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a thyroid inhibitor used to treat hyperthyroidism; administered orally.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

propylthiouracil (PTU)

Propyl-Thyracil (CA)

Pharmacologic class: Thioamide derivative

Therapeutic class: Antithyroid agent

Pregnancy risk category D

FDA Box Warning

• Drug has caused severe liver injury and acute liver failure, in some cases fatal. These reports of hepatic reactions include cases requiring liver transplant.

• Reserve drug for patients intolerant of methimazole and in whom radioactive iodine therapy or surgery isn't appropriate for management of hyper-thyroidism.

• Because of risk of fetal abnormalities associated with methimazole, propylthiouracil may be treatment of choice when an antithyroid drug is indicated during or just before first trimester.


Directly interferes with thyroid synthesis by preventing iodine from combining with thyroglobulin, leading to decreased thyroid hormone levels


Tablets: 50 mg

Indications and dosages


Adults: Initially, 300 to 450 mg P.O. daily in equally divided doses q 8 hours; for maintenance, 100 to 150 mg P.O. daily.

Thyrotoxic crisis

Adults: 200 mg P.O. q 4 to 6 hours during first 24 hours, then a maintenance dosage of 100 to 150 mg P.O. daily


• Hypersensitivity to drug


Use cautiously in:

• decreased bone marrow reserve

• pregnancy and breastfeeding patients

• children.


• Give with meals to reduce GI upset.

• Be aware that drug shouldn't be used in children unless patient is allergic to or intolerant of methimazole, and there are no other treatment options available.

Adverse reactions

CNS: drowsiness, headache, vertigo, neuritis, paresthesia

GI: nausea, vomiting, diarrhea, epigastric distress

Hematologic: agranulocytosis, leukopenia, thrombocytopenia

Hepatic: jaundice, hepatic necrosis, liver failure

Metabolic: hypothyroidism

Musculoskeletal: joint pain, myalgia

Skin: rash, urticaria, pruritus, skin discoloration, alopecia, cutaneous vasculitis

Other: taste loss, fever, lymphadenopathy, parotitis, edema


Drug-drug. Anticoagulants: potentiation of anticoagulant effect

Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, bilirubin, lactate dehydrogenase: increased levels

Granulocytes, platelets: decreased levels Prothrombin time: prolonged

Patient monitoring

• Monitor CBC and liver and thyroid function tests.

• Assess for signs and symptoms of hypothyroidism (cold intolerance, nonpitting edema, fatigue, weight gain, and depression).

Monitor for severe rash, fever, jaundice, or enlarged cervical lymph nodes. If present, stop therapy and notify prescriber.

Patient teaching

• Instruct patient to take with meals to reduce GI upset.

• Teach patient to recognize and report signs and symptoms of hypothyroidism and jaundice.

• Advise patient to discuss iodine intake (as in iodized salt and shellfish) with prescriber.

• Tell patient to avoid over-the-counter cold remedies that contain iodine.

• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.

• Advise female patient of childbearing age to discuss pregnancy or breastfeeding with prescriber before taking.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.

McGraw-Hill Nurse's Drug Handbook, 7th Ed. Copyright © 2013 by The McGraw-Hill Companies, Inc. All rights reserved

pro·pyl·thi·o·u·ra·cil (PTU),

An antithyroid agent that inhibits the synthesis of thyroid hormones; used in the treatment of hyperthyroidism; a goitrogen.
Farlex Partner Medical Dictionary © Farlex 2012


Abbr. PTU A drug, C7H10N2OS, that inhibits the synthesis of thyroid hormones and is used to treat hyperthyroidism.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


(PT) (prō'pil-thī'ō-yūr'ă-sil)
An antithyroid agent that inhibits synthesis of thyroid hormones; used to treat hyperthyroidism.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


A drug used to treat overactivity of the thyroid gland (hyperthyroidism). The drug is on the WHO official list.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


An agent used to treat hyperthyroidism; a goitrogen.
Medical Dictionary for the Dental Professions © Farlex 2012
References in periodicals archive ?
Hershman, "Propylthiouracil blocks extrathyroidal conversion of thyroxine to triiodothyronine and augments thyrotropin secretion in man," Journal of Clinical Investigation, vol.
Effects of propylthiouracil and methimazole on fetal thyroid status in mothers with Graves' hyperthyroidism.
(9.) Lee H, Hirouchi M, Hosokawa M, Sayo H, Kohno M & Kariya K.Inactivation of peroxidase of rate bone marrow by repeated administration of propylthiouracil is accompanied by a change in the heme structure.
Both Carbimazole and Propylthiouracil differ in their mechanisms of causation of liver damage.
Propylthiouracil tablet Labeled claim (mg) 50.0 Amount found (mg) (a) 49.0 RSD (%) 0.65 Bias (%) -2.0 Added (mg) 5.00 Found (mg) (a) 4.92 Recovered (%) 98.4 RSD (%) 0.38 Calculated F 1.24 Calculated t 2.16 Bias (%) -1.6 (a) Mean average of five determinations.
Itoh et al., "Comparison of methimazole and propylthiouracil in patients with hyperthyroidism caused by Graves' disease," Journal of Clinical Endocrinology and Metabolism, vol.
Barr, "Low-dose oral propylthiouracil in the treatment of plaque psoriasis," International Journal of Dermatology, vol.
When treating women with thyroid dysfunction during and after pregnancy, clinicians should use caution interpreting serum-free thyroxine levels, use propylthiouracil as the first-line drug during for hyperthyroidism in the first trimester, and advise breastfeeding women to maintain a daily intake of 250 mcg of iodine to ensure breast milk provides 100 mcg of iodine/day to the infant.
Neonatal hypothyroidism causes delayed Sertoli cell maturation in rats treated with propylthiouracil: evidence that the Sertoli cell controls testis growth.
For these analyses, we excluded subjects who were receiving concurrent treatment with drugs that could contribute to hypothyroidism (lithium, amiodarone, or iodine), those receiving antithyroid medication (methimazole or propylthiouracil) for hyperthyroidism and treatment with lipid lowering drugs for dyslipidemia.
The underlying cause must be addressed with antithyroid medications (such as propylthiouracil or methimazole) or ablation of the thyroid.