Effect of salmeterol is independent of previously inhaled salbutamol: a clinical controlled study

Abstract

The objective of this study was to examine the bronchodilating effect of an inhaled long acting beta2-agonist (salmeterol) after a high dose of an inhaled short acting beta2-agonist (salbutamol) in asthma patients. We used a randomized double-blind, placebo-controlled, crossover design, studying seven subjects with moderate asthma, treated with inhaled steroids and highly reversible to salbutamol and salmeterol. 1.5 h after salmeterol inhalation, the mean difference in FEV1 between salbutamol and placebo pretreatment days was 6.31% and ranged from 0.02 to 1.05%, 2.5-10.5 h after salmeterol inhalation. We concluded that the effect measured as the duration of bronchodilation of salmeterol is not decreased by previously inhaled salbutamol. We only found a trend toward an additive effect of combining salbutamol and salmeterol, probably because the high dose of salbutamol did not give room for further improvement in FEV1. In accordance with other clinical studies we were unable to demonstrate any clinical implications of the salmeterol partial beta2-antagonism known from animal and in vitro studies.