Xenon Pharmaceuticals paused enrollment in Phase 2 trials of its KV7 potassium channel opener azetukalner for major depressive disorder and bipolar disorder after reports of neuropsychiatric adverse events. Patients already enrolled will remain on study, and the ongoing recruitment pause is intended to allow safety review and potential dosing modifications. Shares moved sharply on the announcement as investors weighed the risk profile in depression while the company simultaneously pursued FDA review for focal onset seizures using the same asset. The episode highlights how class- and mechanism-based safety expectations can diverge once broader populations are exposed in later-stage psychiatry programs.