Salmeterol is an effective long-acting beta(2)-agonist
bronchodilator, able to inhibit, as a single dose, asthmatic responses induced by several stimuli including
allergen, and the subsequent increase in sputum
eosinophilia. Aim of the present study was to investigate whether these effects of
salmeterol persisted after 1 week of continuous treatment, or whether a loss of the bronchoprotective effects of
salmeterol can occur over time. We investigated in a cross-over double blind placebo-controlled study, the protective effect of 1 week treatment with
salmeterol on
allergen-induced early and late responses and the associated airway
inflammation in 15 atopic asthmatic subjects. Eosinophil percentage and
Eosinophil Cationic Protein (ECP) concentration in peripheral blood and in hypertonic saline induced sputum were measured at baseline and 24 h after
allergen inhalation.
Salmeterol partially inhibited early asthmatic response, but it did not inhibit late asthmatic response in comparison with placebo.
Salmeterol did not inhibit also the increase in sputum eosinophils percentage 24 h after
allergen inhalation (E%, median: 22.7 and 15%, after placebo and after
salmeterol respectively, p=n.s. between two post-
allergen sputum samples). Also, the increase in blood eosinophils and both sputum and serum ECP at 24 h after
allergen challenge was not affected by
salmeterol pre-treatment. In conclusion, 1 week treatment with
salmeterol causes a loss of its protective effect on
allergen-induced airway bronchoconstriction, and does not prevent the subsequent increase in sputum and serum eosinophilic markers.