Formoterol-d 3 is deuterium labeled Arformoterol. Arformoterol ((R,R)-Formoterol), the (R,R)-enantiomer of Formoterol, is a long-acting β2-adrenergic receptor (β2-AR) agonist, with a Kd of 2.9 nM. Arformoterol can be used for the research of chronic obstructive pulmonary disease (COPD).