Change in osmolarity of disodium cromoglycate solution and protection against exercise-induced bronchospasm in children with asthma

It has been suggested that osmolarity and/or nebulizer output may affect the protective effects of disodium cromoglycate (DSCG) in asthma. The aim of this study was to evaluate the influence of osmolarity of the DSCG solution on exercise-induced bronchospasm (EIB) in children with bronchial asthma. A jet nebulizer was used for DSCG inhalation in Study 1 and an ultrasonic nebulizer in Study 2. Thirteen asthmatic children (7 males and 6 females, aged 6-14 yrs) were enrolled in Study 1, and nine asthmatic children (5 males and 4 females, aged 9-13 yrs) in Study 2. After pretreatment with saline (control), hypotonic DSCG or isotonic DSCG, children underwent exercise challenge with a cycle ergometer. The percentage fall in forced expiratory volume in one second (FEV1) was measured at 5 and 15 min postexercise. The data were compared by analysis of variance (ANOVA). Both in Study 1 and Study 2, there were no significant differences in minute ventilation volume or maximum heart rate during exercise between the different treatment groups. Both hypotonic and isotonic DSCG significantly reduced the maximum percentage fall in FEV1. There were no significant differences in protective effects between hypotonic and isotonic DSCG in either study. We conclude that the efficacy of hypotonic and isotonic disodium cromoglycate solutions is similar for protection against exercise-induced bronchospasm. Hypotonic disodium cromoglycate seems to be clinically effective for prevention of exercise-induced bronchospasm and treatment of asthmatic children.