Tiratricol
CAS 51-24-1, 1477-04-9 (hydrochloride salt)
MFC14H9I3O4 MW621.93 g/mol
9/28/2026, Emcitate, FDA 2026, APPROVALS 2026, Triac
2-[4-(4-hydroxy-3-iodophenoxy)-3,5-diiodophenyl]acetic acid
- 3,3',5-TRIIODOTHYROACETIC ACID
- Triiodothyroacetic acid
To treat peripheral thyrotoxicosis in patients with MCT8 deficiency
Tiratricol is a monocarboxylic acid that is (4-hydroxy-3,5-diiodophenyl)acetic acid in which the phenolic hydroxy group has been replaced by a 4-hydroxy-3-iodophenoxy group. It is a thyroid hormone analogue that has been used in the treatment of thyroid hormone resistance syndrome. It has a role as an antiviral agent, a nutraceutical, a thyroid hormone, an anti-obesity agent, an EC 1.3.5.2 [dihydroorotate dehydrogenase (quinone)] inhibitor and a human metabolite. It is a monocarboxylic acid, a member of phenols, an aromatic ether and an organoiodine compound
Tiratricol (also known as TRIAC or triiodothyroacetic acid), sold under the brand name Emcitate, is a thyroid hormone analogue. Triiodothyroacetic acid is also a physiologic thyroid hormone that is present in the normal organism in low concentrations. Tiratricol is an analogue of a naturally circulating metabolite of the active thyroid hormone T3.[1] MCT8 is a specific thyroid hormone transporter.[1] While T3 and T4 thyroid hormones rely on MCT8 to enter several tissues such as the brain, tiratricol can enter cells independently of MCT8.[1] Once inside cells, tiratricol activates the thyroid hormone receptor in a similar way to endogenous T3.[1]
The most common side effects are excessive sweating, irritability, anxiety and nightmares.[1]
Medical uses
Tiratricol is indicated in the management of thyroid hormone resistance syndrome.[3]
In the United States, Tiratricol is indicated for the treatment of peripheral thyrotoxicosis in adults and pediatric patients with MCT8 deficiency (Allan–Herndon–Dudley syndrome).[4][5]
Society and culture
Legal status
Tiratricol is not approved for sale in Canada. It was once an approved medication in Brazil, but its marketing authorization was suspended in 2003, effectively prohibiting its sale.[6] Tiratricol is available in France for therapy of thyroid hormone resistance and adjuvant therapy of thyroid cancer.[7]
In December 2024, the Committee for Medicinal Products for Human Use of the European Medicines Agency adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Emcitate, intended for the treatment of MCT8 deficiency (Allan-Herndon-Dudley syndrome).[1][8] The applicant for this medicinal product is Rare Thyroid Therapeutics International AB.[1] Emcitate is a hybrid medicine of Téatrois, which has been authorized in France.[1] Emcitate contains the same active substance as Téatrois but has a different indication.[1] Tiratricol was authorized for medical use in the European Union in February 2025.[1][2] Tiratricol was approved for medical use in the United States kn September 2026.[5]
Research
Tiratricol has been investigated for use in reducing goiter.[9]
It has also shown some effectiveness in reducing the atrophy caused when using corticosteroids.[10]
Tiratricol has also been widely marketed, under various trade names, as a weight loss aid. In 1999 and 2000, the United States Food and Drug Administration and Health Canada both issued warnings to the public regarding the use of dietary supplements containing tiratricol.[11][12]
LIT
C. E. Wilkinson (Biochem. J. 63, 601, 1956): The primary landmark study describing the controlled iodination approach to yield triiodothyroacetic acid.
Meltzer et al. (J. Org. Chem. 26, 1418, 1961): Advanced methods for the synthesis and purification of thyroacetic acid derivatives.
PAT
British Patent GB 803149 (1958)
https://patentscope.wipo.int/search/en/detail.jsf?docId=GB134699786&_cid=P10-MUQCJP-66503-1
EXAMPLE 1 3:5:31 - triiodo - 4 - (41 - hydroxyphenoxy)
phenyl acetic acid (Triac)
An aqueous solution of iodine (N: 40 mls.) was added dropwise with stirring during hour to a solution of 3:5-diiodo-4-(41hydroxyphenoxy)phenyl acetic acid (Diac) (9.92 g.; 0.02 mol.) in aqueous ethylamine (33%: 120 mls.). After a further hour the solution was acidified with hydrochloric acid (5N) at 10-15 (ice-bath cooling). The precipitate, which became gummy on filtration, was triturated with water containing a few drops of hydrochloric acid and again filtered.
