Anastrozole: A Powerful Aromatase Inhibitor
Anastrozole, sold under the brand name Arimidex among others, was initially developed for the treatment of breast cancer in postmenopausal women. However, it's increasingly being used off-label for men to help regulate estrogen levels when undergoing testosterone replacement therapy.
Mechanism of Action
Anastrozole works by inhibiting the enzyme aromatase, which is responsible for converting androgens to estrogens. This effectively lowers estrogen levels in the body, making it an essential component for testosterone replacement therapy in men. Additionally, some foods like grapes, berries, and cruciferous vegetables also contain natural aromatase inhibitors or promote the inhibition of aromatase.
FDA Indications
- Treatment of postmenopausal women with hormone receptor-positive early breast cancer
- Adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer
- First-line treatment of postmenopausal women with hormone receptor-positive or hormone receptor-unknown locally advanced or metastatic breast cancer
- Treatment of advanced breast cancer in postmenopausal women with disease progression following tamoxifen therapy
Off-Label Indications for Men
- Regulation of estrogen levels in men undergoing testosterone replacement therapy
Clinical Evidence
Anastrozole has been well-studied for its FDA-approved indications. However, data for off-label use in men is less robust but increasing, with several studies showing its efficacy in maintaining balanced estrogen levels for men on testosterone therapy.
Side Effects
- Hot flashes
- Joint symptoms (including arthritis and arthralgia)
- Weakness
- Mood changes
Drug Interactions
- Tamoxifen
- Estrogen-containing therapies
Contraindications
- Known hypersensitivity to the drug
- Pre-menopausal women
- Pregnancy and lactation
