In vitro and in vivo pharmacological characterization of 5-[(R)-2-(5,6-diethyl-indan-2-ylamino)-1-hydroxy-ethyl]-8-hydroxy-1H-quinolin-2-one (indacaterol), a novel inhaled beta(2) adrenoceptor agonist with a 24-h duration of action.
Here, we describe the preclinical pharmacological profile of 5-[(R)-2-(5,6-diethyl-indan-2-ylamino)-1-hydroxy-ethyl]-8-hydroxy-1H-quinolin-2-one (indacaterol), a novel, chirally pure inhaled beta(2) adrenoceptor agonist, in comparison with marketed drugs. Indacaterol is close to a full agonist at the human beta(2) adrenoceptor (E(max) = 73 +/- 1% of the maximal effect of isoprenaline; pEC(50) = 8.06 +/- 0.02), whereas salmeterol displays only partial efficacy (38 +/- 1%). The functional selectivity profile of indacaterol over beta(1) human adrenoceptors is similar to that of formoterol, whereas its beta(3) adrenoceptor selectivity profile is similar to that of formoterol and salbutamol. In isolated superfused guinea pig trachea, indacaterol has a fast onset of action (30 +/- 4 min) similar to formoterol and salbutamol, and a long duration of action (529 +/- 99 min) comparable with salmeterol. In the conscious guinea pig, when given intratracheally as a dry powder, indacaterol inhibits 5-hydroxytryptamine-induced bronchoconstriction for at least 24 h, whereas salmeterol, formoterol, and salbutamol have durations of action of 12, 4, and 2 h, respectively. When given via nebulization to anesthetized rhesus monkeys, all of the compounds dose-dependently inhibit methacholine-induced bronchoconstriction, although indacaterol produces the most prolonged bronchoprotective effect and induces the lowest increase in heart rate for a similar degree of antibronchoconstrictor activity. In conclusion, the preclinical profile of indacaterol suggests that this compound has a superior duration of action compatible with once-daily dosing in human, together with a fast onset of action and an improved cardiovascular safety profile over marketed inhaled beta(2) adrenoceptor agonists.