Effects of long-acting bronchodilators and placebo on histamine-induced asthma symptoms and mild bronchusobstruction

STUDY OBJECTIVE: Accurate perception of airway caliber remains an important issue in asthma management. The way bronchodilation is perceived is partly related to the perception of the efficacy of bronchodilators in relieving complaints. In the present study, we compared the effects of salmeterol, formoterol and placebo on relief of histamine-induced asthma symptoms and mild bronchusobstruction. METHODS: In this randomized controlled, double blind study, 30 asthmatics were challenged with histamine until forced expiratory volume in 1s (FEV(1)) fell with > or =20%. Subjects received salmeterol, formoterol or placebo after the histamine provocation. Pulmonary function (FEV(1)) and asthma symptoms (Asthma Symptom Checklist, Borg Dyspnea Scale) were assessed 5 and 20 min later. RESULTS: FEV(1) improved significantly more in the salmeterol and formoterol group than in the placebo group (P<0.001, P<0.001 and P<0.05, respectively). Salmeterol and formoterol were not different with regard to the pulmonary function recovery. No significant differences were found between the effects of salmeterol, formoterol and placebo on any of the symptom responses at the different time points. CONCLUSIONS: We conclude that after a histamine-induced mild bronchusobstruction, a similar asthma symptom recovery occurred when inhaling salmeterol, formoterol or placebo, despite better recovery of pulmonary function in the active drug conditions.