Propylthiouracil—Antithyroid Drugs

RX for hypothyroidism. In USA, 7.5% of pregnant women plus an additional 500,000 people per y develop hyperthyroidism.

Rx for goiter associated with hyperthyroidism; second drug to methimazole due to greater side effects with PTU except in pregnancy (methimazole has greater side effects on fetus during pregnancy).

Definitive Rx for control of hyperthyroidism in anticipation of spontaneous remission.

Rx for hyperthyroidism in conjunction with ¹³¹ I or ¹²⁵ I to hasten recovery while awaiting effects of radiation therapy.

Secondary Rx for hyperthyroidism to control disorder in preparation for surgery.

Side effects of drug: Hypothyroidism; liver failure, especially in pts with liver transplants; be careful in pregnancy.

Agranulocytosis (less than 0.5% of treated pts develop this side effect) and liver problems

Antithyroid drug: Absorbed within 20–30 min; effect begins to decrease in 2–3 h (half-life of methimazole estimated to be 6–13 h).

Drug and metabolites cleared by renal excretion.

Antithyroid drugs cross placenta, can be found in breast milk.