NCIt definition : A short-acting sympathomimetic beta-2 adrenergic receptor agonist with bronchodilator
activity. Levalbuterol binds to beta-2 adrenergic receptors in bronchial smooth muscle
and activates intracellular adenyl cyclase, an enzyme that catalyzes the conversion
of adenosine triphosphate (ATP) to cyclic-3',5'-adenosine monophosphate (cAMP). Increased
cAMP levels lead to the activation of protein kinase A, which inhibits the phosphorylation
of myosin and lowers intracellular ionic calcium concentrations, resulting in relaxation
of bronchial smooth muscles. The increased cAMP concentrations also inhibit the release
of inflammatory mediators, especially from mast cells.;