Discovery and Optimization of Potent and Subtype-Selective Urea-Derived Na_V1.8 Inhibitors

Inhibitors of voltage-gated sodium channel 1.8 (Na_V1.8) are anticipated to provide opioid-free treatment for acute pain and potentially chronic neuropathic pain. Herein, we report on the discovery of a novel series of Na_V1.8 inhibitors characterized by high selectivity over other sodium channels. Utilizing a pharmacophore model trained on literature data, we identified the initial hit compound 1 through virtual screening. During the hit-to-lead optimization phase, we improved the potency and clearance of the lead compounds. Structural modifications and control of lipophilicity and other physicochemical parameters resulted in a favorable in vitro safety and drug-drug interaction profile for compound 24. Key to optimizing the clearance was the identification of a metabolic hotspot via metabolite identification (MetID) experiments. The lead compound 24 exhibited a long in vivo half-life and high exposure (K _p,uu) in the pain-relevant target tissue (DRG) in rat PK studies. These findings highlight potential of these compounds for further optimization as nonopioid therapeutics.