Comparative Pharmacology
Head-to-head clinical analysis: FEMARA versus LETROZOLE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: FEMARA versus LETROZOLE.
FEMARA vs LETROZOLE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Aromatase inhibitor; inhibits the conversion of androgens to estrogens by competitively binding to the aromatase enzyme, thereby reducing estrogen levels in peripheral tissues and tumors.
Letrozole is a nonsteroidal aromatase inhibitor. It inhibits the aromatase enzyme, which converts androgens to estrogens, thereby reducing estrogen levels in postmenopausal women and suppressing estrogen-dependent tumor growth.
2.5 mg orally once daily.
2.5 mg orally once daily
None Documented
None Documented
The terminal elimination half-life of letrozole is approximately 2 days (range 24–48 hours). Steady-state concentrations are achieved within 2–6 weeks of daily dosing. The long half-life supports once-daily dosing.
Clinical Note
moderateLetrozole + Digoxin
"Letrozole may decrease the cardiotoxic activities of Digoxin."
Clinical Note
moderateLetrozole + Digitoxin
"Letrozole may decrease the cardiotoxic activities of Digitoxin."
Clinical Note
moderateLetrozole + Deslanoside
"Letrozole may decrease the cardiotoxic activities of Deslanoside."
Clinical Note
moderateLetrozole + Acetyldigitoxin
"Letrozole may decrease the cardiotoxic activities of Acetyldigitoxin."
Terminal elimination half-life approximately 45 hours (range 42-52 hours). Steady-state achieved in 2-6 weeks with daily dosing.
Letrozole is extensively metabolized in the liver, primarily to an inactive carbinol metabolite. Approximately 90% of an oral dose is excreted in urine, with about 6% as unchanged drug and 84% as metabolites. Fecal excretion accounts for less than 10%.
Primarily hepatic metabolism (CYP3A4, CYP2A6) with 90% excreted in urine as metabolites (glucuronide conjugates) and 10% in feces. <6% excreted unchanged in urine.
Category C
Category D/X
Aromatase Inhibitor
Aromatase Inhibitor