Anastrozole

What it is and how it works

Mechanism of Action The growth of many cancers of the breast is stimulated or maintained by estrogens. In postmenopausal women, estrogens are mainly derived from the action of the aromatase enzyme, which converts adrenal androgens (primarily androstenedione and testosterone) to estrone and estradiol. The suppression of estrogen biosynthesis in peripheral tissues and in the cancer tissue itself can therefore be achieved by specifically inhibiting the aromatase enzyme. Anastrozole is a selective non-steroidal aromatase inhibitor. It significantly lowers serum estradiol concentrations and has no detectable effect on formation of adrenal corticosteroids or aldosterone.

Mechanism class: Aromatase Inhibitors

Indications

Anastrozole is an aromatase inhibitor indicated for: • Adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer ( Error! Hyperlink reference not valid. ) • First-line treatment of postmenopausal women with hormone receptor-positive or hormone receptor unknown locally advanced or metastatic breast cancer ( Error! Hyperlink reference not valid. ) • Treatment of advanced breast cancer in postmenopausal women with disease progression following tamoxifen therapy. Patients with ER-negative disease and patients who did not respond to previous tamoxifen therapy rarely responded to Anastrozole ( Error! Hyperlink reference not valid. ) Adjuvant Treatment Anastrozole is indicated for adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer. First-Line Treatment Anastrozole is indicated for the first-line treatment of postmenopausal women with hormone receptor-positive or hormone receptor unknown locally advanced or metastatic breast cancer.

Dosage and administration (summary)

One 1 mg tablet taken once daily Recommended Dose The dose of anastrozole is one 1 mg tablet taken once a day. For patients with advanced breast cancer, anastrozole tablets should be continued until tumor progression.Anastrozole tablets can be taken with or without food. For adjuvant treatment of early breast cancer in postmenopausal women, the optimal duration of therapy is unknown. In the ATAC trial, anastrozole was administered for five years . No dosage adjustment is necessary for patients with renal impairment or for elderly patients . Patients with Hepatic Impairment No changes in dose are recommended for patients with mild-to-moderate hepatic impairment.

Contraindications

• Patients with demonstrated hypersensitivity to anastrozole tablets or any excipient ( Error! Hyperlink reference not valid. ) Hypersensitivity Anastrozole is contraindicated in any patient who has shown a hypersensitivity reaction to the drug or to any of the excipients. Observed reactions include anaphylaxis, angioedema, and urticaria .

Warnings and precautions

• In women with pre-existing ischemic heart disease, an increased incidence of ischemic cardiovascular events occurred with anastrozole tablets use compared to tamoxifen use. Consider risks and benefits. ( Error! Hyperlink reference not valid. , Error! Hyperlink reference not valid. ) • Decreases in bone mineral density may occur. Consider bone mineral density monitoring. ( Error! Hyperlink reference not valid. , Error! Hyperlink reference not valid. ) • Increases in total cholesterol may occur. Consider cholesterol monitoring. ( Error! Hyperlink reference not valid.

Pregnancy

Pregnancy Risk Summary Based on findings from animal studies and its mechanism of action, anastrozole may cause fetal harm when administered to a pregnant woman [ see Error! Hyperlink reference not valid. ]. There are no studies of anastrozole use in pregnant women.

Storage and supply

Storage Store at 20°to 25°C (68°to 77°F) .

Source: Anastrozole Tablets (Anastrozole) — US FDA prescribing information, 2025-09-01, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.