First FDA-Approved Treatment for MCT8 Peripheral Thyrotoxicosis

Emcitate (tiratricol) is a thyroid hormone receptor agonist supplied as 350 mcg tablets for oral suspension, dispersed in room-temperature drinking water and given by mouth or enteral feeding tube. On 28 September 2026, the U.S. Food and Drug Administration approved Emcitate to treat peripheral thyrotoxicosis in adults and pediatric patients with MCT8 deficiency (Allan-Herndon-Dudley syndrome) — Novel Drug Approvals 2026 #45; first FDA-approved treatment for this indication. The application holder is Rare Thyroid Therapeutics International AB (NDA 220963 on Drugs@FDA). The FDA press release names Egetis Therapeutics US Inc. as the US company. On 12 February 2025, the European Commission granted a marketing authorisation valid throughout the EU for Emcitate to treat peripheral thyrotoxicosis in MCT8 deficiency from birth (EMA EPAR EMEA/H/C/005220; MA EU/1/24/1897/001). EMA lists the EC decision as 12 February 2025; some company materials cite 13 February — this article uses the EMA date. The EU medicine is a hybrid of the French reference product Téatrois (same active substance; different tablet form).

Distinct path — not this medicine: Supportive developmental care, tube feeding, seizure care, or cardiac monitoring alone are not this Emcitate tablet for oral suspension. Emcitate is not recommended for primary hypothyroidism (USPI). It is contraindicated in primary hyperthyroidism (USPI) and, on the EU SmPC, for hyperthyroidism for reasons other than MCT8 deficiency. Boxed warning (USPI): not for treatment of obesity or weight loss. Compounded tiratricol / Triac products made outside Egetis / Rare Thyroid Therapeutics are not labelled Emcitate. In the United States, Emcitate is the labelled medicine for peripheral thyrotoxicosis in MCT8 deficiency (FDA, 28 Sep 2026). In the European Union, it is also Emcitate (EMEA/H/C/005220).

US application holder (NDA 220963): Rare Thyroid Therapeutics International AB. US company named in the FDA press release: Egetis Therapeutics US Inc. EU marketing authorisation holder: Rare Thyroid Therapeutics International AB, Klara Norra Kyrkogata 26, 111 22 Stockholm, Sweden (Egetis Therapeutics AB group).

Where this is taking place

United States (labelled commercial supply): FDA approved Emcitate on 28 September 2026 for peripheral thyrotoxicosis in adults and pediatric patients with MCT8 deficiency. Form: tablets for oral suspension; taken once daily as a liquid suspension by mouth or feeding tube (FDA press; USPI also allows the total daily dose once daily or in 2–3 divided doses). Company (Egetis approval release 28 Sep 2026) expects commercial availability in the US in eight to ten weeks post approval. Patient support: Egetis RareLink™ in partnership with PANTHERx® Rare for medication access, education, and care coordination — phone 1-844-4EGETIS (1-844-434-3847) (company-labelled; not an FDA commercial guarantee). The US expanded access programme (NCT05911399), which supplied tiratricol to some patients before approval, is now listed on ClinicalTrials.gov as “Approved for marketing” and is no longer listed as available (status verified October 2026; lead sponsor Rare Thyroid Therapeutics International AB; collaborators Egetis Therapeutics AB and AnovoRx). It should not be counted on as a way to get the medicine while waiting for commercial stock. The US route is now a prescription. AnovoRx, the specialty partner for the earlier expanded access programme, is not named here as the commercial distributor.

European Union (labelled): EC-authorised Emcitate for peripheral thyrotoxicosis in MCT8 deficiency from birth; prescription only; start and supervise under a clinician experienced in rare genetic disorders. Germany: company confirms commercial availability from 1 May 2025. G-BA orphan benefit assessment procedure 2025-05-01-D-1191 completed with resolution 16 October 2025 — hint for a non-quantifiable additional benefit (English courtesy translation of the G-BA justification). Other EU member-state pricing and reimbursement dossiers and timelines vary — authorised is not the same as funded in every country.

