Vilanterol is a selective long-acting beta2-adrenergic agonist (LABA) used in the treatment of COPD and asthma.

β1-adrenoceptor:6.98±0.03(pEC50), β2-adrenoceptor:10.37±0.05(pEC50), β3-adrenoceptor:7.36±0.03(pEC50)

The selectivity of Vilanterol for β2-AR over the other β-AR receptor subtypes (β2 and β3) is established by testing the ability of Vilanterol to elicit concentration-dependent increases in cAMP in CHO cells expressing human β1-, β2-, and β3-AR. Vilanterol is demonstrated to be highly selective for the β2-AR with at least a 1000-fold selectivity over both β2- and β3-AR subtypes. This analysis results in a low-affinity pKD for [3H]Vilanterol of 9.44±0.07 (n=4) in the presence Gpp(NH)p and a high-affinity pKD of 10.82±0.12 (n=4) and a low-affinity pKD 9.47±0.17 (n=4) in the absence of Gpp(NH)p. In addition, a low-affinity pKD for [3H]Vilanterol of 9.52±0.24 (n=4) in the absence of Gpp(NH)p (37°C) is observed[1]. Vilanterol trifenatate is a novel inhaled long-acting β2-agonist with inherent 24 h activity in vitro in development as a combination with the inhaled corticosteroid fluticasone furoate for both COPD and asthma[2]. Vilanterol is a novel long-acting β2-agonist (LABA) with inherent 24-hour activity for once-daily Clinicalal treatment of chronic obstructive pulmonary disease (COPD) and asthma in combination with the inhaled novel corticosteroid fluticasone furoate, also active for 24 hours[3].

Saturation, association, and dissociation binding studies are performed for [3H]Vilanterol to determine receptor binding kinetics at the β2-AR (equilibrium dissociation constant (KD), total number of receptors (Bmax), association rate (kon), and dissociation rate (koff) are calculated). For saturation binding, membranes (in a volume of 1.4 mL to avoid ligand depletion) are incubated with increasing concentrations of [3H]Vilanterol (~0.01-1.3 nM) for 5 h before filtration. For association binding, membranes are incubated with different concentrations of [3H]Vilanterol (~0.1-1.9 nM) for varying incubation times up to 1 h before filtration. For dissociation binding, membranes are preincubated for 1 h with a fixed concentration of [3H]Vilanterol (~1.1 nM) before dissociation is initiated by a 1:20 dilution in binding buffer (containing 10 μM cold Vilanterol) and then incubated for varying times up to 8 h before filtration. Saturation binding is also completed for [3H]CGP12177 (increasing concentrations of ~0.01-2.8 nM) in the same format as described above for [3H]Vilanterol. To determine the affinity of β2-AR agonists and antagonists, competition binding displacement studies are completed in which membranes are incubated with a fixed concentration of [3H]Vilanterol (~0.2 nM) and increasing concentrations of unlabeled agonist/antagonist for 5 h before filtration. All competition binding displacement studies are completed in the presence of 100 μM Gpp(NH)p to ensure that binding curves are monophasic[1].