Thiamazole Chemical formula
Synonyms: Mercazolylum; Methimazole; Methylmercaptoimidazole; Metimazol; Thiamazol; Thiamazolum; Tiamatsoli; Tiamazol; Tiamazolas. 1-Methylimidazole-2-thiol.
Cyrillic synonym: Тиамазол.

💊 Chemical information

Chemical formula: C4H6N2S = 114.2.
CAS — 60-56-0.
ATC — H03BB02.
ATC Vet — QH03BB02.


In Chin., Eur., Jpn, and US.

Ph. Eur. 6.2

(Thiamazole). A white or pale brown, crystalline powder. Freely soluble in water and in dichloromethane; freely soluble or soluble in alcohol.

USP 31

(Methimazole). A white to pale buff crystalline powder having a faint characteristic odour. Soluble 1 in 5 of water, 1 in 5 of alcohol, 1 in 4.5 of chloroform, and 1 in 125 of ether. Its solutions are practically neutral to litmus. Protect from light.

💊 Adverse Effects and Precautions

As for Carbimazole.

Breast feeding.

The use of thiamazole during breast feeding is discussed under Carbimazole.

💊 Pharmacokinetics

The pharmacokinetics of thiamazole can be considered with those of carbimazole since the latter is rapidly and completely metabolised to thiamazole in the body.

💊 Uses and Administration

Thiamazole is a thiourea antithyroid drug that acts by blocking the production of thyroid hormones. It is used in the management of hyperthyroidism, including the treatment of Graves’ disease, the preparation of hyperthyroid patients for thyroidectomy, use as an adjunct to radio-iodine therapy, and the treatment of thyroid storm. Thiamazole is given orally usually in an initial dosage of 15 to 60 mg daily. It is usually given in three divided doses but a single daily dose is also possible. Improvement is usually seen in 1 to 3 weeks and control of symptoms in 1 to 2 months. When the patient is euthyroid the dose is gradually reduced to a maintenance dose, usually 5 to 15 mg daily. Alternatively, the dose may be continued at the initial level with supplemental levothyroxine as a blocking-replacement regimen. Either form of maintenance treatment is usually continued for 1 to 2 years. The initial dose for children is 400 micrograms/kg daily in 3 divided doses; for maintenance this dose may be halved. Thiamazole doses of 80 to 240 mg daily, usually in 3 or 4 divided doses, have been given intravenously in the management of thyroid storm.

💊 Preparations

USP 31: Methimazole Tablets.

Proprietary Preparations

Arg.: Danantizol; Austria: Favistan†; Belg.: Strumazol; Braz.: Ta p a z o l ; Canad.: Ta p a z o l e ; Chile: Thyrozol; Tirozol 5/10†; Cz.: Favistan†; Thyrozol; Denm.: Thycapzol; Ger.: Favistan; Thyrozol; Gr.: Unimazole; Hung.: Metothyrin; Indon.: Thyrozol; Israel: Mercaptizol; Ital.: Ta p a z o l e ; Mex.: Ta pazol; Tizorol; Neth.: Strumazol; Philipp.: Strumazol; Tapazole; Pol.: Metizol; Thyrozol; Port.: Metibasol; Rus.: Mercazolil (Мерказолил); Thyrozol (Тирозол); Singapore: Thyrozol; Spain: Tirodril; Swed.: Thacapzol; Switz.: Tapazole†; Thai.: Tapazole; Timazol; Turk.: Thyromazol; USA: Northyx; Tapazole; Venez.: Ta p a z o l . Multi-ingredient: Ital.: Bromazolo.
Published October 31, 2018.