Presentation and Status in Health Basket
30 X 50 mg
Note: The total daily dosage is usually given in 3 equal doses at approximately 8- hour intervals. The tablets can be divided. They must not be chewed or crushed.
Adults: Initial Dosage: 200-300 mg daily, in divided doses. In patients with severe hyperthyroidism, very large goiters, or both, the initial dosage should usually be 400 mg daily. An occasional patient may require 600-900 mg/day initially.
Maintenance Dosage: 100-150 mg daily. This may be increased according to the degree of severity of the individual case.
Children 6-10 Years of Age: Initial Dosage 50-150 mg daily.
Maintenance Dosage: The maintenance dosage should be determined according to the response of the patient.
Children over 10 Years of Age: Initial Dosage 150-300 mg daily.
Maintenance Dosage: The maintenance dosage should be determined according to the response of the patient.
Known hypersensitivity to propylthiouracil, related thioamide derivatives, or to any other ingredient of the preparation. Lactation.
NOTE: Severe liver injury and acute liver failure, in some cases fatal, have been reported in patients treated with propylthiouracil. These reports of hepatic reactions include cases requiring liver transplantation in adult and pediatric patients. Propylthiouracil should be reserved for patients who can not tolerate methimazole and in whom radioactive iodine therapy or surgery are not appropriate treatments for the management of hyperthyroidism. Because of the risk of fetal abnormalities associated with methimazole, Propylthiouracil may be the treatment of choice when an antithyroid drug is indicated during or just prior to the first trimester of pregnancy.
Patients who receive propylthiouracil should be under close surveillance. They should be instructed to report immediately any evidence of illness, particularly symptoms such as sore throat, skin eruptions, fever, headache, or general malaise. In such cases, white blood cell and differential counts should be conducted in order to determine whether agranulocytosis has developed. Particular care should be exercised with patients who are receiving additional drugs known to cause agranulocytosis. If serious adverse reactions occur, the drug should be discontinued. Mild reactions may require a reduction of dosage or temporary discontinuation of the drug. It should be noted that mild reactions may precede more serious ones. Since hypoprothrombinemia and bleeding may occur, prothrombin time should be monitored during therapy, especially prior to surgical procedures. Regular thyroid function tests are recommended in patient monitoring (recommended prior to initiation of therapy, at monthly intervals during stabilization, then every 2 to 3 months) viz Free (unbound) serum thyroxine (T4) levels, Total serum T4 levels, Serum thyrotropin (TSH), Total serum triiodothyronine (T3). Liver Function Tests are also recommended at periodic intervals during therapy. Once clinical evidence of hyperthyroidism has resolved, the finding of an elevated serum TSH indicates that a lower maintenance dose of propylthiouracil should be employed. In preparing patients for surgery, the administration of iodine is recommended concomitantly with propylthiouracil to decrease the vascularity and friability of the thyroid gland. Although propylthiouracil is used for the total treatment of hyperthyroidism, duration of treatment necessary to produce prolonged remission varies from 6 months to several years, with an average duration of one year. Remission has occurred in at least 50% of patients 6-12 months after cessation of medication. In view of the fact that hypothyroid patients seem to have poor adrenergic nervous function, use with caution in patients with asthma.
Major adverse reactions, which occur much less often than the minor ones, include liver injury resulting in hepatitis, liver failure, a need for liver transplantation or death, inhibition of myelopoiesis (agranulocytosis, granulopenia and thrombocytopenia) aplastic anemia, drug fever, leukopenia, hypoprothrombinemia, bleeding, vasculitis, nephrotic syndrome, nephritis (unusual increase or decrease in urination, backache, swelling of feet or lower legs), drug fever, lupus-like syndrome, including solenomegaly, periarteritis, and hepatitis. Nephritis, glomerulonephritis, interstitial pneumonitis, exfoliative dermatitis, and erythema nodosum have been reported. Reports of a vasculitic syndrome associated with the presence of anti-neutrophilic cytoplasmic antibodies (ANCA) have also been received. Manifestations of ANCA-positive vasculitis may include rapidly progressive glomerulonephritis (crescentic and pauci-immune necrotizing glomerulonephritis) sometimes leading to acute renal failure; fever; pulmonary infiltrates or alveolar hemorrhage; skin ulcers; and leucocytoclastic vasculitis. Minor side effects such as skin rash, urticaria, nausea, vomiting, epigastric distress, arthralgia, paresthesia, loss of taste, taste perversion, abnormal loss of hair, myalgia, headache, pruritus, drowsiness, neuritis, edema, vertigo, skin pigmentation, jaundice, sialadenopathy, lymphadenopathy (swollen lymph nodes), vasculitis, glomerulonephritis, and joint stiffness may occur. It should be noted that about 10% of patients with untreated hyperthyroidism have leukopenia (white blood cell count of less than 4,000/mm3), often with relative granulopenia.
