The effect of inhaled fenoterol, administered during the late asthmatic reaction to house dust mite (Dermatophagoides pteronyssinus).

A double-blind, placebo-controlled crossover study was set up to investigate the effect of fenoterol (400 micrograms) during the late asthmatic reaction (LAR). Twenty young subjects with asthma (mean age, 11.8 years; range, 8.3 to 20.6 years) were selected on the basis that they developed an LAR after bronchial challenge with Dermatophagoides pteronyssinus. After the LAR occurred, a placebo and fenoterol were administered blindly by a metered-dose inhaler, with an interval of 15 minutes and in alternating, random sequence. At the start of the study, that is, a documented LAR, the two groups of subjects had the same severity of LAR, as expressed by the fall of the FEV1 (mean, -34.5% versus -33.5%). The mean FEV1 of the 10 patients who received placebo first changed only -1.1% (+/- 5.0), whereas after fenoterol, The FEV1 increased by 20.7% (+/- 10.8). In the 10 patients receiving fenoterol first, the mean FEV1 rose by 18.8% (+/- 8.0), whereas the placebo inhalation resulted in a supplementary increase of 3.1% (+/- 7.0). The paired Student's t test between these differences (placebo versus fenoterol) was highly significant (p less than 0.001). Although it was demonstrated in some studies that beta-agonists did not prevent the LAR, the present study demonstrates that the administration of fenoterol can reverse the FEV1 significantly, although it was not reversed completely, during an allergen-induced LAR.