In vitro activity: Indacaterol inhibits cAMP production in Chinese hamster ovary cells stably transfected with human β2 adrenoceptors with pEC50 of 8.06. Indacaterol inhibits electrically induced contraction on the electrically stimulated guinea pig trachea in a concentration-dependent manner with pEC50 of 8.23. Indacaterol induces a concentration-dependent inotropic effect with maximal efficacy of 75% in the isolated guinea pig left atrium. Indacaterol reverses the carbachol-induced contraction in a concentration-dependent manner with IC50 of 37 nM in human small airways. Indacaterol concentration dependently reverses the serotonin-induced contraction with IC50 of 10.5 nM in rat small airways. Indacaterol has the highest intrinsic efficacy of 53% in rat small airways and 73% in human small airways. Indacaterol (10 μM) induces close to full inhibition of the EFS-induced contraction of isolated human bronchi and the effect lasts 12 hours. Indacaterol inhibits the IgE-dependent release of histamine from mast cells with the intrinsic activity (Emax of a long-acting Indacaterol/Emax of Isoprenaline) of 1.03. Indacaterol inihbits cAMP release from human airway smooth muscle with pEC50 of 8.53 and Emax of 48%. Indacaterol appears to have a reduced efficacy compared with the CHO-K1 data in the primary ASM cells.

J Pharmacol Exp Ther. 2006 May;317(2):762-70; J Pharmacol Exp Ther. 2008 Jan;324(1):270-5.