Comparative Pharmacology
Head-to-head clinical analysis: LEVOTHYROXINE versus LEVOXYL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: LEVOTHYROXINE versus LEVOXYL.
Levothyroxine vs LEVOXYL
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.
Levothyroxine is a synthetic thyroid hormone (T4) that is deiodinated to triiodothyronine (T3) in peripheral tissues, binding to thyroid hormone receptors in the nucleus and increasing metabolic rate, protein synthesis, and oxygen consumption.
1.6 mcg/kg orally once daily, adjusted based on TSH levels; typical adult dose 50-200 mcg/day.
Initial adult dose: 25-50 mcg orally once daily; titrate by 12.5-25 mcg every 6-8 weeks based on TSH. Maintenance dose: 50-200 mcg orally once daily.
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.
6-7 days in euthyroid patients; prolonged in hypothyroidism (9-10 days), shortened in hyperthyroidism (3-4 days); clinical steady-state after 6-8 weeks of consistent dosing.
Primarily renal (approximately 50% as unchanged drug and metabolites, mainly glucuronide and sulfate conjugates); minor biliary/fecal excretion (<20%).
Renal (30-50% as unchanged drug and conjugates); fecal (biliary, 20-40% as conjugates); total clearance approximates 1-2 L/day in euthyroid patients.
Category A/B
Category C
Thyroid Hormone
Thyroid Hormone
"The metabolism of Fluconazole can be decreased when combined with Levothyroxine."