Mechanism of Action of Anastrozole in Postmenopausal Women

Molecular Mechanism

• Anastrozole binds reversibly to the heme group of the aromatase enzyme, distinguishing it from steroidal aromatase inhibitors like exemestane that bind irreversibly to the catalytic site, as recommended by the National Comprehensive Cancer Network 1, 2

Critical Population Restriction

• Anastrozole is only effective in postmenopausal women because aromatization of adrenal androgens is not a significant source of estradiol in premenopausal women, according to Praxis Medical Insights 3

Clinical Implications of Mechanism

• By depleting both circulating and intratumoral estrogen levels, anastrozole causes decreased immunoexpression of proliferation markers, and its profound estrogen suppression explains the drug's superior efficacy in hormone receptor-positive breast cancer but also accounts for its adverse effects on bone metabolism, leading to increased bone resorption and fracture risk, as stated by the National Comprehensive Cancer Network 1, 2