Aerosol fenoterol by intermittent positive pressure breathing in asthmatic patients

Ten subjects with mild to moderately severe asthma participated in a study of the bronchodilator activity and incidence of side effects of fenoterol aerosol administered by intermittent positive pressure breathing (IPPB). The doses of fenoterol used in the Bird micronebulizer were 0, 0.25 mg, 0.5 mg, 1.0 mg, and 2.5 mg, and these were administered in a randomized, double-blind fashion. The bronchodilator response, assessed by the area under the FEV1 curve, showed mean (+/- SE) values of 1.44 +/- 0.53 1 hr for 0.25 mg of fenoterol to 1.66 +/- 0.56 1 hr for 2.5 mg of fenoterol (p greater than 0.05), longer (p less than 0.01) than the mean placebo response of 0.06 +/- 0.38 1 hr. A dose-dependent increase in tremor was observed for each of the doses of fenoterol. The 0.25-mg dose of fenoterol solution is an appropriate starting dose for the treatment of moderately severe asthma.