About Anastrozole

Mechanism of Action: Anastrozole is a non-steroidal, reversible aromatase inhibitor that selectively inhibits the aromatase enzyme, reducing the peripheral conversion of androgens (testosterone and androstenedione) into estrogens (estradiol and estrone). This leads to a decrease in circulating estrogen levels.

Indications & Off-Label Uses: FDA-approved for adjuvant treatment of hormone receptor–positive breast cancer in postmenopausal women. Off-label uses include management of estrogen-related side effects in men on testosterone therapy (e.g., gynecomastia, water retention, or elevated estradiol levels), and in certain infertility protocols to modulate estrogen feedback and increase gonadotropin release.

FDA Status: Approved for use in postmenopausal women with hormone receptor–positive breast cancer. All use in men and for hormonal optimization or side effect management is off-label.

Clinical Evidence: Strong evidence supports its efficacy in reducing recurrence and progression of estrogen receptor–positive breast cancer in postmenopausal women. In men on testosterone therapy, smaller clinical studies and extensive clinical experience suggest it effectively lowers estradiol levels and may improve estrogen-related symptoms, though optimal dosing strategies, long-term safety, and effects on cardiovascular and bone health in this population are less well established.

Safety & Monitoring: Common side effects include arthralgia, decreased bone mineral density, hot flashes, fatigue, and potential adverse lipid profile changes. In men, overly aggressive estrogen suppression may negatively impact libido, mood, and bone health. Monitoring may include estradiol levels (sensitive assay), testosterone levels, lipid panel, liver function tests, and bone density assessment in long-term use.