Aerosol formulations of terbutaline and isoproterenol in theophylline-stabilized asthmatic patients.
A metered-dose aerosol formulation of terbutaline sulfate (Brethaire), 0.400 mg four times daily, was compared with an identical formulation of isoproterenol sulfate, 0.150 mg four times daily, in a parallel, double-blind, clinical study completed by 40 adult patients with asthma. All patients had been stabilized on theophylline (serum levels of 10 to 20 micrograms/ml). The effectiveness of isoproterenol peaked between 5 and 15 minutes after administration. The effectiveness of terbutaline peaked between 5 and 120 minutes after administration. In each of five visits spaced over a three-month period, patients receiving terbutaline showed a longer duration of bronchodilatory effect than those receiving isoproterenol, with the greatest difference occurring at 60 and 120 minutes after drug administration.