A study of isoetharine mesylate in patients with chronic bronchial asthma

We performed a double-blind, random crossover study to investigate the respiratory effects of a single dose isoetharine mesylate (IM), administered by a metered aerosol canister in 19 subjects with mild, stable asthma. In addition, we studied the influence of the dose (number of actuations) and the mode of administration (delay between actuations) on these respiratory effects. The protocol consisted of a screening day and four test days: (1) one inhalation IM (2) two inhalations IM (3) one inhalation placebo (P), and (4) two inhalations P. In addition, the first nine asthmatics paused one minute between inhalations whereas the last ten paused five minutes between inhalations. Lung function was assessed using maximal and partial expiratory flow volume curves. Measurements were taken prior to aerosol delivery and for six hours after aerosol. Significant differences between IM and P were seen for up to two hours. The maximum effect was observed at 15 minutes, corresponding to a 23% and 25% increase in FEV1 from baseline with one and two puffs, respectively (P less than .001). The differences between one and two actuations were, in general, not significant. No significant differences were observed between individuals who waited one versus five minutes between inhalations. We conclude that IM aerosol results in significant improvement compared with placebo for two hours. Differences between one and two inhalations and the interval between two inhalations did not, in general, lead to enhanced effectiveness of this drug in the group of asthmatics studied.