Effects of Divided Doses of a Bronchodilator Aerosol and the Intervening Time Interval on the Forced Expiration

Abstract

Twelve patients with bronchial asthma participated in a blind, randomized, crossover study comparing the effects of 500 μg terbutaline in one inhalation, 125 μg in four inhalations taken in rapid succession, and 125 μg in four inhalations taken with an intervening time interval of 30 min. There were no significant differences between the three modes of inhalation of 500 μg terbutaline in any of the spirometric variables, i.e., 1-second forced expiratory volume, forced vital capacity, and maximal airflows when 50 and 75% of the forced vital capacity was exhaled from the total lung capacity. However, there were neither any significant differences between the levels of bronchodilation reached after administration of 500 μg and 2 or 3 × 125 μg terbutaline with an intervening time interval of 30 min. The time interval between the divided doses was possibly too long to achieve maximum accumulated effect of the four divided doses

Bronchodilator responsiveness in children with asthma is not influenced by spacer device selection

“…Third, our study did not assess whether the effect of salbutamol inhaled at one time point is equivalent to that inhaled cumulatively over 90 min. However, previous studies have shown the dose effect of short‐acting bronchodilators to be independent of the time course of inhalation and we expect the effect of the higher doses of salbutamol (eg, 800 and 1200 μg) inhaled cumulatively to be very similar to that of 1200 μg inhaled in quick succession.…”