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Propylthiouracil
From WikEM
Contents
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
- 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
