An inhaled glucocorticoid does not prevent tolerance to the bronchoprotective effect of a long-acting inhaled beta 2-agonist
Abstract
There is increasing evidence for the development of tolerance to the protective effects of inhaled beta 2-agonists against bronchoconstrictor stimuli. Animal studies have suggested that glucocorticoids protect against the down-regulation of beta 2-receptors after chronic exposure to beta 2-agonists. In a double-blind placebo-controlled crossover study in 12 patients with mild asthma, we investigated the effect of inhaled budesonide or identical placebo on the protection conferred by albuterol (200 micrograms) against methacholine-induced bronchoconstriction before and after treatment with the long-acting beta 2-agonist salmeterol. Patients were randomized to be treated for 3 wk with inhaled budesonide (800 micrograms twice a day) or placebo; salmeterol (50 micrograms twice a day) was added during the third week. Airway responsiveness to methacholine was measured 15 min after albuterol, both before and exactly 12 h [corrected] after the last salmeterol dose. Mean FEV1 increased significantly after 2 wk of budesonide (p < 0.05) and increased further after salmeterol (p < 0.05) compared with placebo. After 2 wk, the bronchoprotective effect of albuterol against methacholine was significantly greater with budesonide than with place...Continue Reading
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