Letrozole, an aromatase inhibitor, is used as an off-label medical treatment for endometriosis. What is its mechanism of action in this context?

• A Suppresses pituitary gonadotropin secretion, creating a hypoestrogenic state
• B Inhibits cyclooxygenase-2, reducing prostaglandin-mediated pain in endometriosis
• C Binds to progesterone receptors and induces decidualization of endometriotic tissue
• D Blocks aromatase enzyme in endometriotic lesions, reducing local estrogen production within the implants ✓

Explanation

Letrozole inhibits the aromatase enzyme, which converts androgens to estrogens. Endometriotic lesions aberrantly express aromatase (unlike normal endometrium), enabling local estrogen production. Letrozole reduces this local estrogen synthesis within implants, suppressing lesion growth and pain. It is used off-label, often combined with progestins or OCPs. Option A describes GnRH agonist action. Option C describes progestin action.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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