A 62-year-old postmenopausal woman with hormone receptor-positive metastatic breast cancer is started on anastrozole. The mechanism of action of anastrozole is best described as:

• A Inhibition of aromatase, blocking peripheral conversion of androgens to estrogens ✓
• B Selective estrogen receptor downregulation (SERD) in breast tissue
• C Competitive antagonism at estrogen receptors with partial agonist activity
• D Suppression of ovarian estrogen production via negative feedback on the hypothalamus

Explanation

Anastrozole is an aromatase inhibitor that blocks the peripheral conversion of adrenal androgens (androstenedione and testosterone) to estrogens, primarily in adipose tissue. It is used in postmenopausal women where estrogen derives mainly from peripheral aromatization, not ovarian production. SERDs include fulvestrant. SERMs include tamoxifen. Suppressing ovarian production is the role of GnRH agonists, which are used in premenopausal women. Ovarian aromatase is less sensitive to anastrozole.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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