Therapeutic range cromolyn dose-response inhibition and complete obliteration of SO2-induced bronchoconstriction in atopic adolescents

Eight atopic adolescent subjects with exercise-induced bronchospasm were studied to determine whether cromolyn sodium could inhibit or block sulfur dioxide (SO2) -induced bronchoconstriction. Cromolyn or placebo were administered by turboinhaler 20 minutes before 10 minutes of SO2 exposure at 1.0 ppm during continuous moderate exercise on a treadmill. The exercise level that was chosen did not in itself produce bronchoconstriction. The cromolyn doses were 0 (placebo), 20, 40, and 60 mg. Pulmonary functions (FEV1, and total respiratory resistance) were measured before and after drug administration and after exposure. SO2 exposure after placebo produced significant bronchoconstriction. Pretreatment with 20 mg of cromolyn did not change the SO2 response, 40 mg significantly inhibited the response, and 60 mg completely abolished the pulmonary function changes. These results demonstrate for the first time a dose-response inhibition of SO2-induced bronchoconstriction in atopic subjects within a clinically acceptable dosage range and complete obliteration of SO2 sensitivity in this group with 60 mg of cromolyn pretreatment.