Tiratricol: First Approval.

Tiratricol (Emcitate®) is an orally bioavailable small molecule being developed by Egetis Therapeutics for the treatment of monocarboxylate transporter 8 (MCT8) deficiency. Tiratricol, an analogue and metabolite of the thyroid hormone triiodothyronine (T3), has thyromimetic effects but differs from T3 in that it can enter cells independent of MCT8. Tiratricol received its first approval on 12 February 2025 in the European Union, for the treatment of peripheral thyrotoxicosis in patients with MCT8 deficiency (Allan-Herndon-Dudley Syndrome), from birth. Tiratricol will be available as 350 µg dispersible tablets. Tiratricol is currently undergoing clinical development for MCT8 deficiency in several other countries including the USA. This article summarizes the milestones in the development of tiratricol leading to this first approval for MCT8 deficiency.