Canada / other regulators: Emcitate authorisation not confirmed on sources used here. Do not import on your own. An EU-labelled box or a US-labelled bottle is not a foreign Product Monograph.

Named research programmes (not, by themselves, a way to get the medicine):

• Triac Trial I — NCT02060474 (completed) — Erasmus Medical Center–led Phase 2 open-label; 46 males; mean serum T3 4.97 → 1.82 nmol/L after 12 months (EMA overview / Lancet Diabetes & Endocrinology 2019).
• Triac Trial II — NCT02396459 (active but no longer taking new patients) — young boys ≤30 months; company/pipeline: primary neurodevelopmental endpoints not met; secondary T3 reduction supportive.
• ReTRIACt — NCT05579327 (completed) — Phase 3 randomised withdrawal cited on FDA press among efficacy studies; company topline 14 Nov 2025: T3 rate-of-change primary p=0.034 (placebo vs continued tiratricol).
• EMC Cohort — van Geest et al., J Clin Endocrinol Metab 2022 (real-world long-term; up to ~6 years; n=67 in company/journal reports).
• EMC Survival — van der Most et al., ETA 2024 abstract / company 21 Aug 2024: HR 0.28 (95% CI 0.09–0.91) for all-cause mortality vs untreated in a retrospective international cohort (n=228) — abstract / company statement, not a USPI claim.
• US expanded access programme — NCT05911399 (now listed as Approved for marketing; no longer listed as available).

In practice, start with a paediatric endocrinology / genetics / rare-thyroid team. They can confirm SLC16A2 / MCT8 genetics and arrange the legal route for your country.

Approval matrix

Access by country

• United States (labelled): Ask a paediatric endocrinology / genetics / rare-thyroid clinician about labelled Emcitate for peripheral thyrotoxicosis. Path: confirm MCT8 deficiency → specialist prescription under the USPI → Egetis RareLink™ (1-844-4EGETIS) / PANTHERx® Rare for access support when commercial stock is available (company expects 8–10 weeks from 28 Sep 2026). The expanded access programme (NCT05911399) is no longer listed as available. If commercial stock has not reached you yet, ask the prescribing clinic what to do in the meantime. No list price or copay dollars in this article.

• European Union (labelled): Ask a clinician experienced in rare genetic / MCT8 care about labelled Emcitate for peripheral thyrotoxicosis. Path: confirm MCT8 deficiency → pregnancy exclusion when relevant → individual T3-guided titration (SmPC) → national pharmacy / reimbursement rules. Germany has a commercial launch from 1 May 2025. Other member states: confirm local launch and funding with the treating centre. Authorized is not funded.

• Canada: Emcitate authorisation not confirmed. Ask the Canadian clinic what legal paths exist in Canada (including whether any Special Access Programme or other named-patient rule applies) while there is no Canadian Product Monograph.

• United Kingdom / Australia / Japan / Switzerland / other countries: Confirm your local regulator’s current status with the treating centre. Company managed-access statements are not a home licence. Do not import on your own.

• If your regulator has not authorised it: do not import on your own. Ask the local clinician about documented special-access / named-patient rules, referral to a centre in a labelled country, documented expanded access, or waiting for a home decision.

Who is eligible

This is a peripheral thyrotoxicosis conversation — not a claim that tiratricol reverses all neurodevelopmental disability from brain hypothyroidism.

