Effect of a timed interval between inhalation of beta-agonist and corticosteroid aerosols on the control of chronic asthma.

A randomised double-blind crossover study was undertaken in 25 patients with variable airflow obstruction to assess the benefit of separating the inhalation of beta-agonist aerosols and corticosteroid aerosols by a timed interval of more than five minutes. Twenty-two patients (11 men and 11 women) completed 12 weeks of study; they inhaled 200 micrograms salbutamol followed either immediately or after a timed interval by 100 micrograms beclomethasone dipropionate two to four times daily. Morning and evening peak expiratory flow rates, symptom scores, additional beta-agonist inhaler usage, and subjective responses on a visual-analogue scale were recorded throughout. Results from the two last four-week periods, with and without the interval between drugs, were analysed. No differences were found. It is concluded that the theoretical benefit of delaying corticosteroid inhalation until optimum bronchodilatation has been achieved with a beta-agonist is not demonstrable in outpatient practice.