Salbutamol is an agonist of the β2-adrenergic receptor (β2-AR; Kd = 759 nM in a radioligand binding assay using CHO cells expressing the human receptor). It is selective for β2-ARs over β1- and β3-ARs (Kds = 46.8 and 21.9 μM, respectively). Salbutamol (25-50 μg/kg, i.v.) reduces acetylcholine-induced bronchospasm in anesthetized guinea pigs. It also reduces response of bronchial muscle to efferent vagal stimulation in anesthetized cats and dogs when administered at doses ranging from 1 to 2.5 and 10 to 20 μg/kg, respectively. Nebulized salbutamol reduces transpulmonary pressure in recurrent airway obstruction-affected horses (EC50 = 39.7 μg). Formulations containing salbutamol have been used in the treatment of asthma and chronic obstructive pulmonary disease (COPD).