Drug reference
Hyperthyroidism ▶BY MOUTH ▶Adult: Initially 200–400 mg daily in divided doses until the patient becomes euthyroid, then reduced to 50–150 mg daily in divided doses, initial dose should be gradually reduced to the maintenance dose DOSE EQUIVALENCE AND CONVERSION ▶When substituting, carbimazole 1 mg is considered equivalent to propylthiouracil 10 mg but the dose may need adjusting according to response.
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→Appendix 1: propylthiouracil
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▶Rare or very rare Agranulocytosis. bone marrow disorders . glomerulonephritis acute. hearing impairment. leucopenia. thrombocytopenia. vomiting ▶Frequency not known Alopecia. arthralgia. arthritis. encephalopathy. fever. gastrointestinal disorder. haemorrhage. headache. hepatic disorders. hypoprothrombinaemia. interstitial pneumonitis. lupus- like syndrome. lymphadenopathy. myopathy. nausea. nephritis. skin reactions. taste altered. vasculitis SIDE-EFFECTS, FURTHER INFORMATION Severe hepatic reactions have been reported, including fatal cases and cases requiring liver transplant—discontinue if significant liver-enzyme abnormalities develop.
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Propylthiouracil can be given but the blocking-replacement regimen is not suitable. Propylthiouracil crosses the placenta and in high doses may cause fetal goitre and hypothyroidism—the lowest dose that will control the hyperthyroid state should be used (requirements in Graves’ disease tend to fall during pregnancy).
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Present in breast milk but this does not preclude breast-feeding as long as neonatal development is closely monitored and the lowest effective dose is used. Amount in milk probably too small to affect infant; high doses may affect neonatal thyroid function. Monitoring Monitor infant’s thyroid status. Endocrine system
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Manufacturer advises caution (risk of increased half life). Dose adjustments Manufacturer advises consider dose reduction.
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Dose adjustments Use three-quarters normal dose if eGFR 10–50 mL/minute/1.73 m2. Use half normal dose if eGFR less than 10 mL/minute/1.73 m2.
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Monitor for hepatotoxicity.
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There can be variation in the licensing of different medicines containing the same drug. Forms available from special-order manufacturers include: oral suspension, oral solution Tablet ▶Propylthiouracil (Non-proprietary) Propylthiouracil 50 mg Propylthiouracil 50mg tablets | 56 tablet P £57.58 DT = £9.67 | 100 tablet P £17.27–£115.98 VITAMINS AND TRACE ELEMENTS
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Patients should be told how to recognise signs of liver disorder and advised to seek prompt medical attention if symptoms such as anorexia, nausea, vomiting, fatigue, abdominal pain, jaundice, dark urine, or pruritus develop.
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Initially 200–400 mg daily in divided doses until
First-line fragment. Read the complete Indications and Dose section above.
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