Methylthiouracil

Methylthiouracil is an organosulfur compound that is used antithyroid preparation. It is a thioamide, closely related to propylthiouracil. Methylthiouracil is not used clinically in the United States, it has a similar mechanism of action and side effect to that of propylthiouricil. The drug acts to decrease the formation of stored thyroid hormone, as thyroglobulin in the thyroid gland. The clinical effects of the drug to treat the hyperthyroid state can have a lag period of up to two weeks, depending on the stores of thyroglobulin and other factors.

Methylthiouracil

Clinical data
AHFS/Drugs.com	International Drug Names
ATC code	H03BA01 (WHO)
Identifiers
IUPAC name 6-methyl-2-thioxo-2,3-dihydropyrimidin-4(1H)-one
CAS Number	56-04-2
PubChem CID	667493
ChemSpider	580871
UNII	QW24888U5F
KEGG	C19265 Y
ChEMBL	ChEMBL1330588
CompTox Dashboard (EPA)	DTXSID2020890
ECHA InfoCard	100.000.230
Chemical and physical data
Formula	C5H6N2OS
Molar mass	142.18 g·mol−1
3D model (JSmol)	Interactive image
SMILES CC1=CC(=O)NC(=S)N1
InChI InChI=1S/C5H6N2OS/c1-3-2-4(8)7-5(9)6-3/h2H,1H3,(H2,6,7,8,9) Key:HWGBHCRJGXAGEU-UHFFFAOYSA-N
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Synthesis

Methylthiouracil synthesis:^[1]

Methylthiouracil is prepared quite simply by condensation of ethyl acetoacetate with thiourea.^[2]

Further work in this series shows that better activity was obtained by incorporation of a lipophilic side chain.