thiouracil

Thiouracil is a **small molecule** belonging to the class of **antithyroid agents**, specifically **thiourea derivatives**. It acts as a classic inhibitor of thyroid function and was historically used to treat hyperthyroidism prior to the adoption of related drugs such as propylthiouracil and methimazole. Thiouracil’s mechanism involves inhibition of the enzyme **thyroid peroxidase**, thereby blocking the organification of iodine and coupling of iodotyrosines, which are essential steps in the synthesis of thyroid hormones thyroxine (T4) and triiodothyronine (T3). By reducing thyroid hormone synthesis, thiouracil decreases metabolic activity in hyperthyroid states. Use of thiouracil in clinical practice has been largely discontinued due to its relatively low potency and higher risk of side effects compared to newer antithyroid agents.

Other names

2-thiouracil2-thioxopyrimidin-4(3H)-one