Liothyronine

Category: hormone

Aliases: T3, Cytomel, 3,3′,5-Triiodothyronine

Pharmacological Mechanism

Active thyroid hormone — ~4× more potent than T4 but ~10% the plasma half-life. Binds nuclear TRα/TRβ to regulate metabolic rate, heart rate, thermogenesis. T4 → T3 conversion occurs in peripheral tissues via deiodinases (selenium-dependent). Direct T3 replacement bypasses deiodinase variability.

Half-Life (t½)

PO: 24h, IV: 24h

Dosing Guidelines

• PO: Typical 41.7mcg (Range: 25 - 75 mcg)
• IV: Typical 41.7mcg (Range: 25 - 75 mcg)

Target Organ Systems

• endocrine

Interactions

• Selenium
• Iodine
• Levothyroxine