and 13 asthmatic subjects, we investigated the effect of ketotifen (as compared with placebo) on the cholinergic responsiveness of the airways. In normal subjects, ketotifen reduced the slope of the linear regression lines, calculated from the airway resistance vs. the intra-pulmonary deposited amount of carbachol (reactivity). By adding a single dose of 80 mg of propranolol the bronchial reactivity was increased. Neither placebo nor ketotifen pretreatment altered the response to propranolol. In asthmatic subjects, the reactivity of the airways to carbachol was reduced after 7 days of ketotifen treatment. Propranolol increased the pre-challenge airway resistance values, and ketotifen did not reduce this bronchoconstrictive action. We could not observe any influence of ketotifen on the potentiation of the carbachol-induced bronchoconstriction. We conclude that ketotifen on the potentiation of the carbachol-induced bronchoconstriction. We conclude that ketotifen reduces the bronchial reactivity as assessed by carbachol inhalation in normal and in asthmatic subjects.