Propylthiouracil/Anticoagulants/Heparin: The activity of anticoagulants may be potentiated by the antivitamin K activity which is attributed to propylthiouracil. Prothrombin times should be carefully monitored during therapy.
Propylthiouracil/β-Adrenergic Blocking Agents: Hyperthyroidism may cause an increased clearance of beta blockers with a high extraction ratio. A dose reduction of beta-adrenergic blockers may be needed when a hyperthyroid patient becomes euthyroid.
PropylthiouracilTheophylline: Theophylline clearance may decrease when hyperthyroid patients on a stable theophylline regimen become euthyroid; a reduced dose of theophylline may be needed.
Propylthiouracil/Drugs Known to Cause Agranulocytosis: Propylthiouracil should be used with extreme caution in patients receiving other drugs known to cause agranulocytosis (e.g.: sulfonamide antibiotics, clozapine, spironolactone).
Antithyroid Agents/Digitalis Glycosides: It has been reported that, as the thyroid and metabolic status of patients taking antithyroid agents decrease, serum concentrations of digoxin and digitoxin may increase upon concomitant administration. Therefore, a reduction in the digitalis glycoside dosage may be necessary.
Antithyroid Agents/Amiodarone: Amiodarone contains 37% iodine by weight. Concomitant administration may increase the iodine intake, leading to a decrease in response to the antithyroid agent. Therefore, either the dosage of the antithyroid agent should be reduced, or the duration of therapy be longer.
Pregnancy and Lactation
Pregnancy: Propylthiouracil, can cause fetal harm when administered to a pregnant woman. Because the drug readily crosses placental membranes and can induce goiter and even cretinism in the developing fetus, it is important that a sufficient but no excessive, dose be given. In many pregnant women, the thyroid dysfunction diminishes as the pregnancy proceeds; consequently, a reduction of dosage may be possible. In some instances, propylthiouracil can be withdrawn 2 or 3 weeks before delivery. There are cases of liver injury, including liver failure and death, in women treated with propylthiouracil during pregnancy. Two reports of in utero exposure with liver failure and death of a newborn have been reported. The use of an alternative antithyroid medication (e.g., methimazole) may be advisable following the first trimester of pregnancy. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be warned of the potential hazard to the fetus. Postpartum patients receiving propylthiouracil should not nurse their babies. In administering propylthiouracil during pregnancy, careful consideration should be given to the dosage for individual patients to provide the required therapeutic effect compatible with minimum risk to the foetus from potential toxicity. The dose should be set as low as possible since there is evidence that neonatal goitre is less likely if the mother receives less than 100 mg of propylthiouracil per day. After control of thyrotoxicosis, the dose of propylthiouracil should be gradually decreased to 50 mg twice daily. If there is the slightest suspicion of hypothyroidism in the pregnant patient, the drug should be temporarily discontinued and thyroid hormone given. Three cases of scalp defects in the offspring of mothers, and 2 siblings with aplasia cutis in one mother, who were on methimazole, a related thioamide derivative, have been reported.
Breastfeeding: Propylthiouracil appears in breast milk. Therefore, mothers using this medication should not nurse
Manifestations: Nausea, vomiting, epigastric distress, headache, fever, arthralgia, pruritus, edema, pancytopenia. Agranulocytosis is the most serious effect. Rarely, exfoliative dermatitis, hepatitis, neuropathies or CNS stimulation or depression may occur.
Treatment: Treatment of propylthiouracil overdose generally involves symptomatic and supportive care. Following acute overdose of the drug, the stomach should be emptied by inducing emesis or by gastric lavage. Activated charcoal may be considered instead of or in addition to gastric emptying. If the patient is comatose, having seizures, or lacks the gag reflex, gastric lavage may be performed if an endotracheal tube with cuff inflated is in place to prevent aspiration of vomitus. The patient’s airways should be protected, and ventilation and perfusion supported. Patient’s vital signs, blood gases, serum electrolytes, etc. should be meticulously monitored and maintained within acceptable limits. The patient’s bone marrow function should be monitored. Appropriate therapy, possibly including anti-infectives, and transfusion of fresh whole blood should be instituted if bone marrow depression develops. Appropriate therapy, including rest, and adequate diet, should be instituted if hepatitis occurs. Analgesics, sedatives and intravenous fluid may also be indicated in the management of overdose with the drug. Forced diuresis, peritoneal dialysis, hemodialysis or charcoal hemoperfusion have not been established as beneficial for an overdose of propylthiouracil.