Regular use of inhaled albuterol and the allergen-induced late asthmatic response

BACKGROUND: We have recently demonstrated that a 2-week course of inhaled albuterol 200 micrograms four times daily caused a near doubling of the allergen-induced early asthmatic response. We hypothesized that this might extend to the more clinically relevant late asthmatic response. METHODS: We studied 11 patients with atopic asthma who were free from all medications including inhaled beta 2-agonists for more than 4 weeks. We performed a double-blind, random-order, crossover study, comparing the effect of 1-week treatment periods of albuterol 200 micrograms four times daily and placebo 2 puffs four times daily on the early and late asthmatic responses to the same dose of allergen. RESULTS: Regular use of albuterol did not influence the baseline forced expiratory volume in 1 second (FEV1) (3.40 vs 3.42 L, p = 0.84) or the baseline methacholine provocative concentration causing a 20% fall in FEV1 (PC20) (geometric mean, 2.4 mg/ml vs 1.9 mg/ml, p = 0.38). However, all aspects of the allergen-induced asthmatic response were increased. After the 1-week albuterol treatment, the early asthmatic response was slightly greater (21.1% vs 17.9% FEV1 fall, p = 0.26), the late response was greater (23.1% vs 13.2% FEV1 fall, p = 0.0027), and the allergen-induced increase in airway responsiveness (change in log methacholine PC20) was greater (0.37 vs 0.20, p = 0.045). CONCLUSIONS: One week of albuterol treatment (200 micrograms four times daily) increased the late asthmatic response and allergen-induced increase in airway responsiveness. This suggests that the combination of regular use of inhaled beta 2-agonist and allergen exposure may cause more airway inflammation than allergen exposure alone.