Sodium cromoglycate and ipratropium bromide in exercise-induced asthma.

Abstract

In 13 patients with extrinsic asthma the effects of placebo, sodium cromoglycate, ipratropium bromide and ipratropium bromide plus sodium cromoglycate were studied in a random double-blind fashion to assess their inhibitory action in exercise-induced asthma (EIA). Exercise testing consisted of steady state running on an inclined treadmill for up to 8 min. In 8 of the 13 patients studied the baseline ratio of expiratory flow at 50% vital capacity (VC) breathing He-O2 (.ovrhdot.V50He) to .ovrhdot.V50air was over 1.20 and they were called responders; the remaining 5 patients were called non-responders. There was a significantly lower baseline maximum mid-expiratory flow rate (MMEF) in non-responders (P < 0.02) as compared to responders but no difference in forced expiratory volume in 1 (FEV1) or forced vital capacity (FVC). Sodium cromoglycate (P < 0.02), ipratropium bromide (P < 0.01) and ipratropium bromide plus sodium cromoglycate (P < 0.01) all significantly inhibited the percentage fall in FEV1 after exercise in the responders. Ipratropium bromide had no preventive action in non-responders, unlike sodium cromoglycate (P < 0.05) and ipratropium bromide plus sodium cromoglycate (P < 0.02). Mediator release apparently is an important factor in development of EIA in most extrinsic asthmatics; cholinergic mechanisms are relevant only in those patients in whome the main site of airflow obstruction is in the large central airways.