Propylthiouracil

An antithyroid medication.

Information about Propylthiouracil

Propylthiouracil is an antithyroid medication used in the therapy of hyperthyroidism and Graves disease.

Liver safety of Propylthiouracil

Propylthiouracil has been linked to serum aminotransferase elevations during therapy as well as to a clinically apparent, idiosyncratic liver injury that can be severe and even fatal.

FDA approval information for Propylthiouracil

Propylthiouracil (proe" pil thye" oh ure' a sil) is a thioamide and a thyroid hormone antagonist which acts by inhibiting the incorporation of iodine into tyrosyl residues of thyroglobulin and thus lowering thyroid hormone levels. Propylthiouracil may also partially inhibit the peripheral deiodination of thyroxine [T4] to the active form [T3] and, in addition, may have immunosuppressive activities.

FDA approval information for Propylthiouracil

Propylthiouracil was introduced into use in the 1940s and is still used for the temporary amelioration of hyperthyroidism in Graves disease in patients with mild or self-limited hyperthyroidism. However, because of the problems with hepatotoxicity including fatal cases of hepatitis, propylthiouracil is now considered a second line drug for hyperthyroidism, methimazole being preferred. Thus, propylthiouracil is currently used largely in patients who are intolerant to methimazole in preparation of definitive therapy or who wish to avoid thyroidectomy or radioactive iodine therapy.

Dosage and administration for Propylthiouracil

Generic forms of propylthiouracil are available in 50 mg tablets. The usual dose in adults is 300 to 450 mg daily in divided doses until the patient is euthyroid, followed by a maintenance dose of 100 to 150 mg daily.

Side effects of Propylthiouracil

Common side effects include gastrointestinal upset and rash. Rare complications of propylthiouracil (<1%) include agranulocytosis, aplastic anemia, nephritis and hepatitis.

• Dailymed label info on Propylthiouracil
• FDA Propylthiouracil