Thiamazole |
![]() Last updated: 06/09/2025 |
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(Also known as: methimazole; tapazole; dibazol; methylmercaptoimidazole ) |
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An antithyroid veterinary medication and chemical degradation product of carbimazole | |
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Used for the stabilisation and treatment of hyperthyroidism | |
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Cats |
Approval status |
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Not approved | |
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Not approved |
Chemical structure |
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None | |
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C₄H₆N₂S | |
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CN1C=CNC1=S | |
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No data | |
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PMRYVIKBURPHAH-UHFFFAOYSA-N | |
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InChI=1S/C4H6N2S/c1-6-3-2-5-4(6)7/h2-3H,1H3,(H,5,7) | |
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Yes |
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Common Name | Relationship | Link |
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thiamazole | - | ![]() |
General status |
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Antithyroid drug, Medicinal drug | |
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Human; Animal | |
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Thioamide | |
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Synthetic | |
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Inhibits the addition of iodine to thyroglobulin by the enzyme thyroperoxidase | |
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[Thyroperoxidase, Inhibitor] | |
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60-56-0 | |
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200-482-4 | |
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Systemic hormonal preparations:Thyroid therapy: Sulphur-containing imidazole derivatives | |
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QH03BB02 | |
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No | |
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114.17 | |
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1-methyl-3H-imidazole-2-thione | |
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1-methyl-1,3-dihydroimidazole-2-thione | |
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Beige coloured, odourous powder |
Commercial |
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Current | |||
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1949, developed | |||
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Usually supplied in tablet form for oral administration | |||
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Thiamazole is synthesised through a relatively straightforward chemical process involving the formation of a thiazole ring, which is central to its structure. One efficient method begins with methylimidazole as the starting material, which is reacted with elemental sulphur under heat treatment to induce cyclisation and form the thiazole core. This reaction typically occurs under controlled temperature and solvent conditions to ensure proper ring closure and substitution. After the initial reaction, the crude product is purified through crystallisation or solvent extraction to isolate thiamazole in its active form. | |||
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Published GHG data is not available for most pharmaceuticals. However, according to industry, global averages suggest producing 1 kg of a typical active pharmaceutical ingredient can range from 10 to 100 kg CO₂e for small molecule drugs and potentially up to 1000 kg CO₂e for complex biologicals such as vaccines, depending on the drug type, its formulation, complexity of synthesis, solvent recovery, and energy sources used. |
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2.75 | Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source |
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8000 | E3 E = Manufacturers safety data sheets Ether3 = Unverified data of known source |
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220000 | E3 E = Manufacturers safety data sheets Chloroform3 = Unverified data of known source |
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200000 | E3 E = Manufacturers safety data sheets Methanol3 = Unverified data of known source |
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146 | Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source |
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155 | E3 E = Manufacturers safety data sheets 3 = Unverified data of known source |
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280 | E3 E = Manufacturers safety data sheets 3 = Unverified data of known source |
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47 | E3 E = Manufacturers safety data sheets 3 = Unverified data of known source |
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5.01 X 10-01 | Calculated | - | |||||||
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-0.3 | E3 E = Manufacturers safety data sheets 3 = Unverified data of known source |
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1.36 | Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source |
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Degradation |
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As this parameter is not normally measured directly, a surrogate measure is used: ‘Photochemical oxidative DT₅₀’. Where data is available, this can be found in the Fate Indices section below. | ||||||||||
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Fate indices |
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Known soil and groundwater metabolites |
None
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glucuronide | - | Animals (Urine) | - |
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Terrestrial ecotoxicology |
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> 2250 | E3 E = Manufacturers safety data sheets Rat3 = Unverified data of known source |
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Aquatic ecotoxicology |
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General |
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High (class III) | - | - | ||||||||
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> 2250 | E3 E = Manufacturers safety data sheets Rat3 = Unverified data of known source |
Low | ||||||||
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Subcutaneous LD₅₀ = 1050 mg kg⁻¹ | V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) Rat3 = Unverified data of known source |
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Intraperitoneal LD₅₀ = 500 mg kg⁻¹ | V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) Mouse3 = Unverified data of known source |
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Some metabolism, parent and metabolites excreted in urine and faeces | V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source |
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Health issues |
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May cause joint and muscle pain, drowsiness or dizziness Possible blood, liver, endocrine and thyroid toxicant |
Handling issues |
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Slightly flammable Emits toxic fumes of nitroxides and sulfoxides in a fire Risk of dust explosion |
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Health: H302, H317, H319, H361 | |||
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Not listed (Not listed) | |||
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thiamazole | ||
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thiamazol | ||
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tiamazol | ||
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Record last updated: | 06/09/2025 |
Contact: | aeru@herts.ac.uk |
Please cite as: | Lewis, K.A., Tzilivakis, J., Warner, D. and Green, A. (2016) An international database for pesticide risk assessments and management. Human and Ecological Risk Assessment: An International Journal, 22(4), 1050-1064. DOI: 10.1080/10807039.2015.1133242 |