Inhibition of allergen‐induced asthma by three forms of sodium cromoglycate

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Abstract
The effect of 3 forms of sodium cromoglycate (SCG), 20 mg, on allergen-induced early asthmatic responses was examined in 10 stable asthmatic patients. Dose response allergen inhalation tests were performed on 5 occasions at intervals of from 1-2 wk to determine the provocation concentration producing a 20% reduction (PC20 allergen) in FEV1 [forced expiratory volume in 1 s]. Placebo was given before the first and the last tests to determine the reproducibility of responses to allergen over the study period; reduced responsiveness was observed in 8 of the 10 subjects. Major changes in levels of specific serum antibodies of the IgE and IgG classes did not serve to explain the changes in bronchial responses although there was a trend which suggested IgG-related desensitization. The changes in bronchial responses and antibody levels illustrate the requirement for tests of reproducibility of responses by the use of placebo controls at the beginning and end of a series of allergen inhalation challenges. SCG as a micronized powder with lactose, as micropellets without lactose or as an aerosol, were inhaled double-blind, in random order, 5 min before the additional 3 allergen inhalation tests. PC20 allergen was reduced following SCG in 7 subjects; the differences were statistically significant for the group. There was no observed difference in efficacy between the different forms of SCG. The efficacy of SCG could not be related to age, atopic status, the initial level of allergen-specific IgE antibody, baseline FEV1, level of bronchial responsiveness to inhaled histamine or an effect of SCG on responsiveness to histamine.