Comparative Pharmacology
Head-to-head clinical analysis: LEVOTHYROXINE versus THYROLAR 0 25.
Peer-Reviewed Evidence
Head-to-head clinical analysis: LEVOTHYROXINE versus THYROLAR 0 25.
Levothyroxine vs THYROLAR-0.25
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Levothyroxine is a synthetic form of thyroxine (T4) that is converted to triiodothyronine (T3) in peripheral tissues. T3 binds to thyroid hormone receptors in the nucleus, regulating gene transcription and increasing metabolic rate, protein synthesis, and oxygen consumption.
Thyroid hormone (liothyronine, L-triiodothyronine or T3) binds to thyroid hormone receptors in the nucleus, altering gene transcription and protein synthesis, leading to increased metabolic rate, oxygen consumption, and thermogenesis.
1.6 mcg/kg orally once daily, adjusted based on TSH levels; typical adult dose 50-200 mcg/day.
Oral, 0.25 mg (1 tablet) once daily; adjust based on TSH response.
None Documented
None Documented
Clinical Note
moderateLevothyroxine + Sulfisoxazole
"The metabolism of Sulfisoxazole can be decreased when combined with Levothyroxine."
Clinical Note
moderateLevothyroxine + Erythromycin
"The metabolism of Erythromycin can be decreased when combined with Levothyroxine."
Clinical Note
moderateLevothyroxine + Cyclosporine
"The metabolism of Cyclosporine can be decreased when combined with Levothyroxine."
Clinical Note
moderateLevothyroxine + Fluconazole
7 days (euthyroid); prolonged in hyperthyroidism (3-4 days) and shortened in hypothyroidism (9-10 days); clinical effects persist for weeks after discontinuation due to slow elimination.
Levothyroxine (T4): ~7 days; liothyronine (T3): ~1 day. Clinical context: Steady-state achieved in ~5 weeks for T4; T3 half-life shorter leads to more frequent dosing if used alone.
Primarily renal (approximately 50% as unchanged drug and metabolites, mainly glucuronide and sulfate conjugates); minor biliary/fecal excretion (<20%).
Renal: ~40% as conjugated metabolites (glucuronides and sulfates); fecal: ~20% via bile; minor biliary elimination of parent drug (<5%). Total renal clearance of iodine: ~30%.
Category A/B
Category C
Thyroid Hormone
Thyroid Hormone
"The metabolism of Fluconazole can be decreased when combined with Levothyroxine."