Comparative Pharmacology
Head-to-head clinical analysis: PROPYLTHIOURACIL versus THYROSHIELD.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROPYLTHIOURACIL versus THYROSHIELD.
PROPYLTHIOURACIL vs THYROSHIELD
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).
Thyroshield (potassium iodide) acts by supplying excess iodide, which inhibits thyroid hormone synthesis via the Wolff-Chaikoff effect, blocks thyroidal iodide uptake, and reduces thyroid vascularity. It also protects the thyroid from radioactive iodine uptake by saturating iodine transport and organification mechanisms.
Oral, 300-600 mg/day in 3 divided doses until euthyroid; then 50-150 mg/day as maintenance.
Intravenous: Loading dose 200 mg, then 50 mg every 6 hours; or continuous infusion: 200 mg bolus then 800 mg over 24 hours. Oral: 50 mg every 6 hours.
None Documented
None Documented
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
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.
Terminal elimination half-life is 12-24 hours; clinical effect persists 24-36 hours after single dose.
Primarily renal (approximately 35% as unchanged drug within 24 hours; remainder as inactive metabolites). Minor biliary/fecal elimination (<5%).
Primarily renal (90-95% unchanged), minor biliary/fecal (5-10%).
Category D/X
Category C
Antithyroid Agent
Antithyroid Agent
"Phenindione may decrease the anticoagulant activities of Propylthiouracil."