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Propylthiouracil
Propylthiouracil (Propyl-Thyracil)
Propylthiouracil
(proh-pill-thigh-oh-YOUR-ah-sill)
Pregnancy Category: D
Propyl-Thyracil
(Rx)
Classification:
Antithyroid preparation
Action/Kinetics:
Inhibits (partially or completely) the production of thyroid hormones by the thyroid gland by preventing the incorporation of iodide into tyrosine and coupling of iodotyrosines. Does not affect release or activity of preformed hormone; thus, it may take several weeks for the therapeutic effect to become established.
May be preferred for treatment of thyroid storm, as it inhibits peripheral conversion of thyroxine to triiodothyronine. Rapidly absorbed from the GI tract. Duration: 2-3 hr. t1/2: 1-2 hr. Onset: 10-20 days. Time to peak effect: 2-10 weeks. Eighty percent is protein bound. Metabolized by the liver and excreted through the kidneys.
Uses:
Hyperthyroidism; prior to surgery or radiotherapy. Adjunct in treatment of thyrotoxicosis or thyroid storm. To reduce mortality due to alcoholic liver disease.
Contraindications:
Lactation--may cause hypothyroidism in infant.
Special Concerns:
Incidence of vasculitis is increased. Use with caution in the presence of CV disease. Monitor PT due to possible hypoprothrombinemia and bleeding.
Side Effects:
Hematologic: Agranulocytosis thrombocytopenia, granulocytopenia, hypoprothrombinemia, aplastic anemia leukopenia. GI: N&V;, taste loss, epigastric pain, sialadenopathy. CNS: Headache, paresthesia, drowsiness, vertigo, depression, CNS stimulation. Dermatologic: Skin rash, urticaria, alopecia, skin pigmentation, pruritus, exfoliative dermatitis, erythema nodosum. Miscellaneous: Jaundice, arthralgia, myalgia, neuritis, edema, lymphadenopathy, vasculitis, lupus-like syndrome, drug fever, periarteritis, hepatitis, nephritis, interstitial pneumonitis, insulin autoimmune syndrome resulting in hypoglycemic coma.
Overdose Management:
Symptoms: N&V;, headache, fever, pruritus, epigastric distress, arthralgia, pancytopenia, agranulocytosis (most serious). Rarely, exfoliative dermatitis, hepatitis, neuropathies, CNS stimulation or depression. Treatment: Maintain a patent airway and support ventilation and perfusion. Very carefully monitor and maintain VS, blood gases, and serum electrolytes. Monitor bone marrow function.
Drug Interactions:
Propylthiouracil may produce hypoprothrombinemia, adding to the effect of anticoagulants.
How Supplied:
Tablet: 50 mg
Dosage
•Tablets
Hyperthyroidism.
Adults, initial: 300 mg/day (up to 900 mg/day may be required in some clients with severe hyperthyroidism) given as one to four divided doses; maintenance, usual: 100-150 mg/day. Pediatric, 6-10 years, initial: 50-150 mg/day in one to four divided doses; over 10 years, initial: 150-300 mg/day in one to four divided doses. Maintenance for all pediatric use is based on response. Alternative dose for children, initial: 5-7 mg/kg/day (150-200 mg/m2/day) in divided doses q 8 hr; maintenance: 1/3-2/3 the initial dose when the client is euthyroid.
Thyrotoxic crisis.
Adults: 200-400 mg q 4 hr during the first day as an adjunct to other treatments.
Neonatal thyrotoxicosis.
10 mg/kg daily in divided doses. |
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