| Description: |
Vilanterol trifenatate is a long-acting β2-adrenoceptor (β2-AR) agonist with inherent 24-hour activity. The pEC50s for β2-AR, β1-AR and β3-AR are 10.37, 6.98 and 7.36, respectively. |
| Target: |
pEC50: 10.37±0.05 (β2-adrenoceptor), 6.98±0.03 (β1-adrenoceptor), 7.36±0.03 (β3-adrenoceptor)[1] |
| In Vitro: |
The selectivity of Vilanterol trifenatate 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 clinical treatment of chronic obstructive pulmonary disease (COPD) and asthma in combination with the inhaled novel corticosteroid fluticasone furoate, also active for 24 hours[3]. |
| Kinase Assay: |
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]. |
| References: |
[1]. Slack RJ, et al. In vitro pharmacological characterization of vilanterol, a novel long-acting β2-adrenoceptor agonist with 24-hour duration of action. J Pharmacol Exp Ther. 2013 Jan;344(1):218-30
[2]. Kempsford R, et al. Vilanterol trifenatate, a novel inhaled long-acting beta2 adrenoceptor agonist, is well tolerated in healthy subjects and demonstrates prolonged bronchodilation in subjects with asthma and COPD. Pulm Pharmacol Ther. 2013 Apr;26(2):256-
[3]. Harrell AW, et al. Metabolism and disposition of Vilanterol, a long-acting β(2)-adrenoceptor agonist for inhalation use in humans. Drug Metab Dispos. 2013 Jan;41(1):89-100. |
