propylthiouracil

What is propylthiouracil, and how does it work (mechanism of action)?

Propylthiouracil (PTU) is an oral medication that is used to manage hyperthyroidism which is due to an overactive thyroid gland. It is an anti-thyroid drug that has a mechanism of action that is similar to methimazole (Tapazole). Graves' disease is the most common cause of hyperthyroidism. It is an autoimmune disease where an individual makes antibodies to thyroid stimulating hormone receptors on cells of the thyroid gland and then trigger overproduction of thyroid hormone by the cells. The two thyroid hormones manufactured by the thyroid gland, thyroxine (T4 ) and triiodothyronine (T3), are formed by combining iodine and a protein called thyroglobulin with the assistance of an enzyme called peroxidase. PTU inhibits iodine and peroxidase from their normal interactions with thyroglobulin to form T4 and T3. This action decreases production of thyroid hormone. PTU also interferes with the conversion of T4 to T3, and, since T3 is more potent than T4, this also reduces the activity of thyroid hormones. The FDA approved PTU in July 1947.

What brand names are available for propylthiouracil?

None available

Is propylthiouracil available as a generic drug?

GENERIC AVAILABLE: Yes

Do I need a prescription for propylthiouracil?

Yes

What are the side effects of propylthiouracil?

The most common side effects are related to the skin, such as:

Other important side effects include:

Less common but serious side effects have occurred with PTU therapy. A decrease of white blood cells in the blood (agranulocytosis) may occur. Symptoms and signs of agranulocytosis include infectious lesions of the throat, the gastrointestinal tract, and skin with an overall feeling of illness and fever.

A decrease in blood platelets (thrombocytopenia) also may occur. Since platelets are important for the clotting of blood, thrombocytopenia may lead to excessive bleeding. Severe liver injury and acute liver failure, in some cases fatal, have been associated with PTU. Some adults and pediatric patients required liver transplantation.

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