It is known that cromolyn sodium and nedocromil sodium share similar antiallergic properties. This study examined whether nedocromil sodium, a pyranoquinoline dicarboxylic acid, could inhibit sulfur dioxide (SO2) bronchoconstriction in a dose-dependent manner in 10 men with mild asthma. Previous studies have shown that cromolyn sodium produces such inhibition in allergic monkeys and asthmatic subjects. Subjects in this double-blind, placebo-controlled study were nonsmoking men between the ages of 23 and 40 years (mean age, 30.7 years). The study took place over 5 days within a 3-week period. On the first of 5 days, each subject had a history taken and physical examination, SO2 baseline test, laboratory testing, and a methacholine dose-response test. On each of 4 test days, the subjects received pretreatment with either placebo or a 2, 4, or 8 mg dose of nedocromil sodium in a randomized, double-blind sequence, followed after 30 minutes by an SO2 dose-response test. Results showed that maximum bronchoconstriction response to SO2 was significantly attenuated (p < 0.01) by all three doses of nedocromil sodium, with small differences noted between dose levels. We concluded that nedocromil sodium inhibited SO2-induced bronchospasm at dose levels as low as 2 mg.
