Overview
Anastrozole is a nonsteroidal aromatase inhibitor used primarily in the treatment of hormone receptor-positive breast cancer in postmenopausal women. It works by reducing estrogen production, which can slow or stop the growth of certain types of breast tumors that require estrogen to grow.
Mechanism of Action
Anastrozole is a selective, nonsteroidal aromatase inhibitor. It inhibits the enzyme aromatase, which converts androgens (androstenedione and testosterone) to estrogens (estrone and estradiol) in peripheral tissues. By reducing circulating estrogen levels, it deprives estrogen-dependent breast cancer cells of the hormonal stimulation needed for growth.
Indications
- 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
Dosage
The recommended dose is 1 mg orally once daily. For adjuvant treatment, duration is typically 5 years. For advanced breast cancer, treatment continues until tumor progression. May be taken with or without food.
Contraindications
- Pregnancy
- Patients with demonstrated hypersensitivity to anastrozole or any components of the formulation
- Premenopausal women
- Patients with severe hepatic impairment
Side Effects
- Hot flashes
- Arthralgia (joint pain)
- Asthenia (weakness)
- Mood disturbances
- Nausea
- Headache
- Back pain
- Insomnia
- Increased cholesterol
- Vaginal dryness
- Rash
- Peripheral edema
Interactions
- Estrogen-containing therapies may diminish therapeutic effect
- Tamoxifen may reduce anastrozole plasma concentrations
- No clinically significant interactions with warfarin or cimetidine observed in clinical studies