Comparative Pharmacology
Head-to-head clinical analysis: ANASTROZOLE versus FEMARA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: ANASTROZOLE versus FEMARA.
ANASTROZOLE vs FEMARA
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Anastrozole is a selective non-steroidal aromatase inhibitor. It inhibits the conversion of androgens to estrogens in peripheral tissues, thereby reducing circulating estradiol levels. It has no intrinsic progestogenic, androgenic, or estrogenic activity.
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: ~46 hours (range 30–60 hours). Clinically, steady-state reached after ~10 days; once-daily dosing maintains therapeutic concentrations.
Clinical Note
moderateAnastrozole + Digoxin
"Anastrozole may decrease the cardiotoxic activities of Digoxin."
Clinical Note
moderateAnastrozole + Digitoxin
"Anastrozole may decrease the cardiotoxic activities of Digitoxin."
Clinical Note
moderateAnastrozole + Deslanoside
"Anastrozole may decrease the cardiotoxic activities of Deslanoside."
Clinical Note
moderateAnastrozole + Acetyldigitoxin
"Anastrozole may decrease the cardiotoxic activities of Acetyldigitoxin."
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 (85%): N-dealkylation, hydroxylation, and glucuronidation. Renal excretion of metabolites: ~10% unchanged drug in urine. Fecal elimination: ~10% as metabolites.
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 D/X
Category C
Aromatase Inhibitor
Aromatase Inhibitor