Propylthiouracil
Mechanism :
Propylthiouracil is an anti-thyroid drug.
Indication :
Contraindications :
Hypersensitivity or idiosyncratic reaction to propylthiouracil.
Dosing :
Neonates:
Initially 5-10 mg/kg/day PO in 8 hourly divided doses.
<6 years: 5-7 mg/kg/day PO in 8 hourly divided doses initially.
6-10 years: 50-100 mg/day PO in 8 hourly divided doses.
>10 years: 150-300 mg/day.
Maintenance:
Generally one-third or two-third of the initial; doses on the basis of response in 8-12 hourly divided doses.
Adverse Effect :
Agranulocytosis is the most serious potential side effect. It usually develops in the first few months of therapy, is dose related and is reversible on rapid withdrawal of the drug.
Leukopenia with granulocytopenia, hemolytic anemia, thrombocytopenia, hypoprothrom- binemia with hemorrhagic manifestations, aplastic anemia, myeloblastic leukemia, hyperglobulinemia, urticaria, pruritus, papular rash, loss or depigmentation of the hair, nausea, vomiting, abdominal discomfort, drowsiness, headache, dizziness, arthralgia and paresthesia occur occasionally. Maternal ingestion in pregnancy can lead to fetal goitre.
Interaction :
Increased sensitivity to warfarin has been observed in hyperthyroidism and careful control of dosage is required as the patient is rendered euthyroid.
Changes in thyroid state may affect response to digoxin, theophylline, beta-blockers and insulin.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function |
| 10-20 | 75% of normal dose and titrate to response |
| <10 | 50% of normal dose and titrate to response |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Unknown dialysability. Dose as in GFR<10 mL/min |
| HD | Not dialysed. Dose as in GFR<10 mL/min |
| HDF/High flux | Unknown dialysability. Dose as in GFR<10 mL/min |
| CAV/VVHD | Unknown dialysability. Dose as in GFR=10–20 mL/min |
Hepatic Dose :
Reconsider the use of propylthiouracil in patients with liver transaminase levels more than 5-fold above the upper limit of normal (ULN). If liver transaminase levels rise by 2 to 3 times ULN during therapy and persist for a week: stop therapy.