Xenon shares plunge 23% after voluntary hold on psychiatry trials, despite filing NDA for epilepsy drug

Xenon Pharmaceuticals announced that its lead asset azetukalner (AZK) has been submitted to the FDA as a new drug application for focal onset seizures.

At the same time, the company disclosed a voluntary pause on its psychiatric studies of the same drug after several patients experienced psychosis, prompting a hold on those trials.

The news sent Xenon’s shares down about 23% in pre‑market trading, falling to $44.27 from $57.35 the previous close, despite the CEO’s optimism about the epilepsy opportunity valued at roughly $2 billion.

Analysts noted that while psychosis is a serious adverse event, similar issues have been seen with other psychiatric medicines and do not necessarily block the epilepsy program’s progress.