Propylthiouracil: Difference between revisions

Propylthiouracil
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Revision as of 02:46, 11 December 2024

An antithyroid medication used to treat hyperthyroidism

Propylthiouracil (PTU) is an antithyroid drug used primarily to manage hyperthyroidism, a condition characterized by excessive production of thyroid hormones by the thyroid gland. It is particularly used in cases of Graves' disease, a common cause of hyperthyroidism.

Mechanism of Action

Propylthiouracil works by inhibiting the enzyme thyroid peroxidase, which plays a crucial role in the synthesis of thyroid hormones. This enzyme catalyzes the iodination of tyrosine residues in thyroglobulin and the coupling of iodotyrosines to form triiodothyronine (T3) and thyroxine (T4). By blocking this enzyme, PTU reduces the production of T3 and T4, thereby decreasing the levels of circulating thyroid hormones.

Additionally, propylthiouracil inhibits the peripheral conversion of T4 to the more active T3, further contributing to its antithyroid effects.

Indications

Propylthiouracil is indicated for:

Treatment of hyperthyroidism due to Graves' disease.
Preparation of patients for thyroidectomy or radioactive iodine therapy.
Management of thyroid storm, a life-threatening exacerbation of hyperthyroidism.

Dosage and Administration

The dosage of propylthiouracil varies depending on the severity of the hyperthyroidism and the patient's response to treatment. It is typically administered orally, with doses ranging from 100 mg to 600 mg per day, divided into multiple doses.

Side Effects

Common side effects of propylthiouracil include:

Rash
Nausea
Arthralgia

Serious side effects, though rare, can occur and include:

Agranulocytosis, a potentially life-threatening decrease in white blood cells.
Hepatotoxicity, which can lead to liver failure.

Contraindications

Propylthiouracil is contraindicated in patients with known hypersensitivity to the drug. Caution is advised in patients with pre-existing liver disease.

Pregnancy and Lactation

Propylthiouracil is preferred over methimazole during the first trimester of pregnancy due to the lower risk of teratogenic effects. However, it should be used with caution and under close medical supervision.

Also see

Template:Antithyroid drugs 0

@@ Line 1: / Line 1: @@
-An antithyroid medication.
+{{Short description|An antithyroid medication used to treat hyperthyroidism}}
+{{Drugbox
+| Verifiedfields = changed
+| verifiedrevid = 477002679
+| image = Propylthiouracil.svg
+| width = 200
+| image2 = Propylthiouracil rxn.png
+| width2 = 200
+}}
-{{intro}}
+'''Propylthiouracil''' (PTU) is an [[antithyroid drug]] used primarily to manage [[hyperthyroidism]], a condition characterized by excessive production of [[thyroid hormones]] by the [[thyroid gland]]. It is particularly used in cases of [[Graves' disease]], a common cause of hyperthyroidism.
-Propylthiouracil is an antithyroid medication used in the therapy of hyperthyroidism and Graves disease.
-{{livtox}}
+==Mechanism of Action==
-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.
+Propylthiouracil works by inhibiting the enzyme [[thyroid peroxidase]], which plays a crucial role in the synthesis of thyroid hormones. This enzyme catalyzes the iodination of [[tyrosine]] residues in [[thyroglobulin]] and the coupling of iodotyrosines to form [[triiodothyronine]] (T3) and [[thyroxine]] (T4). By blocking this enzyme, PTU reduces the production of T3 and T4, thereby decreasing the levels of circulating thyroid hormones.
-{{fda}}
-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}}
+[[File:Thyroid hormone synthesis.png|thumb|Diagram of thyroid hormone synthesis, showing the role of thyroid peroxidase.]]
-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.
-{{dose}}
+Additionally, propylthiouracil inhibits the peripheral conversion of T4 to the more active T3, further contributing to its antithyroid effects.
-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.
-{{se}}
+==Indications==
-Common side effects include gastrointestinal upset and rash.  Rare complications of propylthiouracil (<1%) include agranulocytosis, aplastic anemia, nephritis and hepatitis.
+Propylthiouracil is indicated for:
-{{coststubd}}
+* Treatment of hyperthyroidism due to [[Graves' disease]].
+* Preparation of patients for [[thyroidectomy]] or [[radioactive iodine]] therapy.
+* Management of [[thyroid storm]], a life-threatening exacerbation of hyperthyroidism.
+==Dosage and Administration==
+The dosage of propylthiouracil varies depending on the severity of the hyperthyroidism and the patient's response to treatment. It is typically administered orally, with doses ranging from 100 mg to 600 mg per day, divided into multiple doses.
+==Side Effects==
+Common side effects of propylthiouracil include:
+* Rash
+* Nausea
+* Arthralgia
+Serious side effects, though rare, can occur and include:
+* [[Agranulocytosis]], a potentially life-threatening decrease in white blood cells.
+* [[Hepatotoxicity]], which can lead to liver failure.
+==Contraindications==
+Propylthiouracil is contraindicated in patients with known hypersensitivity to the drug. Caution is advised in patients with pre-existing liver disease.
+==Pregnancy and Lactation==
+Propylthiouracil is preferred over [[methimazole]] during the first trimester of pregnancy due to the lower risk of teratogenic effects. However, it should be used with caution and under close medical supervision.
+==Also see==
+* [[Hyperthyroidism]]
+* [[Graves' disease]]
+* [[Thyroid hormone]]
+* [[Methimazole]]
+* [[Thyroidectomy]]
+{{Antithyroid drugs}}
+{{Thyroid diseases}}
+[[Category:Antithyroid drugs]]
+[[Category:Thioamides]]
+[[Category:World Health Organization essential medicines]]