Vilanterol is a long-acting beta-2 adrenergic agonist, with bronchodilator activity. Upon administration, vilanterol stimulates beta-2 adrenergic receptors in the lungs, thereby activating the enzyme adenylate cyclase that catalyzes the conversion of adenosine triphosphate (ATP) to cyclic-3′,5′-adenosine monophosphate (cAMP). Increased cAMP concentrations relax bronchial smooth muscle, relieve bronchospasms, and reduce inflammatory cell mediator release, especially from mast cells