Comparison of the effects of inhaled calcium antagonist verapamil, sodium cromoglycate and ipratropium bromide on exercise-induced bronchoconstriction in children with asthma
Fifteen children with exercise-induced asthma (EIA) participated in a double-blind trial comparing the protective effects of inhaled sodium cromoglycate (20 mg/2ml), ipratropium bromide (500 μg/2ml) and verapamil (5 mg/2ml). Saline was used as control. There was no significant difference in base line pulmonary function before and after the administration of each agent. After exercise the maximal percentage fall in the forced expiratory volume in 1 s (FEV-1) (means and SD) were 40.9±17.2 after inhalation of saline, 15.3±11.7 after sodium cromoglycate, 36.2±21.4 after verapamil and 21.7±17.7 after ipratropium bromide. The inhibitory effects of sodium cromoglycate and ipratropium bromide were significant whereas verapamil failed to produce any effect. To see if a double dose of verapamil is more effective, nine different children with EIA were provoked by the same standardized treadmill running after giving a placebo (4 ml saline) and after verapamil (10 mg in 4 ml). Despite the double dose, again verapamil was ineffective even though the protection index doubled that obtained with the lower dose. The results suggest that the calcium antagonist (verapamil) had almost no effect on the prevention of EIA in the children studied.