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.