Propylthiouracil

Class
Antithyroid agents
Subclass
Thyroid peroxidase inhibitors
Substance name
Propylthiouracil
Common formulations
Tablet
Dosage and administration
Adults patients
Hyperthyroidism in patients with Graves' disease
•
Start at: 300-400 mg PO daily, in 3 divided doses
•
Maintenance: 100-150 mg PO daily, in 3 divided doses
•
Maximum: 600-900 mg per day
Hyperthyroidism in patients with toxic multinodular goiter
•
Start at: 300-400 mg PO daily, in 3 divided doses
•
Maintenance: 100-150 mg PO daily, in 3 divided doses
•
Maximum: 600-900 mg per day
Other off-label uses
•
Treatment of thyroid storm
Indications for use
Labeled indications
Adults
•
Treatment of Graves' disease
•
Treatment of hyperthyroidism in patients with Graves' disease
•
Treatment of hyperthyroidism in patients with toxic multinodular goiter
•
Treatment of thyrotoxicosis
Children
•
Treatment of Graves' disease
Off-label indications
Adults
•
Treatment of thyroid storm
Safety risks
Boxed warnings
Agranulocytosis
•
Use extreme caution with risk factors for bone marrow suppression and those using drugs known to cause agranulocytosis.
Contraindications
A history of hypersensitivity to the drug
Warnings and precautions
Drug-induced liver injury
•
Use caution with pre-existing hepatic disease.
Vasculitis
•
Use caution with risk factors for developing vasculitis.
Specific populations
Renal impairment
eGFR 20-50 mL/min/1.73 m²
•
Use acceptable. No dose adjustment required. Monitor for cardiotoxicity and leucopenia.
eGFR 10-20 mL/min/1.73 m²
•
Reduce dose by 25%. Titrate to response. Monitor for cardiotoxicity and leucopenia.
eGFR < 10 mL/min/1.73 m²
•
Reduce dose by 50%. Titrate to response. Monitor for cardiotoxicity and leucopenia.
Renal replacement therapy
Continuous renal replacement
•
Dose as in eGFR 10-20 mL/min/1.73 m². Reduce dose by 25%. Titrate to response. Monitor for cardiotoxicity and leukopenia.
Intermittent hemodialysis
•
Dose as in eGFR < 10 mL/min/1.73 m². Reduce dose by 50%. Titrate to response. Monitor for cardiotoxicity and leukopenia.
Peritoneal dialysis
•
Dose as in eGFR < 10 mL/min/1.73 m². Reduce dose by 50%. Titrate to response. Monitor for cardiotoxicity and leukopenia.
Hepatic impairment
Any severity
•
Use with caution. Monitor serum aminotransferases. Monitor for toxicity.
Pregnancy and breastfeeding
Pregnancy
All trimesters • Australia Category: C
•
Avoid use. Evidence of fetal harm in humans. US FDA pregnancy category D.
•
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.
•
If propylthiouracil is used during pregnancy, or if the patient becomes pregnant while taking propylthiouracil, the patient should be warned of the rare potential hazard to the mother and fetus of liver damage.
•
Because of the risk of fetal abnormalities associated with methimazole, propylthiouracil (PTU) may be the treatment of choice when an antithyroid drug is indicated during or just prior to the first trimester of pregnancy.
•
Methimazole should be used when antithyroid drug therapy is started after the first trimester unless the patient is allergic or intolerant, as PTU does present health risks to the mother and the exposed fetus. PTU is transferred across the placenta.
Breastfeeding
Acceptable for use during breastfeeding.
Unknown drug levels in breastfed infants.
Unlikely to cause adverse effects in breastfed infants.
Adverse reactions
Very common > 10%
•
↓ WBC count
Common 1-10%
•
Hyperpigmented skin patches, arthralgia, generalized pruritus, skin rash, skin rash, urticaria
Uncommon < 1%
•
Agranulocytosis
Unknown frequency
•
AKI, acute liver failure, acute respiratory distress syndrome, acute interstitial pneumonia, acute otitis media, alopecia, aplastic anemia, arthritis, cholestatic liver disease, coagulation disorder, disseminated intravascular coagulation, ↓ platelet count, ↓ serum calcium, drug-induced liver injury, hypersensitivity vasculitis, immunosuppression, leukemia, nephritis, osteomyelitis, ototoxicity, pneumonia, precocious puberty, pulmonary hemorrhage, dizziness, dysgeusia, fever, galactorrhea, headache, hemoptysis, loss of appetite, malaise, paresthesia, sexual dysfunction, somnolence, vertigo, systemic lupus erythematosus, sensorineural hearing loss, Stevens-Johnson syndrome, thyroid gland abnormality, vasculitis
Interactions
Drug(s)
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