A 58-year-old postmenopausal woman with ER-positive breast cancer is started on adjuvant anastrozole. Its mechanism of action is:

• A Competitive blockade of estrogen receptors in breast tissue
• B Acceleration of hepatic estrogen metabolism
• C Suppression of ovarian estradiol synthesis
• D Inhibition of androgen-to-estrogen conversion in peripheral tissues ✓

Explanation

Anastrozole is an aromatase inhibitor that blocks conversion of androgens to estrogens in peripheral tissues such as adipose and muscle. In postmenopausal women, this is the dominant source of estrogen. Receptor blockade describes tamoxifen. Ovarian suppression is irrelevant after menopause, as the ovaries no longer produce significant estrogen. Aromatase inhibitors do not accelerate hepatic metabolism.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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