Spirometric comparison of carbuterol and isoproterenol aerosol therapy in bronchial asthma. A double blind, matched-pair study of 28 adults and a double blind crossover study of 18 children.

Two adrenergic aerosols were compared in a double blind, matched-pair study of 6 months' duration in 28 adult patients with chronic bronchial asthma, and in a double blind, crossover, short-term study in 18 children with severe asthma. In the adult study, one member of each pair was given either 150 mug of isoproterenol or 200 mug of carbuterol 4 times per day, by inhalation, for 6 months. In the childhood study, 18 children, 6 to 12 years of age, with moderate to severe asthma were studied in a double blind, crossover therapeutic trial in which high or low doses of aerosolized carbuterol or isoproterenol were given 4 times daily for 5 days each. Treatment results were evaluated by measuring forced vital capacity, 1-sec forced expiratory volume, and maximal mid-expiratory flow (FEF25-75%) at regulat intervals before and after administration of the respective test drugs. In the adult study, there was a significant difference between carbuterol and isoproterenol for forced vital capacity (P less than 0.02), for 1-sec forced expiratory volume (P less than 0.02), and for FEF25-75% (P less than 0.01) in favor of carbuterol. In the pediatric study, the difference between carbuterol and isoproterenol was significant (P less than 0.05) only for the FEF25-75% on the fifth day of treatment with the high dose administration of carbuterol. There was no associated toxicity of either drug with respect to electrocardiogram, blood chemistry, or subjective complaints. Tachyphylaxis (tolerance with time) to isoproterenol appeared to develop in one patient.