Short- and long-term effects of cromolyn sodium on the airway reactivity of asthmatics.

To study the effects of cromolyn sodium on the airway reactivity of asthmatics, we performed a randomized, double-blind, crossover study in which 11 atopic asthmatics inhaled 20 mg of cromolyn sodium or a matching placebo four times daily for 4 wk each, while in their allergy season. Bronchial challenges consisting of either eucapnic hyperventilation with frigid air or methacholine were performed before, in the middle, and at the end of each treatment period. Stimulus-response relationships were assessed with the forced expiratory volume in I sec (FEV1). The level of ventilation (VE) and the provocative dose of methacholine (meth) required to reduce the FEV1 20% from control were recorded as the PD20VE and PD20meth, respectively. There were no significant differences in the baseline FEV1 on any study day. The short-term administration of cromolyn brought about a significant increase In PD20VE prior to both the placebo and active phases of the study. Placebo had no effect on airway reactivity. After 2 wk of cromolyn, PD20VE rose significantly and stayed elevated during the course of the study. Neither the short- nor long-term administration of cromolyn had any effect on the responsiveness to methacholine. These results demonstrated that long-term therapy can attenuate the responsiveness to naturally occurring asthmogenic stimuli even when nonspecific reactivity is unchanged.