Relief of dyspnoea by β2-agonists after methacholine-induced bronchoconstriction

AbstractVirtually all asthma patients use bronchodilators. Formoterol and salbutamol have a rapid onset of bronchodilating effect, whereas salmeterol acts slower. We studied the onset of improvement of dyspnoea sensation after inhalation with these bronchodilators and placebo to reverse a methacholine-induced bronchoconstriction as a model for an acute asthma attack.Seventeen patients with asthma completed this randomised, double-blind, crossover, double-dummy study. On 4 test days, forced expiratory volume in 1s (FEV1) and Borg score were recorded and patients were challenged with methacholine until FEV1 fell with ⩾30% of baseline value. Thereafter, formoterol 12μg via Turbuhaler®, salbutamol 50μg via Turbuhaler®, salmeterol 50μg via Diskhaler™, or placebo was inhaled. FEV1 and Borg scores were assessed during the following 60min.The first sensed improvement of Borg score was significantly (P