Site of bronchodilatation with inhaled ipratropium bromide and fenoterol in normal subjects.

To assess the effectiveness and site of action of bronchodilatation with an inhaled anticholinergic bronchodilator, ipratropium bromide, and a beta adrenergic agonist, fenoterol, we measured the density dependence of maximal flow and the density dependence of pulmonary resistance using a digital computerized averaging circuit. Eight normal subjects were studied on two separate days, before and after the bronchodilators were administered in a double blind manner. Both drugs resulted in significant and equivalent bronchodilatation. However, there were no significant changes in the density dependence of maximal flow or pulmonary resistance with either agent. These results in normal subjects, therefore, do not support the hypothesis of a preferential site of action of inhaled anticholinergic agents and beta-adrenergic agents.