Time course of effect of disodium cromoglycate on exercise-induced asthma.

Exercise tests, consisting of 6 minutes of continuous running, were performed on 10 asthmatic children known to develop exercise-induced bronchoconstriction. Disodium cromoglycate was equally effective in preventing post-exercise bronchoconstriction, whether given 20 minutes before or immediately before exercise. There was a small but significant effect when it was administered at the end of exercise. No placebo effect was noted. Bronchodilatation which occurred during exercise appeared to be enhanced when the drug was given immediately before exercise, but the maximum values of peak expiratory flow rate achieved during exercise were similar in all tests. In practice, no delay is therefore required between administration of disodium cromoglycate and the start of exercise, and the drug can be used in situations that might previously have demanded the use of bronchodilator aerosols for immediate effect.