Cromolyn sodium inhibits the increased responsiveness to methacholine that follows ultrasonically nebulized water challenge in patients with asthma

Abstract

We have previously reported that airway responsiveness to inhaled methacholine in subjects with asthma is increased 40 to 60 minutes after challenge with ultrasonically nebulized water. This study reveals that increased responsiveness to methacholine is abolished by administration of cromolyn sodium before the water challenge. The mean dose of methacholine (95% confidence limits) inducing a 20% fall in FEV1 (PD20) was 1.10 mumol (0.43 to 2.80). The PD20 after water challenge was 0.42 mumol (0.17 to 1.01) that was significantly lower (p less than 0.005) than that observed for the initial challenge. Administration of cromolyn before the water challenge abolished this increased responsiveness to methacholine. The mean PD20 was 1.32 mumol (0.47 to 3.68) that was not significantly different from that measured for the initial methacholine challenge. Methacholine responsiveness was unchanged when challenge was performed 40 to 60 minutes after cromolyn alone or after methacholine itself. We conclude that cromolyn abolishes the increased responsiveness to methacholine and probably does so by inhibiting the release of mediators.