Indacaterol

Indacaterol works by stimulating adrenergic beta-2 receptors in the smooth muscle of the airways. This causes relaxation of the muscle, thereby increasing the diameter of the airways, which become constricted in asthma and COPD. It is also long acting due to its high affinity to the lipid raft domains in the airway membrane so it slowly dissociates from the receptors. Indacaterol also has a high intrinsic efficacy so it is also very rapid acting - onset of action occurs within 5 minutes.

The pharmacological effects of beta2-adrenoceptor agonist drugs, including indacaterol, are at least in part attributable to stimulation of intracellular adenyl cyclase, the enzyme that catalyzes the conversion of adenosine triphosphate (ATP) to cyclic-3’, 5’-adenosine monophosphate (cyclic monophosphate). Increased cyclic AMP levels cause relaxation of bronchial smooth muscle. In vitro studies have shown that indacaterol has more than 24-fold greater agonist activity at beta2-receptors compared to beta1-receptors and 20-fold greater agonist activity compared to beta3-receptors. This selectivity profile is similar to formoterol. The clinical significance of these findings is unknown.