The solid was then ground with water containing a little hydrochloric acid, filtered, washed with water and dried over phosphorus pentoxide (12.10 g.; m.p. 161-72 ). The crude product was dissolved in methanol (240 mls.) and stirred during the dropwise addition of water (180 mls.). After standing overnight, the mixture was decanted from the tarry material which had separated. Water (60 mls.) was added in one portion, and the milky solution allowed to stand several hours until crystallisation was complete. The product was collected and dried over phosphorus pentoxide, 7.1 g. (63%) m.p. 181-3 (after sinteringg at about 60 , effervescing at 100 and resolidifying at about 115 ). A sample from a previous experiment was dried by heating slowly to 100 in high vacuum over phosphorus pentoxide. Found: C, 27.3; H, 1.5; I, 61.2, C14H9O4I3 requires C, 27.0; H, 1.5; I, 61.2%.
To prepare the sodium salt of Triac 42.8 g. of Triac was dissolved in a hot solution of sodium carbonate (7.3 g.) in water (420 mis.) and filtered. A solution of salt (35%; 42 mis.) was added and the mixture cooled, finally in the refrigerator. The product was collected and dried to constant weight over phosphorus pentoxide (34.1 g.).
PAT
British Patent GB 805761 (1958)
PAT
US Patent US8071134B2
https://patentscope.wipo.int/search/en/detail.jsf?docId=US42563548&_cid=P10-MUQCHB-64862-1
PAT
Chinese Patent CN113181152B
https://patentscope.wipo.int/search/en/detail.jsf?docId=CN333439736&_cid=P10-MUQCEZ-62879-1
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References
- "Emcitate EPAR". European Medicines Agency (EMA). 12 December 2024. Retrieved 16 December 2024. Text was copied from this source which is copyright European Medicines Agency. Reproduction is authorized provided the source is acknowledged.
- "Emcitate PI". Union Register of medicinal products. 17 February 2025. Retrieved 27 February 2025.
- Carvalho GA, Ramos HE (2004). "[Thyroid hormone resistance syndrome]" (PDF). Arq Bras Endocrinol Metabol (in Portuguese). 48 (1): 83–92. doi:10.1590/S0004-27302004000100010. PMID 15611821.
- "EMCITATE — Now Approved". EMCITATE® — Now Approved. Retrieved 29 September 2026.
- "Egetis Therapeutics Announces U.S. FDA Approval of EMCITATE® (tiratricol) for Patients with MCT8 Deficiency". Egetis Therapeutics. Retrieved 29 September 2026.
- "Anvisa suspende Tiratricol" (in Portuguese). Brazilian Society of Endocrinology and Metabolism. Archived from the original on 9 October 2007. Retrieved 8 August 2007.
- Laboratoires DB PHARMA: Teatrois Deprecated link archived 2015-01-19 at archive.today information
- "First treatment for peripheral thyrotoxicosis in patients with Allan-Herndon-Dudley syndrome". European Medicines Agency (EMA) (Press release). 13 December 2024. Retrieved 16 December 2024.
- Brenta G, Schnitman M, Fretes O, et al. (November 2003). "Comparative efficacy and side effects of the treatment of euthyroid goiter with levo-thyroxine or triiodothyroacetic acid". J. Clin. Endocrinol. Metab. 88 (11): 5287–92. doi:10.1210/jc.2003-030095. PMID 14602763.
- Yazdanparast P, Carlsson B, Oikarinen A, Risteli J, Lavin T, Faergemann J (November 2006). "Action of topical thyroid hormone analogue, triiodothyroacetic acid in reversing glucocorticoid-induced skin atrophy in humans". Thyroid. 16 (11): 1157–62. doi:10.1089/thy.2006.16.1157. PMID 17123343.
- "FDA Warns Against Consuming Dietary Supplements Containing Tiratricol" (Press release). U.S. Food and Drug Administration. 21 November 2000. Archived from the original on 22 January 2001. Retrieved 8 August 2007.
- "Health Canada issues warning on products containing Tiratricol (TRIAC)" (Press release). Health Canada. 2 December 1999. Retrieved 8 August 2007.
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 | |
| Clinical data | |
|---|---|
| Trade names | Emcitate |
| Other names | 3,3',5-triiodothyroacetic acid TRIAC |
| AHFS/Drugs.com | International Drug Names |
| Drug class | Thyroid hormone |
| ATC code | H03AA04 (WHO) D11AX08 (WHO) |
| Legal status | |
| Legal status | EU: Rx-only[1][2] |
| Pharmacokinetic data | |
| Metabolism | Liver glucuronidation |
| Excretion | Bile duct |
| Identifiers | |
| IUPAC name | |
| CAS Number | 51-24-1  |
| PubChem CID | 5803 |
| IUPHAR/BPS | 2637 |
| DrugBank | DB03604  |
| ChemSpider | 5598 |
| UNII | 29OQ9EU4R1 |
| KEGG | D07214 |
| ChEBI | CHEBI:40021 |
| ChEMBL | ChEMBL41632 |
| CompTox Dashboard (EPA) | DTXSID2045232  |
| ECHA InfoCard | 100.000.079 |
| Chemical and physical data | |
| Formula | C14H9I3O4 |
| Molar mass | 621.935 g·mol−1 |
| 3D model (JSmol) | Interactive image |
| SMILES | |
| InChI | |
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