United States (company USPI — Initial U.S. Approval: 2026; Revised 09/2026):

• Indication: Treatment of peripheral thyrotoxicosis in adults and pediatric patients with MCT8 deficiency (Allan-Herndon-Dudley syndrome).
• Limitation of use: Not recommended for treatment of primary hypothyroidism.
• Form: 350 mcg tablets for oral suspension (functional scoring; can be halved). Disperse in room-temperature drinking water only; do not swallow whole, chew, or crush; oral or enteral feeding tube.
• Boxed warning: Thyroid hormones, including Emcitate, should not be used for treatment of obesity or for weight loss.
• Contraindication: Primary hyperthyroidism.
• Other thyroid medicines: Not recommended with other thyroid medications (USPI §7.1; FDA press).
• Common adverse reactions (≥5% on USPI Highlights): diarrhea, vomiting, rash, hyperhidrosis.
• Lab honesty: Prefer LC-MS/MS for total T3; tiratricol cross-reacts on immunoassay and can overestimate T3. An FDA-authorized LC-MS/MS test for total T3 is not currently available; available LC-MS/MS tests may vary in accuracy (USPI).
• FDA press efficacy statement: two studies including RCT NCT05579327 and a longer-term open-label study; reductions in excess circulating thyroid hormone; improvements in cardiovascular/metabolic markers (e.g. SBP, heart rate); patients ranging from infants through adults.

European Union (SmPC 4.1 / 4.2 / 4.3):

• Indication: Treatment of peripheral thyrotoxicosis in patients with MCT8 deficiency (Allan-Herndon-Dudley syndrome), from birth.
• Form: 350 microgram dispersible tablets (scored; can be halved). Disperse in water; oral syringe or gastroenteral feeding tube.
• Contraindications: Hypersensitivity to tiratricol or excipients; hyperthyroidism for reasons other than MCT8 deficiency; pregnancy.
• Common adverse reactions (SmPC): hyperhidrosis (7%), diarrhoea (6%), irritability / anxiety / nightmares (2% each) — often at start or dose increase; usually transient.
• Supervision: Start and monitor under a physician experienced in rare genetic disorders such as MCT8 deficiency.

United States expanded access (NCT05911399): ClinicalTrials.gov now lists this programme as “Approved for marketing”, so its entry rules no longer describe a route for new patients. In the United States, eligibility now follows the prescribing information above.

Not claimed on the sources checked for this article:

• Health Canada marketing authorisation.
• Treating Emcitate as a cure for all MCT8 neurodevelopmental disability (Triac Trial II primary neurodevelopmental endpoints not met per the company; USPI indication is peripheral thyrotoxicosis only).
• Walk-in enrolment into completed / active but no longer taking new patients research records.

How it is taken

United States (company USPI §2):

The prescribing clinician uses the current USPI for down-titration on thyrotoxicosis symptoms, missed-dose rules, feeding-tube French-size limits, and pediatric vision assessment notes.

European Union (SmPC): body weight ≥10 kg — start 350 µg daily, increase by 350 µg about every 2 weeks; body weight <10 kg — start 175 µg (half tablet) daily, increase by 175 µg about every 2 weeks. Titrate toward serum T3 below the midpoint of the age-normal range; give total daily dose in 1–3 divided doses. SmPC lists weight-based maximum µg/kg/day ceilings — the prescribing clinician uses the current SmPC. Prefer LC/MS/MS for T3.

Safety (what the label puts first)

USPI (company; Revised 09/2026):

• Boxed warning: Not for treatment of obesity or for weight loss.
• Thyrotoxicosis (Warnings): Signs and symptoms (e.g. increased heart rate, elevated blood pressure, diarrhea, hyperhidrosis, irritability, insomnia, nightmares) can occur during initiation and titration — monitor and adjust dose per USPI.
• Laboratory interference: Tiratricol cross-reacts with T3 immunoassays — use LC-MS/MS.
• Contraindication: Primary hyperthyroidism.
• Most common adverse reactions (≥5%): diarrhea, vomiting, rash, hyperhidrosis.
• Report suspected adverse reactions to Egetis Therapeutics US Inc. at 1-844-4EGETIS (1-844-434-3847) or FDA at 1-800-FDA-1088 / www.fda.gov/medwatch.

