NCIt definition : A highly selective, long-acting beta-2 adrenergic agonist with bronchodilatory activity.
Salmeterol's benzene moiety resembles the structure of catecholamines, and occupies
the active site of beta-2 adrenergic receptor, while the long, lipophilic side chain
of salmeterol, binds to the so called 'exosite' near the beta-2 adrenergic receptors.
The binding at the exosite allows the active portion of the molecule to remain at
the receptor site and continually engage and disengage with the receptor, therefore
providing a long duration of action. This agent stimulates intracellular adenyl cyclase
to catalyze the conversion of adenosine triphosphate to cyclic-3',5'-adenosine monophosphate
(cAMP). Increased cAMP levels result in relaxation of bronchiolar smooth muscle, bronchodilation
and increased bronchial airflow.;