REVIEW Salmeterol's long, lipophilic side chain binds to exosites near beta(2)-receptors in the lungs and on bronchiolar smooth muscle, allowing the active portion of the molecule to remain at the receptor site, continually binding and releasing. Beta(2)-receptor stimulation in the lung causes relaxation of bronchial smooth muscle, bronchodilation, and increased bronchial airflow.
Salpeter SR, Buckley NS, Ormiston TM, Salpeter EE: Meta-analysis: effect of long-acting beta-agonists on severe asthma exacerbations and asthma-related deaths. Ann Intern Med. 2006 Jun 20;144(12):904-12. Epub 2006 Jun 5.