Emcitate (tiratricol) for MCT8 deficiency
What the FDA decided
The FDA approved Egetis Therapeutics's NDA for Emcitate (tiratricol) in MCT8 deficiency. Approved September 28, 2026, on its action date, to treat peripheral thyrotoxicosis (the effects of too much thyroid hormone on the body) in adults and children with MCT8 deficiency, also called Allan-Herndon-Dudley syndrome. It is the first FDA-approved treatment for the disease. Emcitate is a tablet dispersed in water and given by mouth or feeding tube, with the dose raised about every 2 weeks against blood T3, which has to be measured by LC-MS/MS because the drug makes standard T3 tests read falsely high. In the randomized withdrawal study, T3 rose in all 8 patients switched to placebo, more than in any of the 7 who stayed on the drug; it has not been shown to improve brain development. The label carries a boxed warning against use for weight loss, and the most common side effects were diarrhea, vomiting, rash and excessive sweating. Egetis expects it to be available within 8 to 10 weeks through its Egetis RareLink program and received a Rare Pediatric Disease Priority Review Voucher.
Who this decision matters to
MCT8 deficiency, also called Allan-Herndon-Dudley syndrome, is a rare X-linked disorder in which thyroid hormone cannot enter the brain because the transporter that carries it, MCT8, is missing or broken. The result is a brain starved of thyroid hormone during development while the rest of the body is flooded with it. Boys have severe motor and intellectual disability alongside low weight, a fast heart rate and poor muscle mass. On September 28, 2026 the FDA approved Emcitate (tiratricol), the first treatment for the disease, to treat the thyroid hormone excess in the body.
Prevalence: fewer than 1 in 1,000,000 people; a few hundred published cases worldwide, almost all boys (the largest study gathered 151 patients from 22 countries). See our full MCT8 Deficiency page for current treatments, recruiting trials, and community resources.
About the drug
Emcitate: thyroid hormone analog that enters cells without the MCT8 transporter, activating thyroid hormone receptors while suppressing the body's own T3 production. Our full Emcitate profile covers how it works, side effects in plain language, and its trial history.
Where MCT8 Deficiency treatment stands today
Read our full MCT8 Deficiency treatment summary
On September 28, 2026 the FDA approved Emcitate (tiratricol), the first treatment for MCT8 deficiency in the US, for peripheral thyrotoxicosis in adults and children with the disease. Tiratricol is a thyroid hormone analog that reaches cells without needing MCT8 and lowers blood T3 into the normal range, which reverses the body-side thyrotoxicosis.
The evidence behind it comes from a single-arm trial of 46 patients (Triac Trial I), a small randomized withdrawal study (ReTRIACt), and long-term follow-up; a trial of early treatment in boys under 30 months (Triac Trial II) did not show a statistically significant benefit on gross motor development compared with historical controls, so the drug should be understood as treating the body's thyroid hormone excess rather than reversing the brain's deficit. Egetis expects it to be available 8 to 10 weeks after approval through its Egetis RareLink program (1-844-434-3847), and the dose has to be adjusted against T3 measured by a specialized test (LC-MS/MS), because the drug makes standard T3 tests read falsely high.
Before approval, US patients with a confirmed genetic diagnosis were treated through the manufacturer's expanded access program (NCT05911399) at 17 hospital sites across 15 states. Separately, a physician-sponsored expanded access protocol at the University of Miami (NCT04143295) treats affected male fetuses before birth in families with a known SLC16A2 variant.
Care otherwise centers on nutrition, physical therapy, seizure control and managing spasticity, and a pediatric endocrinologist together with a neurologist should coordinate it. The MCT8-AHDS Foundation connects families with clinicians who have experience of the condition.
The MCT8 Deficiency page has every treatment and trial →Meanwhile, 2 MCT8 Deficiency trials are recruiting
Whatever the FDA decides here, research on MCT8 Deficiency does not stop. A few currently enrolling studies, US sites first:
You'll hear about future FDA decisions and new recruiting trials for MCT8 Deficiency. Unsubscribe anytime.
Our coverage
Frequently asked questions
Has the FDA decided on Emcitate?
The FDA has already decided. It approved the application.
