Propylthiouracil

Administration

• Type: Antithyroid
• Dosage Forms:
• Routes of Administration:
• Other common names: PTU

Adult Dosing

• Thyroid storm: 500-1000mg PO loading dose, followed by 250mg PO q4h
• Hyperthyroidism
  • Initial: 50-300mg PO TID (based on severity)
  • Maintenance: 50mg PO TID
  • 1st trimester pregnancy: Use lowest dose needed to keep maternal total T3/T4 slightly above normal range for pregnancy, TSH suppressed, and free T4 at or slightly above upper limit of normal for nonpregnant women. Switch to methimazole for 2nd-3rd trimester

Pediatric Dosing

• >6yo: 50 mg PO daily, carefully uptitrated

Special Populations

• Pregnancy Rating: D - see dosing note above
• Lactation risk: Infant risk cannot be ruled out
• Renal dosing: No adjustment
• Hepatic dosing:

Contraindications

• Allergy to class/drug

Adverse Reactions

Serious

Both PTU and methimazole can cause agranulocytosis and hepatotoxicity, but to a lesser extent with methimazole

• Agranulocytosis, aplastic anemia
• Hepatotoxicity, liver failure
• Nephritis
• Vasculitis

Common

• Rash

Pharmacology

• Half-life: 0.9-4.3h
• Metabolism: Hepatic
• Excretion: Renal

Mechanism of Action

• Inhibits thyroperoxidase, blocking thyroid hormone synthesis in the thyroid. In target tissues, blocks 5'-deiodinase, thereby inhibiting conversion of T4 to active T3

Indications by Condition

The following table is automatically generated from disease/condition pages across WikEM.

Indication	Dose	Context	Route	Population
Thyroid storm	500-1000 mg PO/NG load, then 250 mg PO q4h	Thionamide (preferred, also blocks T4→T3)	PO/NG	Adult

See Also

• Hyperthyroidism, thyroid storm
• Methimazole