Sulfonamides as Selective Nav1.7 Inhibitors: Optimizing Potency and Pharmacokinetics to Enable in Vivo Target Engagement

Human genetic evidence has identified the voltage-gated sodium channel Na(v)1.7 as an attractive target for the treatment of pain. We initially identified naphthalene sulfonamide 3 as a potent and selective inhibitor of Na(v)1.7. Optimization to reduce biliary clearance by balancing hydrophilicity and hydrophobicity (Log D) while maintaining Na(v)1.7 potency led to the identification of quinazoline 16 (AM-2099). Compound 16 demonstrated a favorable pharmacokinetic profile in rat and dog and demonstrated dose-dependent reduction of histamine-induced scratching bouts in a mouse behavioral model following oral dosing.