EU SmPC: contraindications include other-cause hyperthyroidism and pregnancy; common ARs as above. The treating clinician uses the current SmPC / USPI for the home label.

What the pivotal study showed (ReTRIACt / Triac Trial I)

FDA press (28 Sep 2026): Effectiveness evaluated in two clinical studies in patients ranging from infants to adults, including international multi-center randomised placebo-controlled trial NCT05579327 and a longer-term open-label study. Across both, Emcitate was associated with reductions in excess circulating thyroid hormone and improvements in cardiovascular/metabolic markers (e.g. systolic blood pressure, heart rate).

ReTRIACt — NCT05579327 (completed; company topline 14 Nov 2025; cited on FDA press):

• Double-blind randomised withdrawal Phase 3 in males ≥4 years on stable tiratricol.
• PE1 T3 rate-of-change: ratio placebo/tiratricol 1.494 (95% CI 1.035–2.155); p=0.034. All 8 placebo patients had larger T3 rises than the 7 continuing tiratricol.

Triac Trial I — NCT02060474 (EMA overview + Lancet Diabetes & Endocrinology 2019; completed):

• Design: international, single-arm, open-label Phase 2 (no placebo comparator).
• Population: 46 children and adults with MCT8 deficiency.
• Result used at EU authorisation: mean serum T3 4.97 → 1.82 nmol/L after 12 months; supportive signals on heart rate, blood pressure, premature atrial contractions (EMA overview).

Triac Trial II — NCT02396459 (active but no longer taking new patients; company/pipeline):

• Young boys ≤30 months (n=22 actual enrollment on CT.gov).
• Primary GMFM-88 / BSID-III gross-motor endpoints not met; durable T3 reduction as a secondary result.

EMC Cohort (van Geest et al., JCEM 2022): long-term real-world tiratricol use (company: 67 patients, up to 6 years) with sustained T3 and peripheral markers.

EMC Survival (van der Most et al., ETA 2024 abstract / company 21 Aug 2024): retrospective n=228; treated vs untreated all-cause mortality HR 0.28 (95% CI 0.09–0.91) — observational; not a USPI claim.

The labelled indication is peripheral thyrotoxicosis. Peripheral T3 control is not the same as reversing all neurodevelopmental disability from brain hypothyroidism. Completed trials are not taking new patients.

How to talk to a doctor

Bring this page and ask a paediatric endocrinology / genetics / rare-thyroid clinician:

1. “We have genetically confirmed MCT8 deficiency. Is labelled US Emcitate (or labelled EU Emcitate where launched) a fit for peripheral thyrotoxicosis?”
2. “How will we titrate dose and measure T3 (LC-MS/MS vs immunoassay)?”
3. “What are the pregnancy / hypermetabolic-symptom monitoring steps, and how do the USPI boxed warning and primary-hyperthyroidism contraindication apply?”
4. If in the US: “How do we reach Egetis RareLink (1-844-4EGETIS), and when will commercial stock be available through RareLink and PANTHERx Rare?”
5. If outside a labelled country: “Has our regulator authorised Emcitate, or what legal special-access options exist?”

Research and regulatory team

• US application holder: Rare Thyroid Therapeutics International AB (NDA 220963, approved 28 Sep 2026; Drugs@FDA). The FDA press release names Egetis Therapeutics US Inc. as the US company.
• US patient support (company): Egetis RareLink™ with PANTHERx® Rare — 1-844-4EGETIS (1-844-434-3847); also USPI adverse-reaction reporting line.
• EU MAH: Rare Thyroid Therapeutics International AB, Stockholm (EMA EPAR / SmPC).
• Group / commercial: Egetis Therapeutics AB (publ), Nasdaq Stockholm: EGTX (company releases).
• EU research leadership cited on company launch: Professor Edward Visser and team, Erasmus University Medical Center, Rotterdam.
• Triac Trial I sponsor (CT.gov): Erasmus Medical Center (NCT02060474).
• Triac Trial II / ReTRIACt / US expanded access programme sponsor (ClinicalTrials.gov): Rare Thyroid Therapeutics International AB; Egetis listed as collaborator where applicable.
• US expanded access programme collaborators (ClinicalTrials.gov): AnovoRx; Egetis Therapeutics AB (publ). The programme is now listed as Approved for marketing. AnovoRx is not named here as the commercial distributor.
• Company general contact (egetis.com): +46 8 679 72 10; info@egetis.com — company switchboard.

