Relation between efficacy of sodium cromoglycate and baseline lung function in exercise- and hyperventilation-induced asthma.

The protective effect of sodium cromoglycate (SCG) against exercise- and hyperventilation-induced asthma with respect to basal lung function was investigated in young asthmatics. The subjects performed standardized exercise or isocapnic hyperventilation challenge tests breathing cold dry air; in each case the effect of SCG was compared with that of a placebo in a double-blind fashion. With exercise as the challenge in 24 subjects, there was a strong positive correlation between the protective effect of SCG and the basal level of lung function. Using hyperventilation as the challenge in 11 subjects, there was no such correlation, but excluding two known placebo responders, there was a negative correlation between the protective effect of SCG and basal lung function. There findings suggest that exercise and hyperventilation operate differently in inducing asthma.