Anastrozole 1 mg Tablets – Aromatase Inhibitor for Breast Cancer Treatment in Postmenopausal Women

What is Anastrozole 1 mg?

Anastrozole is a non-steroidal aromatase inhibitor primarily used in the treatment of hormone receptor-positive breast cancer in postmenopausal women.

Mechanism of Action

Estrogen can promote the growth of breast cancer cells. In postmenopausal women, most estrogen is produced by the conversion of androgens into estrogens via the aromatase enzyme.

Anastrozole works by:

• Inhibiting the aromatase enzyme.
• Reducing estrogen levels in the body.
• Slowing or stopping the growth of estrogen-sensitive breast tumors.

Indications and Uses

Anastrozole 1 mg is approved for:

1. Adjuvant treatment of hormone receptor-positive early breast cancer in postmenopausal women.
2. First-line treatment of hormone receptor-positive or hormone receptor-unknown advanced or metastatic breast cancer in postmenopausal women.
3. Treatment of advanced breast cancer after disease progression following tamoxifen therapy.
4. Off-label uses:
   • Management of gynecomastia in men.
   • Polycystic Ovary Syndrome (PCOS) – investigational.
   • To control estrogen in transgender hormone therapy.
   • Infertility treatment in men (e.g., to raise testosterone).

Dosage and Administration

• Standard dose: 1 mg orally once daily.
• With or without food.
• Taken at the same time each day for best effect.
• Duration depends on the clinical scenario, typically 5 years or more for early-stage breast cancer.

Side Effects

Common Side Effects:

• Hot flashes
• Joint or muscle pain (arthralgia)
• Fatigue
• Nausea
• Headache
• Osteoporosis or bone thinning
• