The efficacy of slow versus faster inhalation of cromolyn sodium in protecting against allergen challenge in patients with asthma

Background: Approximately one third of patients with allergy-induced asthma who are treated with aerosolized cromolyn sodium (CS) fail to achieve a full therapeutic effect. This lack of effectiveness could involve nonhomogeneous distribution of drug in the lung as a result of high inspiratory flow rates. Objective: We sought to determine the efficacy of slow versus faster inhalation of CS in protecting against allergen challenge in patients with asthma. Methods: Eight patients with asthma underwent two allergen challenges 30 minutes after pretreatment with CS that was inhaled from a large holding chamber at ~30 L/min or ~70 L/min. Percent decreases in FEV₁ at a common dose of allergen on the two challenge days were compared. Values of skew (an indicator of aerosol distribution homogeneity) obtained from gamma camera lung images after slow and faster inhalation of radiolabeled CS were also compared. Results: Mean (± SD) allergen-induced decrease in FEV₁ was 5.4% ± 4.2% after slow inspiration of CS, which was significantly less than the allergen-induced decrease in FEV₁ after faster inhalation of CS with 12.6% ± 11% (p < 0.05). Mean skew values were also significantly decreased after slow inspiration of CS, and differences in decreases in allergen FEV₁ and skew values for the two breathing maneuvers were significantly correlated. Conclusion: These data indicate that protection against allergen-induced asthma can be optimized by slowly inspiring CS from a large holding chamber compared with faster inhalation of the drug. These results appear to be related to enhanced distribution homogeneity of CS within the lungs.