The propylthiouracil dilemma

Area of Science:

• Endocrinology
• Hepatology
• Pharmacovigilance

Background:

• Propylthiouracil (PTU) is an antithyroid medication used to treat hyperthyroidism.
• Hepatotoxicity is a known, albeit rare, adverse effect associated with PTU.
• Recent analyses highlight the need for updated clinical guidance regarding PTU use.

Purpose of the Study:

• To re-evaluate PTU-related hepatotoxicity using FDA data (1982-2008).
• To analyze severe liver adverse events in pediatric, adult, and pregnant patients treated with PTU.
• To propose updated recommendations for the clinical application of PTU.

Main Methods:

• Reanalysis of medical files reporting acute liver failure in PTU-treated patients.
• Specific analysis of pediatric cases (13 files), nonpregnant adult cases (17 files), and pregnant cases (2 files).
• Review of PTU dosage, treatment duration, and timing of liver injury.

Main Results:

• High daily PTU doses (mean 300 mg/day) were observed in pediatric cases.
• Prolonged PTU treatment (≥4 months) was common in pediatric (75%) and adult (64%) patients experiencing liver injury.
• Liver injury in adults often occurred after extended treatment periods (4 months to over 1 year).

Conclusions:

• PTU should be avoided in children; methimazole (MMI) is the preferred alternative.
• In adults, PTU use should be limited to specific cases like Graves' disease without alternatives or thyroid storm.
• During pregnancy, PTU is preferred early on, with potential switching to MMI later; the utility of liver function monitoring for preventing severe PTU hepatotoxicity remains uncertain.