Salbutamol but not ipratropium abolishes leukotriene D4-induced gas exchange abnormalities in asthma
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Leukotriene D4 (LTD4) is a central mediator in asthma inducing bronchoconstriction and profound disturbances in pulmonary gas exchange in asthmatic subjects. The aim of the study was to compare, for the first time, the influence of the bronchodilators salbutamol (400 μg) and ipratropium (80 μg) on lung function changes induced by inhaled LTD4.
Treatments were evaluated in a randomized, three-period, double-blind, placebo-controlled, cross-over study where spirometric and pulmonary gas exchange indices were followed in 12 subjects with mild asthma before and after LTD4 challenge.
Compared with placebo, salbutamol provided significant protection against the fall in FEV1 (forced expiratory volume in 1 s) after LTD4 challenge. Salbutamol also abolished the LTD4-induced gas exchange disturbances [decreased arterial oxygen tension (PaO2) and increased alveolar–arterial oxygen tension difference (AaPO2)]. Ipratropium provided significant but less marked attenuation of the changes in FEV1 and arterial oxygenation induced by LTD4.
Despite the equal bronchodilatory effects of salbutamol and ipratropium before the challenge with LTD4, salbutamol was superior to ipratropium in preventing spirometric and gas exchange abnormalities. This result indicates a broader action of salbutamol on several of the disturbances that contribute to airway obstruction including, for example, exudation of plasma in the airway mucosa. The clinical implication of this new finding is that in this model of acute asthmatic airway obstruction, salbutamol was more effective than ipratropium.
KeywordsBronchoconstriction Bronchoprovocation Beta2 adrenergic bronchodilator Anti-muscarinic bronchodilator Pulmonary gas exchange.
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