Emcitate (tiratricol) becomes first approved treatment for MCT8 deficiency
FDA approved tiratricol (Emcitate; Egetis Therapeutics) oral tablets for peripheral thyrotoxicosis in patients with MCT8 deficiency (Allan-Herndon-Dudley syndrome). Tiratricol is a thyroid hormone receptor agonist that bypasses the defective MCT8 transporter, addressing a disorder that previously had no approved US therapy.
Emcitate (tiratricol) ↗ oral tablets for suspension were approved by FDA on 28 September 2026 ↗ for the treatment of peripheral thyrotoxicosis in patients with MCT8 deficiency. This is the first approved therapy for the condition in the United States.
About MCT8 deficiency
MCT8 deficiency (also known as Allan-Herndon-Dudley syndrome ↗) is a rare X-linked disorder caused by mutations in the SLC16A2 gene encoding the monocarboxylate transporter 8 (MCT8). MCT8 normally transports thyroid hormone (T3) across the blood-brain barrier. Affected males develop severe intellectual disability, hypotonia, and characteristic peripheral thyrotoxicosis — with high T3 and low T4 in the blood — due to failure of T3 to enter neurons. Prevalence is estimated at 1 in 70,000 male births.
How tiratricol works
Tiratricol is a thyroid hormone receptor agonist (triac) that does not require MCT8 to enter cells. In peripheral tissues it reduces excessive T3-driven metabolic activity — the cause of cachexia, muscle wasting, and tachycardia in affected patients. Evidence from the TRIAC trial (published in Lancet Child & Adolescent Health) ↗ showed improvements in body weight, heart rate, and biochemical markers vs historical controls.
FDA approval means the agency has determined, based on scientific evidence submitted by the manufacturer, that a drug's benefits outweigh its known risks for a specific indication and patient population. The review process includes evaluation of clinical trial data, manufacturing quality, and proposed labelling. See the FDA drug approval process overview ↗.
Does approval mean the drug is available immediately?
Not always. Commercial launch timelines depend on manufacturing scale-up, pricing, and distribution. REMS-restricted drugs ↗ require prescriber or pharmacy enrolment before the product can be dispensed. Rare disease drugs may also have limited initial supply. Check the manufacturer's website or RxNav ↗ for availability status.