Methimazole is a thionamide antithyroid agent that inhibits the synthesis of thyroid hormones.[A184559,A184733,A184694] It was first introduced as an antithyroid agent in 1949[A184502] and is now commonly used in the management of hyperthyroidism, particularly in those for whom more aggressive options such as surgery or radioactive iodine therapy are inappropriate.[L8336,L8339] On a weight basis, methimazole is 10 times more potent than the other major antithyroid thionamide used in North America, [propylthiouracil],[L8339] and is the active metabolite of the pro-drug [carbimazole], which is an antithyroid medication used in the United Kingdom and parts of the former British Commonwealth.[A184733] Traditionally, methimazole has been preferentially used over propylthiouracil due to the risk of fulminant hepatotoxicity carried by the latter,[A184757] with propylthiouracil being preferred in pregnancy due to a perceived lower risk of teratogenic effects. Despite documented teratogenic effects in its published labels,[L8336,L8339] the true teratogenicity of methimazole appears to be unclear[A184643,A184757,A184763] and its place in therapy may change in the future.
Synonyms
Thiamazole
1-Methylimidazole-2(3H)-thione
Tiamazol
Methimazole
Thiamazolum
Thiamazol
Brand Names
Methimazole Tablets USP
PHL-methimazole
Mar-methimazole
PMS-methimazole
Tapazole
Methimazole
Dom-methimazole
Apo-methimazole
Jamp Methimazole
Indication
In the United States, methimazole is indicated for the treatment of hyperthyroidism in patients with Graves' disease or toxic multinodular goiter for whom thyroidectomy or radioactive iodine therapy are not appropriate treatment options. Methimazole is also indicated for the amelioration of hyperthyroid symptoms in preparation for thyroidectomy or radioactive iodine therapy.[L8336] In Canada, methimazole carries the above indications and is also indicated for the medical treatment of hyperthyroidism regardless of other available treatment options.[L8339]
Drug Info/Drug Targets: DrugBank 3.0: a comprehensive resource for 'omics' research on drugs. Knox C, Law V, Jewison
T, Liu P, Ly S, Frolkis A, Pon A, Banco K, Mak C, Neveu V, Djoumbou Y, Eisner R, Guo AC, Wishart DS.
Nucleic Acids Res. 2011 Jan; 39 (Database issue):D1035-41. | PMID:21059682
