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Drugs reference index «Propylthiouracil»


Pronunciation: (pro-puhl-thigh-oh-YOU-rah-sill)Class: Antithyroid agent

Trade Names:Propylthiouracil- Tablets 50 mg

Propyl-Thyracil (Canada)


Inhibits synthesis of thyroid hormones.



Readily absorbed from the GI tract. Bioavailability is 80% to 95%. T max is 1.99 h; C max is 7.12 mcg/mL.


Protein binding is 75% to 80%, primarily to albumin. Vd is approximately 0.4 L/kg.


Actively concentrated by the thyroid. Metabolized rapidly in the liver; undergoes glucuronidation.


Urine (35%); less than 1% as unchanged. T ½ is 1 to 2 h. Total body clearance is approximately 7 L/h.


Approximately 17 wk to normalize serum T 3 and T 4 concentrations.

Indications and Usage

Long-term therapy of hyperthyroidism; amelioration of hyperthyroidism in preparation for subtotal thyroidectomy or radioactive iodine therapy; when thyroidectomy is contraindicated or not advisable.

Unlabeled Uses

Management of alcoholic liver disease.


Hypersensitivity to antithyroid drugs; lactating women.

Dosage and Administration


PO The initial dose is 300 mg/day in 3 equal doses every 8 h. In patients with severe hyperthyroidism or very large goiters, initial dose is usually 400 mg/day, occasionally up to 600 to 900 mg/day. The maintenance dose is 100 to 150 mg/day in divided doses every 8 h.

Children older than 10 yr of age

PO The initial dose is 150 to 300 mg/day in divided doses every 8 h. The maintenance dose is determined by response.

Children 6 to 10 yr of age

PO The initial dose is 50 to 150 mg/day in divided doses every 8 h.

Alternate Dosing for Children

PO The initial dose is 5 to 7 mg/kg/day in divided doses every 8 h. The maintenance dose is 1/ 3 to 2/ 3 initial dose, beginning when patient is euthyroid.

General Advice

Give with meals to minimize GI irritation.


Store in tight, light-resistant container at room temperature.

Drug Interactions


Altered anticoagulant action.

Beta blockers

Increased effects of beta blockers.

Digitalis glycosides

Increased digitalis levels, resulting in toxicity.


Altered theophylline clearance in hyperthyroid or hypothyroid patients.

Laboratory Test Interactions

None well documented.

Adverse Reactions


Paresthesias; neuritis; headache; vertigo; drowsiness; neuropathies; CNS stimulation; depression.


Rash; urticaria; pruritus; erythema nodosum; skin pigmentation; exfoliative dermatitis; lupus-like syndrome (splenomegaly, hepatitis, periarteritis; hypoprothrombinemia; bleeding).


Loss of taste; sialadenopathy.


Nausea; vomiting; epigastric distress.




Jaundice; hepatitis.


Inhibition of myelopoiesis (eg, agranulocytosis, leukopenia, granulocytopenia, thrombocytopenia); aplastic anemia; hypoprothrombinemia; periarteritis.


Abnormal hair loss; arthralgia; myalgia; edema; lymphadenopathy; drug fever; interstitial pneumonitis; insulin autoimmune syndrome (hypoglycemia).



Category D .


Avoid breast-feeding. However, if antithyroid drug is essential, propylthiouracil is preferred antithyroid agent while breast-feeding.


Hepatotoxicity has occurred in children. Discontinue drug immediately if signs and symptoms of hepatic function impairment develop.


Potentially most serious adverse reaction. Discontinue drug if agranulocytosis, aplastic anemia, hepatitis, fever, or exfoliative dermatitis occur.

Hemorrhagic effects

May cause hypoprothrombinemia and bleeding.



Nausea, vomiting, epigastric distress, headache, fever, arthralgia, pruritus, edema, pancytopenia; most serious effect: agranulocytosis.

Patient Information

  • Instruct patient to take resting pulse daily and encourage patient to keep recorded chart.
  • Advise patient to monitor weight at least 2 to 3 times/wk or per health care provider instruction, obtaining weight at same time, using same scale. Encourage patient to keep recorded chart.
  • Emphasize importance of following dietary restrictions regarding shellfish, iodized salt, and other foods high in iodine.
  • Explain that desired response may take several months if the thyroid is greatly enlarged.
  • Advise patient to carry medical identification (eg, card, bracelet) at all times describing medications.
  • Instruct patient to notify dentist or health care provider of drug regimen before surgical or dental procedures.
  • Emphasize importance of follow-up visits to monitor effectiveness of drug therapy.
  • Caution patient not to stop taking medication abruptly to avoid thyroid crisis.
  • Instruct patient to report the following symptoms to health care provider: Sore throat, fever, rash, mouth sores; cold intolerance, mental depression; tachycardia, irritability; persistent nausea, steatorrhea or vomiting, drowsiness, yellowing of skin or whites of eyes; unusual bleeding or bruising.
  • Advise patient that drug may cause drowsiness and to use caution while driving or performing other activities requiring mental alertness.

Copyright © 2009 Wolters Kluwer Health.

  • Propylthiouracil MedFacts Consumer Leaflet (Wolters Kluwer)
  • Propylthiouracil Prescribing Information (FDA)
  • propylthiouracil Advanced Consumer (Micromedex) - Includes Dosage Information
  • propylthiouracil Concise Consumer Information (Cerner Multum)

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