Formulary
Propylthiouracil: Indications, Dosing, Side Effects and Interactions
Propylthiouracil clinical drug profile including indications, dosing, side effects, cautions and interactions.
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Propylthiouracil: Indications, Dosing, Side Effects and Interactions
Propylthiouracil clinical drug profile including indications, dosing, side effects, cautions and interactions.
Indications and dose
**Hyperthyroidism**
- **Adult** (By Mouth): 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.
**Hyperthyroidism (including Graves' disease) for propylthiouracil**
- **Neonate** (By mouth): Initially 2.5-5 mg/kg twice daily until euthyroid, usually after 8 to 12 weeks, then gradually reduce to a maintenance dose of 30-60% of the initial dose; higher initial doses are occasionally required, particularly in thyrotoxic crisis.
- **Child 1-11 months** (By mouth): Initially 2.5 mg/kg 3 times a day until euthyroid, usually after 4 to 8 weeks, then gradually reduce to a maintenance dose of 30-60% of the initial dose; higher initial doses are occasionally required, particularly in thyrotoxic crisis.
- **Child 1-4 years** (By mouth): Initially 25 mg 3 times a day until euthyroid, usually after 4 to 8 weeks, then gradually reduce to a maintenance dose of 30-60% of the initial dose; higher initial doses are occasionally required, particularly in thyrotoxic crisis.
- **Child 5-11 years** (By mouth): Initially 50 mg 3 times a day until euthyroid, usually after 4 to 8 weeks, then gradually reduce to a maintenance dose of 30-60% of the initial dose; higher initial doses are occasionally required, particularly in thyrotoxic crisis.
- **Child 12-17 years** (By mouth): Initially 100 mg 3 times a day until euthyroid, usually after 4 to 8 weeks, then gradually reduce to a maintenance dose of 30-60% of the initial dose; higher initial doses are occasionally required, particularly in thyrotoxic crisis.
Side effects
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.
Interactions
**Other interactions (3):**
- The response of the thyroid gland to propylthiouracil may be impaired by a concurrent high iodine intake.
- Drug induced changes in thyroid status may affect the dosage requirements for theophylline and digitalis.
- The doses of digitalis and theophylline may need to be reduced as thyroid function returns to normal.
Pregnancy
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).
Breast feeding
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 in breast feeding Monitor infant's thyroid status.
Hepatic impairment
Manufacturer advises caution (risk of increased half life). Dose adjustments Manufacturer advises consider dose reduction.
Renal impairment
Dose adjustments See Prescribing in renal impairment . Use three-quarters normal dose if eGFR 10-50 mL/minute/1.73 m 2 . M Use half normal dose if eGFR less than 10 mL/minute/1.73 m 2 . M
Medicinal forms
Solution
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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