A comparison of ketotifen with clemastine, ipratropium bromide and sodium cromoglycate in exercise‐induced asthma

Abstract

Exercise-induced asthma (EIA) was provoked by a standardized treadmill running for 8 min in 7 atopic adult asthmatics. The tests were performed using a double-dummy technique after placebo, oral ketotifen, inhaled clemastine, ipratropium bromide and sodium cromoglycate (SCG), in a random single blind-fashion on different days. The mean post-exercise percentage fall in forced expiratory volume in 1 s (FEV1) was 47 (SE 6.95), 39 (SE 8.35), 27 (SE 7.17), 23 (SE 7.69) and 7.0 (SE 4.62)%, respectively. There was significantly less mean bronchoconstriction with SCG (P < 0.01), ipratropium bromide and clemastine (P < 0.05) but not with ketotifen. Six of 7 individual patients had significant protection of EIA with sodium cromoglycate, 4 with ipratropium bromide, 3 with clemastine but only 1 with ketotifen. Ipratropium bromide and clemastine were bronchodilators at rest, wheras SCG and ketotifen were not. Despite its claims to work as a mast cell stabilizing drug, ketotifen in a single dose does not have an effect similar to sodium cromoglycate in EIA, nor does it compare with inhaled clemastine or ipratropium bromide.