Generic
Propylthiouracil
2 brands available in the market
At a glance
Propylthiouracil is an anti-thyroid medication used for hyperthyroidism, particularly in patients with Graves' disease or toxic multinodular goiter who are intolerant of methimazole and for whom surgery or radioactive iodine therapy is not an appropriate treatment option.
Description
Propylthiouracil inhibits the synthesis of thyroid hormones by preventing iodine oxidation in the thyroid gland. It also blocks the peripheral deiodination of thyroxine to tri-iodothyronine, which may be effective in treating thyroid storm.
Indications
- Graves' disease with hyperthyroidism or toxic multinodular goiter (methimazole-intolerant)
- Amelioration of hyperthyroidism symptoms in preparation for thyroidectomy or radioactive iodine therapy (methimazole-intolerant)
Therapeutic class
Thyroid drugs & hormone
Pharmacological class
Anti-thyroid (Thiouracil)
Pharmacology
Propylthiouracil inhibits thyroid hormone synthesis by preventing iodine oxidation in the thyroid gland. It also blocks peripheral deiodination of thyroxine (T4) to tri-iodothyronine (T3), which is effective in severe hyperthyroidism (thyroid storm).
Mechanism of action
Controls hyperthyroidism by inhibiting thyroid hormone synthesis.
Dosage
Adult Dose (Oral):
- Hyperthyroidism: 150-450 mg daily in divided doses; severe cases: 600-1200 mg daily initially; maintenance: 50-150 mg daily
- Hepatic impairment: Dose reduction recommended
- Treatment usually continued for 1-2 years
Pediatric Dose (Oral):
- Neonates: 2.5-5 mg/kg twice daily
- 1 month-1 year: 2.5 mg/kg three times daily
- 1-5 years: 25 mg three times daily
- 5-12 years: 50 mg three times daily
- 12-18 years: 100 mg three times daily
Administration
- May be taken with or without food; take at a fixed time
- Swallow tablet whole; do not chew, crush, or break
Missed dose
If you miss a dose, take it as soon as you remember; skip if it's almost time for next dose; do not double the dose.
Side effects
Side Effects:
- Skin rash
- Urticaria
- Pruritus
- Abnormal hair loss
- Skin pigmentation
- Nausea, vomiting
- Arthralgia
- Myalgia
- Paresthesia
- Headache
- Leukopenia
- Agranulocytosis
- Hepatitis, hepatic failure
Precautions & warnings
- Risk of agranulocytosis; report sore throat, fever, mouth ulcers, malaise immediately
- Severe hepatic reactions (fatal) may occur; occurs within first 6 months; discontinue if liver enzyme abnormalities develop
- Monitor prothrombin time before surgery
- Use lowest possible dose during pregnancy
- Monitor neonatal development during lactation
Contraindications
- Hypersensitivity to propylthiouracil or any component
- Pregnancy
- Lactation
Drug interactions
- Oral anticoagulants (warfarin): Increased PT/INR monitoring
- Beta-blockers: Dose reduction may be needed when euthyroid
- Digitalis glycosides: Dose reduction may be needed when euthyroid
- Theophylline: Dose reduction may be needed when euthyroid
Food interactions
It is not known whether it is safe to consume alcohol with Propylthiouracil.
Use in pregnancy
Use in Pregnancy: Unsafe during pregnancy; may cause fetal goiter and hypothyroidism; use lowest possible dose; consult your doctor.
Pregnancy Category: D — always consult a doctor before taking during pregnancy.
Use in lactation
Use in Lactation: Safe during breastfeeding; small amounts excreted in breast milk; monitor infant development.
Pediatric use
Not generally recommended in pediatric patients; may be used in rare instances; inform parents of risk of liver failure.
Geriatric use
Elderly patients require caution; higher frequency of decreased hepatic, renal, or cardiac function.
Renal / hepatic impairment
Renal Impairment: Safe in kidney disease; dose adjustment may not be needed; CrCl 10-50: reduce dose by 25%; CrCl <10: reduce dose by 50%; consult your doctor.
Hepatic Impairment: Limited information on use in liver disease; caution; dose adjustment may be needed; consult your doctor.
Overdose effects
Overdose: Nausea, vomiting, epigastric distress, headache, fever, arthralgia, pruritus, edema, pancytopenia, agranulocytosis; treatment: supportive care.
Storage conditions
Store in a cool (below 30°C) and dry place, away from light and children.
Chemical structure
Propylthiouracil