Salmeterol and Airway Response to Allergen

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 (PC 15 ). 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 (FEV 1 ) and allergen PC 15 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: FEV 1 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 (log 10 PC 15 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 FEV 1 and a modest increase in airway response to allergen at 36 h.