Details: the outcome and what it means are at the top of this page.
Source: FDA press release
What was Emcitate approved for?
The FDA approved Egetis Therapeutics's NDA for Emcitate in MCT8 deficiency.
What to know: Approved September 28, 2026, on its action date, to treat peripheral thyrotoxicosis (the effects of too much thyroid hormone on the body) in adults and children with MCT8 deficiency, also called Allan-Herndon-Dudley syndrome. It is the first FDA-approved treatment for the disease. Emcitate is a tablet dispersed in water and given by mouth or feeding tube, with the dose raised about every 2 weeks against blood T3, which has to be measured by LC-MS/MS because the drug makes standard T3 tests read falsely high. In the randomized withdrawal study, T3 rose in all 8 patients switched to placebo, more than in any of the 7 who stayed on the drug; it has not been shown to improve brain development. The label carries a boxed warning against use for weight loss, and the most common side effects were diarrhea, vomiting, rash and excessive sweating. Egetis expects it to be available within 8 to 10 weeks through its Egetis RareLink program and received a Rare Pediatric Disease Priority Review Voucher.
How it works: Thyroid hormone analog that enters cells without the MCT8 transporter, activating thyroid hormone receptors while suppressing the body's own T3 production.
More: the Emcitate drug page explains it in plain language.
Is there already an FDA-approved treatment for MCT8 Deficiency?
Yes. Trial Friend's drug list includes 1 FDA-approved drug for MCT8 Deficiency.
Approved: Emcitate (tiratricol).
Check: the MCT8 Deficiency page also searches FDA drug labels for approved treatments.
What did the Emcitate trials show?
The US label rests on 2 studies . Triac Trial I (NCT02060474), the label's Study 2, was a single-arm, open-label Phase 2 trial of 46 male patients aged 10 months to 66.8 years in 8 European countries and South Africa, published in The Lancet Diabetes & Endocrinology in 2019 . After 12 months, mean total T3 fell from 323.4 to 118.3 ng/dL (4.97 to 1.82 nmol/L), heart rate fell by 8.9 beats per minute and systolic blood pressure by 4.1 mmHg; there was no placebo group. ReTRIACt (NCT05579327), the label's Study 1, enrolled 20 male patients aged 5 to 31; the 15 who reached a stable dose were randomized to continue tiratricol or switch to placebo for 30 days.
More: the Emcitate drug page has the full trial history and sources.
What are the side effects of Emcitate?
The US label lists diarrhea, vomiting, rash and excessive sweating as the most common side effects, each affecting 5% or more of patients. In the 20-patient randomized withdrawal study, vomiting and rash each affected 10% and sweating 5%; in the 46-patient Triac Trial I, diarrhea affected 13%, vomiting 11%, rash 9% and sweating 7% . Most side effects are what too much thyroid hormone feels like: in Triac Trial I, heart rate rose temporarily in 35% of patients and systolic blood pressure in 26% during dose titration, and 30% had at least 1 side effect of that kind (diarrhea, sweating, irritability, insomnia or nightmares), mostly while the dose was being raised . The label carries a boxed warning that Emcitate, like all thyroid hormones, must not be used to treat obesity or for weight loss, and it is contraindicated in primary hyperthyroidism.
Most common: diarrhea, vomiting, rash, excessive sweating (hyperhidrosis).
More: the Emcitate drug page lists the warnings in full.
How much will Emcitate cost?
Trial Friend does not list a price for Emcitate. What you pay depends on your insurance and on help from the drugmaker or a charity fund.
Help paying: drugmaker programs and charity funds usually open at launch.
Find help: the patient assistance finder lists programs by insurance type.
What happens after the Emcitate decision?
This page updates with the outcome the day it is announced.
If approved: getting the drug still takes time. Specialty pharmacy setup, insurance review and patient assistance often take weeks. Our guide covers what families can do on day 1.
If not approved: a complete response letter means the FDA declined the application in its current form. Many are about manufacturing or how data were presented, and companies often resubmit.
Where this date comes from
The FDA does not publish PDUFA dates; companies disclose them. This one comes from FDA press release. Dates can move, and the FDA can act early or late. This page rechecks against our calendar, which is re-verified daily.