NCIt definition : A thiourea derivative with antithyroid property. Propylthiouracil (PTU) interferes
with the oxidation of iodine possibly by interaction with peroxidase or a peroxidase-mediated
complex reaction, thereby inhibiting synthesis of thyroid hormones tri-iodothyronine
(T3) and thyroxine (T4). In addition, this agent inhibits the Type I 5'-deiodinase
(D1), an enzyme involved in the peripheral conversion of thyroxine to tri-iodothyronine.
This results in decreased plasma triodothyronine concentrations and decreased entrance
of thyroxine into cells thereby reducing thyroid hormone activity.;