Salmeterol and Airway Response to Allergen

Abstract

BACKGROUND: Regular treatment with inhaled salbutamol (seven to 14 days) increases airway responsiveness to allergen.OBJECTIVE: To assess the effect of salmeterol 50 µg twice daily for six days on the early asthmatic response to allergen (PC₁₅).DESIGN: Double-blind, randomized, crossover trial comparing salmeterol with placebo (twice daily over six days) with one week or more washout. Forced expiratory volume in 1 s (FEV₁) and allergen PC₁₅ were measured 36 h after each treatment was discontinued.SETTING: Tertiary care out-patient bronchoprovocation laboratory.SUBJECTS: Fourteen atopic asthmatics well controlled with (n=5) or without (n=9) inhaled corticosteroids. Subjects did not use inhaled beta-agonists for at least two weeks before and during the trial.RESULTS: FEV₁ was slightly but significantly lower 36 h after the last dose of salmeterol versus placebo (3.28±0.83 versus 3.40±0.88 L, P=0.032). Airway responsiveness to allergen increased by about half a doubling concentration (log₁₀ PC₁₅ 2.71±0.61 versus 2.85±0.61, P=0.047).CONCLUSION: A six-day treatment course of salmeterol 50 μg twice daily resulted in a slight decline in FEV₁ and a modest increase in airway response to allergen at 36 h.