Salbutamol-d9 is intended for use as an internal standard for the quantification of salbutamol by GC- or LC-MS. 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).1 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.2 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).3 Formulations containing salbutamol have been used in the treatment of asthma and chronic obstructive pulmonary disease (COPD).

References
1. Baker, J.G. The selectivity of β-adrenoceptor antagonists at the human β1, β2 and β3 adrenoceptors. Br. J. Pharmacol. 144(3), 317-322 (2005).
2. Cullum, V.A., Farmer, J.B., Jack, D., et al. Salbutamol: A new, selective β-adrenoceptive receptor stimulant. Br. J. Pharmacol. 35(1), 141-151 (1969).
3. Arroyo, M.G., Cou•til, L.L., Nogradi, N., et al. Efficacy of inhaled levalbuterol compared to albuterol in horses with recurrent airway obstruction. J. Vet. Intern. Med. 30(4), 1333-1337 (2016).