ELN441958 is a novel, potent and selective bradykinin B1 receptor antagonist with Ki value of 0.26 nM [1].

The bradykinin B1 receptor is a G-protein coupled receptor with principal ligand of bradykinin and plays an important role in chronic pain and inflammation [1].

ELN441958 is a novel, potent and selective bradykinin B1 receptor antagonist. In IMR-90 lung fibroblast cell membranes, ELN441958 competitively inhibited the binding of the agonist [3H]DAKD to the human B1 receptor with Ki value of 0.26 nM. In IMR-90 cells expressing the native human B1 receptor, ELN441958 concentration-dependently antagonized calcium mobilization induced by DAKD with KB value of 0.12 nM. ELN441958 is highly selective for B1 over B2 receptors. ELN441958 failed to inhibit the calcium mobilization induced by B2-receptor agonist BK. ELN441958 also inhibited human μ-, δ-, κ- opioid receptors and muscarinic M1 receptor with Ki values of 0.13, 0.69, 1.5 and 0.37 μM, respectively. ELN441958 is also an agonist at the δ-opioid receptor (EC50 =
0.76 μM) and μ-opioid receptor. In vitro, ELN441958 exhibited good permeability and metabolic stability [1].

In rats and rhesus monkeys, ELN441958 exhibited high oral bioavailability and moderate plasma half-lives. In rhesus monkeys, ELN441958 dose-dependently reduced the thermal hyperalgesia induced by carrageenan with ED50 value of ~3 mg/kg s.c [1].

Reference:
[1]. Hawkinson JE, Szoke BG, Garofalo AW, et al. Pharmacological, pharmacokinetic, and primate analgesic efficacy profile of the novel bradykinin B1 Receptor antagonist ELN441958, J Pharmacol Exp Ther, 2007, 322(2): 619-630.