NCIt definition : A short-acting, beta-adrenergic receptor agonist with bronchodilator activity. Pirbuterol
selectively binds to beta-2 adrenergic receptors in bronchial smooth muscle, thereby
activating intracellular adenyl cyclase, an enzyme that catalyzes the conversion of
adenosine triphosphate (ATP) to cyclic-3',5'-adenosine monophosphate (cAMP). Increased
cAMP levels cause relaxation of bronchial smooth muscle, relieve bronchospasms, improve
mucociliary clearance and inhibit the release of mediators of immediate hypersensitivity
from cells, especially from mast cells.;