Comparative Pharmacology
Head-to-head clinical analysis: PROPYLTHIOURACIL versus TAPAZOLE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROPYLTHIOURACIL versus TAPAZOLE.
PROPYLTHIOURACIL vs TAPAZOLE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Propylthiouracil (PTU) inhibits thyroid peroxidase, thereby blocking the synthesis of thyroid hormones. It also inhibits the peripheral conversion of thyroxine (T4) to triiodothyronine (T3).
Inhibits thyroid peroxidase, thereby blocking the synthesis of thyroid hormones (T3 and T4) and reducing iodine organification and coupling of iodotyrosines.
Oral, 300-600 mg/day in 3 divided doses until euthyroid; then 50-150 mg/day as maintenance.
15-40 mg per day orally in 3 divided doses; maintenance: 5-15 mg per day orally once daily.
None Documented
None Documented
Terminal elimination half-life is 1-2 hours in euthyroid patients, but may be prolonged to 2-5 hours in hyperthyroid patients due to altered metabolism and thyroid status. Clinical effect persists longer than half-life due to inhibition of thyroid peroxidase.
Clinical Note
moderatePropylthiouracil + Clozapine
"The risk or severity of adverse effects can be increased when Propylthiouracil is combined with Clozapine."
Clinical Note
moderateWarfarin + Propylthiouracil
"Warfarin may decrease the anticoagulant activities of Propylthiouracil."
Clinical Note
moderatePhenprocoumon + Propylthiouracil
"Phenprocoumon may decrease the anticoagulant activities of Propylthiouracil."
Clinical Note
moderatePhenindione + Propylthiouracil
3-6 hours; clinically, effects persist longer due to intrathyroidal accumulation.
Primarily renal (approximately 35% as unchanged drug within 24 hours; remainder as inactive metabolites). Minor biliary/fecal elimination (<5%).
Primarily renal, approximately 65% excreted in urine as metabolites and unchanged drug; <10% eliminated in feces via biliary excretion.
Category D/X
Category C
Antithyroid Agent
Antithyroid Agent
"Phenindione may decrease the anticoagulant activities of Propylthiouracil."