Comparison between ibuterol hydrochloride and terbutaline in asthma.

The bronchodilating effect, circulatory effects, and subjective side effects of ibuterol hydrochloride, the di-isobutyric acid ester of terbutaline, at two dose levels (2 and 4 mg) were compared with those of 5 mg terbutaline sulphate in a double-blind cross-over study on 12 patients with asthma. Both drugs were given by mouth. The 2-mg dose of ibuterol had the same bronchodilating effect during the first three hours as 5 mg terbutaline. The 4-mg dose, however, produced a significantly greater increase in the peak expiratory flow rate between the 30th and 120th minutes than terbutaline. No significant changes in heart rate or pulse amplitude were noted, and there was no difference in the incidence of subjective side effects between ibuterol at either dose level and terbutaline.