Four months after Vertex Pharmaceuticals Inc.’s U.S. FDA nod for Journavx (suzetrigine) as the first drug targeting NaV1.8 for treating pain, Eli Lilly and Co. is joining the potential competition via a buyout of Siteone Therapeutics Inc., a privately held firm developing small-molecule sodium channel inhibitors, including a phase II-ready NaV1.8 inhibitor.