Double-blind, placebo-controlled study of single doses of chlorofluorocarbon (CFC) and CFC-Free cromolyn sodium for exercise-induced bronchoconstriction

Abstract

The objective of this study was to compare the protective effects of a single dose of either cromolyn sodium containing chlorofluorocarbon (CFC) as a propellant or CFC-free cromolyn sodium containing hydrofluoroalkane (HFA) as a propellant with those of placebo. Seventeen patients with documented exercise-induced bronchoconstriction received a single dose of each of the 2 formulations and placebo with washout periods between phases in a randomized, double-blind, 3-way crossover study. Exercise challenge was performed using a cycloergometer to achieve ≥70% of the predicted maximum heart rate. The highest of 3 pre-exercise measurements of forced expiratory volume in 1 second (FEV 1) was recorded for analysis. Postexercise FEV 1 was measured at 5, 10, 15, 20, 25, and 30 minutes after completion of the challenge. The mean maximum percent decrease in FEV 1 after exercise and the percent protection index were calculated for each treatment. The mean maximum percent decrease in postexercise FEV 1 was significantly lower ( P < 0.001) in both the CFC and HFA cromolyn sodium groups than in the placebo group (9.9%, 11.7%, and 24.9%, respectively). No significant difference in the maximum percent decrease in postexercise FEV 1 was noted betwwen the active treatments. The mean percent protection index was 58.7% and 58.0% for the CFC and HFA formulations, respectively. Results of this study suggest that HFA- and CFC-containing cromolyn sodium inhalation aerosols are equivalent in the prevention of exercise-induced bronchoconstriction.