Vilanterol, also known as GW-642444, is a long-acting beta-2 agonist. It selectively induces cAMP accumulation in CHO cells expressing the β2-AR over the β1- and β3-ARs (EC50s = 0.4, 398, and 794 nM for the human receptors, respectively). Vilanterol inhibits contractions induced by electrical stimulation in isolated superfused guinea pig trachea strips. It inhibits bronchospasms induced by histamine. Formulations containing vilanterol, in combination with fluticasone, have been used in the treatment of chronic obstructive pulmonary disease (COPD) and asthma.