Propylthiouracil (PTU)

Pregnancy & gynaecology-specific. Every dose row is source-referenced; verify against institutional protocols.

Propylthiouracil (PTU)Antithyroid agent

Regimens checked: 2026-10-17. Each indication has its own preparation, limits and safety checks.

Propylthiouracil (PTU): indication-specific regimens
Indication	Dose	Route	Frequency	Duration / preparation	Maximum	Monitoring / cautions
Overt hyperthyroidism requiring antithyroid medication; preferred early-pregnancy option when appropriate Wockhardt / emcchecked	Product adult initial range 300–600 mg/day in divided doses until controlled; then usually 50–150 mg/day. In pregnancy use the lowest effective dose, individually selected from FT4 and severity, rather than automatically starting at the upper adult range	Oral	Divide the prescribed daily dose, commonly every 8 hours	Titrate with specialist follow-up; if still needed beyond 20 weeks consider changing to carbimazole because of PTU hepatotoxicity · 50 mg tablets; prescribe the exact mg per administration. Do not confuse the outpatient dose with the separate thyroid-storm loading regimen RCOG: use the lowest dose maintaining FT4 in the upper half of its pregnancy range; do not titrate to a suppressed TSH alone. Do not use routine block-and-replace. Renal / hepatic: SmPC: GFR 10–50 mL/min use 75% dose; GFR <10 use 50%; reduce in hepatic disease with specialist review.	600 mg/day is the top of the cited adult starting range, not a routine pregnancy target or an instruction to escalate without endocrine review	Monitor FT4/TSH every 2–4 weeks initially; urgent CBC for fever/sore throat; liver assessment for jaundice, dark urine or abdominal pain Contraindications / cautions Previous PTU-associated hepatic injury/agranulocytosis; significant liver disease requires specialist choice
ICU/endocrine-led treatment of storm from increased hormone synthesis; assess pregnancy stage and hepatic function Society for Endocrinology / BTA / ETA joint consensus, Taylor et al.checked	500–1000 mg loading, then 250 mg every 4 hours	Oral or NG through a protected airway	Load once, then every 4 hours	Acute high-dose treatment only; reduce promptly as the patient stabilises, with an explicit endocrine maintenance plan · 50 mg tablets: loading 10–20 tablets, maintenance 5 tablets per dose; pharmacy-assisted NG preparation if needed. Record administration before starting iodine 2026 joint statement: no proven mortality advantage over methimazole/carbimazole; drug selection must consider hepatic injury and pregnancy.	One initial load; 1500 mg/day maintenance at 250 mg every 4 h. No repeated loading without specialist reassessment	Monitor Continuous cardiac/haemodynamic monitoring, temperature, mental state, glucose, FT4/FT3 and liver function; treat the precipitant Contraindications / cautions Significant hepatic dysfunction/previous PTU liver injury favours an alternative thionamide with endocrine/hepatology input; destructive thyroiditis needs a different strategy

Pregnancy safety

Lowest effective dose; pregnancy timing and hepatic risk determine choice

Lactation

Discuss maternal dose and infant monitoring using RCOG guidance

Wockhardt / emccheckedIN REVIEW