ELN 441958

ELN-441958 is a potent, neutral antagonist of B1 receptor, inhibits the binding of the B1 agonist ligand [3H]DAKD to IMR-90 cells with Ki of 0.26 nM. ELN-441958 is highly selective for B1 over B2 receptors, and >500/ 2000-fold selective for the B1 over μ/δ-opioid receptor.IC50 value: 0.26 nM (Ki)Target: B1 Receptorin vitro: ELN-441958 is a novel small molecule bradykinin B1 receptor antagonist, based on the inhibition of agonist-induced increases in intracellular calcium in native and recombinant cells. ELN-441958 does not inhibit the activation of the human bradykinin B2 receptor at concentrations up to 10 μM, showing that it is highly selective for B1 over B2 receptors. ELN-441958 also displays good selectivity for B1 over other receptors examined in a broad screening panel. It is >500-fold and >2000-fold selective for the B1 receptor over the human μ- and δ-opioid receptor, the most potent off-target activity identified. In IMR-90 cells expressing the native human B1 receptor, ELN-441958 produced a concentration-dependent antagonism of the DAKD-induced calcium mobilization with a KB of 0.12 nM. [1]in vivo: ELN-441958 is essentially completely absorbed and produces high plasma levels after oral administration in rhesus monkeys.ELN-441958 has a moderate clearance and volume of distribution in both species following i.v. administration, consistent with the high metabolic stability in rat, rhesus, and human microsomes. ELN-441958 has high oral exposure and moderate plasma half-lives in rats and rhesus monkeys. The oral availability of ELN441958 in rats was 57%. ELN-441958 dose-dependently reduced carrageenan-induced thermal hyperalgesia in a rhesus monkey tail-withdrawal model, with an ED50 3 mg/kg s.c. [1]