Names and roles above are limited to what appears on the primary sources cited. Contacts not listed on those sources are omitted.

Canada: authorisation not confirmed

Emcitate / tiratricol authorisation is not confirmed at Health Canada on the sources used for this article. Emcitate is FDA-approved, but Health Canada approval is not confirmed. Ask a Canadian specialist what legal Special Access Programme or named-patient options exist in Canada. An EU-labelled box or a US-labelled bottle is not a Canadian Product Monograph. Do not import on your own.

Bottom line

FDA approved Emcitate on 28 September 2026 (Novel #45) as the first US treatment for peripheral thyrotoxicosis in adults and pediatric patients with MCT8 deficiency. EU authorisation since 12 February 2025 and Germany’s commercial launch remain true. Company expects US commercial availability in 8–10 weeks with RareLink / PANTHERx support. Drugs@FDA lists the application (NDA 220963); the DailyMed listing is not yet indexed. Health Canada is not confirmed. Peripheral T3 control is not a cure for brain under-development. Authorized is not funded. Not medical advice.

Primary sources

• FDA press: FDA Approves First Treatment for MCT8 Deficiency — https://www.fda.gov/news-events/press-announcements/fda-approves-first-treatment-mct8-deficiency (For Immediate Release: September 28, 2026)
• FDA Novel Drug Approvals for 2026 — https://www.fda.gov/drugs/novel-drug-approvals-fda/novel-drug-approvals-2026 (Emcitate / tiratricol / 9/28/2026 — Novel #45)
• Company USPI Emcitate (tiratricol) tablets for oral suspension — Revised 09/2026; Initial U.S. Approval: 2026 (company-hosted copy); NDC 87216-0100-1 on company HOW SUPPLIED. FDA label on Drugs@FDA (NDA 220963)
• Egetis Therapeutics approval release 28 Sep 2026 — https://www.egetis.com/news/egetis-therapeutics-announces-u-s-fda-approval-of-emcitate-tiratricol-for-patients-with-mct8-deficiency-2/ (RareLink™ / PANTHERx® Rare; commercial 8–10 weeks; 1-844-4EGETIS)
• EMA EPAR Emcitate — https://www.ema.europa.eu/en/medicines/human/EPAR/emcitate (Authorised; EC decision 12/02/2025; EMEA/H/C/005220)
• Emcitate EPAR Product Information / SmPC (350 µg dispersible tablets; indication from birth; posology; contraindications; ARs)
• Egetis MFN: Germany launch confirmation (5 May 2025; availability from 1 May 2025)
• Egetis MFN: ReTRIACt topline (14 Nov 2025); EMC Survival abstract notice (21 Aug 2024); prior US expanded access programme update (13 Dec 2023)
• ClinicalTrials.gov NCT02060474, NCT02396459, NCT05579327, NCT05911399 (expanded access status Approved for marketing, verified 2026-10)
• Groeneweg et al., Lancet Diabetes Endocrinol 2019 (Triac Trial I) — DOI 10.1016/S2213-8587(19)30155-X
• van Geest et al., J Clin Endocrinol Metab 2022 (EMC Cohort) — DOI 10.1210/clinem/dgab750
• G-BA Nutzenbewertung Tiratricol / Emcitate procedure 1213 / D-1191; resolution 16 Oct 2025 (hint, non-quantifiable additional benefit)

Authorized is not funded. Not medical advice.

Not medical advice.