Trade Names:Propylthiouracil- Tablets 50 mgPropyl-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.
Long-term therapy of hyperthyroidism; amelioration of hyperthyroidism in preparation for subtotal thyroidectomy or radioactive iodine therapy; when thyroidectomy is contraindicated or not advisable.
Management of alcoholic liver disease.
Hypersensitivity to antithyroid drugs; lactating women.
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.
Give with meals to minimize GI irritation.
Store in tight, light-resistant container at room temperature.
Altered anticoagulant action.Beta blockers
Increased effects of beta blockers.Digitalis glycosides
Increased digitalis levels, resulting in toxicity.Theophylline
Altered theophylline clearance in hyperthyroid or hypothyroid patients.
None well documented.
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.
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.
May cause hypoprothrombinemia and bleeding.
Nausea, vomiting, epigastric distress, headache, fever, arthralgia, pruritus, edema, pancytopenia; most serious effect: agranulocytosis.
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