Discovery and characterization of pyridazino[4,5-b]indol-4-one derivatives as NaV1.8 inhibitors: A novel approach for targeting chronic pain.

Abstract

Voltage-gated sodium channel Na_V1.8 plays a key role in the development and progression of neuropathic and inflammatory pain, making it an important target for chronic pain treatment. However, the development of drugs targeting Na_V1.8 and other ion channels is still constrained by the low throughput and high cost of conventional patch-clamp techniques. Additionally, existing Na_V1.8 inhibitors suffer from structural uniformity, poor analgesic activity and unfavorable pharmacokinetic properties. In this study, we built a customized virtual screening workflow that combines the structural features of the Na_V1.8 binding pocket with large-scale molecular docking, and applied absolute binding free energy (ABFE) calculations to improve both accuracy and efficiency. Using cell membrane chromatography (CMC) combined with whole-cell patch-clamp assays, we identified compound 12 as a lead compound with potent inhibitory activity against Na_V1.8. Based on compound 12, 17 derivatives were synthesized, and compound 12d was identified as the most promising one after a series of in vitro and in vivo evaluations. This study not only provides a promising lead compound for chronic pain therapy but also offers a paradigm for the precise design and development of drugs targeting other ion channels.