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

The objective of this study was to compare the protective effects of a sing le dose of either cromolyn sodium containing chlorofluorocarbon (CFC) as a propellant or CFC-free cromolyn sodium containing hydrofluoroalkane (HFA) a s a propellant with those of placebo. Seventeen patients with documented ex ercise-induced bronchoconstriction received a single dose of each of the 2 formulations and placebo with washout periods between phases in a randomize d, double-blind, 3-rvay crossover study. Exercise challenge was performed u sing a cycloergometer to achieve greater than or equal to 70% of the predic ted maximum heart rate. The highest of 3 pre-exercise measurements of force d expiratory volume in 1 second (FEV1) was recorded for analysis. Postexerc ise FEV, was measured at 5, 10, 15, 20, 25, and 30 minutes after completion of the challenge. The mean maximum percent decrease in FEV, after exercise and the percent protection index were calculated for each treatment. The m ean maximum percent decrease in postexercise FEV1 was significantly lower ( P < 0.001) in both the CFC and HFA cromolyn sodium groups than in the place bo group (9.9%, 11.7%, and 24.9%, respectively). No significant difference in the maximum percent decrease in postexercise FEV, was noted between the active treatments. The mean percent protection index was 58.7% and 58.0% fo r the CFC and HFA formulations, respectively. Results of this study suggest that HFA-and CFC-containing cromolyn sodium inhalation aerosols are equiva lent in the prevention of exercise-induced bronchoconstriction.