Discovery of a Novel Class of State-Dependent Na1.7 Inhibitors for the Treatment of Neuropathic Pain.

The discovery of a novel class of state-dependent voltage-gated sodium channel (Na)1.7 inhibitors is described. By the modification of amide or urethane bond in Na1.7 blocker III, structure-activity relationship studies that led to the identification of novel Na1.7 inhibitor 2i (DS01171986) were performed. Compound 2i exhibited state-dependent inhibition of Na1.7 without Na1.1, Na1.5 or human ether-a-go-go related gene (hERG) liabilities at concentrations up to 100 μM. Further biological profiling successfully revealed that 2i possessed potent analgesic properties in a murine model of neuropathic pain (ED: 3.4 mg/kg) with an excellent central nervous system (CNS) safety margin (> 600 fold).