Comparative Pharmacology
Head-to-head clinical analysis: ARIMIDEX versus FEMARA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: ARIMIDEX versus FEMARA.
ARIMIDEX vs FEMARA
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Aromatase inhibitor; inhibits conversion of androgens to estrogens by binding to aromatase enzyme, reducing estrogen levels in tissues.
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.
1 mg orally once daily
2.5 mg orally once daily.
None Documented
None Documented
Terminal elimination half-life ~50 hours (range 30-60 hours); supports once-daily dosing.
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.
Primarily hepatic metabolism via N-dealkylation and glucuronidation; ~80% excreted in feces, <10% unchanged in urine.
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%.
Category C
Category C
Aromatase Inhibitor
Aromatase Inhibitor