Relaxant effects and durations of action of formoterol and salmeterol on the isolated human bronchus

Abstract

The objective of this study was to evaluate the potency and efficacy (intrinsic activity) of formoterol and salmeterol and their duration of action in comparison with other β-adrenoceptor agonists in isolated human bronchi. Human bronchi were obtained at thoracotomy from patients with lung cancer. Potency (-log of the concentration of drug inducing 50% of maximal relaxation (log EC50)) and efficacy (maximal effect (Emax), % of response to theophylline 3x10-3 mol·l-1) were determined by analysis of cumulative isometric concentration-response curves to β2-adrenoceptor agonists in bronchial rings at resting tone or contracted maximally with acetylcholine 10-3 mol·l-1 to induce functional antago..