Preventive effect of 2 and 10 mg of sodium cromoglycate on exercise-induced bronchoconstriction

Abstract

This double-blind, randomised and cross-over study was designed to compare the preventive effect against exercise-induced bronchoconstriction (EIB), defined as the percentage decrease in FEV₁≥15% after 6 min of exercise, of 2 mg and 10 mg of sodium cromoglycate (SCG), administered through a metered dose inhaler via spacer, in asthmatic children. Each of the 30 subject (age 11.6 ± 3.2 years) was tested on five occasions. For inclusion, EIB in test1 was required. In tests 2 to 5, all subjects inhaled 2 mg or 10 mg of SCG 20 min and 120 min before exercise in a randomised order. In order to assess excretion of eosinophil protein X (EPX) accompanying EIB, urine samples were collected before and after exercise. The mean percentage fall in FEV₁ (±SD) in test 1 was 26.8 ± 9.8%. Inhalation of 2 mg and 10 mg of SCG 20 min before exercise provided a significant preventive effect in 83% and 77% and inhalation 120 min before exercise provided a preventive effect in 63% and 70%, respectively (n=30). Variance analysis did not reveal a statistically different absolute fall in FEV₁ after exercise when both doses (120 min before exercise) were compared (P=0.356). In an unselected subgroup of 12 children, urinary EPX increased after the challenge without SCG premedication (test 1) (mean change: +48.7 μg/mmol creatinine, P=0.034), whereas no significant increase was found in case of SCG premedication (mean change in μg/mmol creatinine): 2 mg/20 min: +12.1; 2 mg/120 min: +8.5; 10 mg/20 min: −10.4 and 10 mg/120 min: −23.5; P > 0.1).

Conclusion Administration of 10 mg of sodium cromoglycate is no more effective in preventing exercise-induced bronchoconstriction than 2 mg regardless of whether the medication is given 20 or 120 min before exercise. The preventive effect of sodium cromoglycate on exercise-induced bronchoconstriction in asthmatic children is associated with the inhibition of urinary eosinophil protein X excretion.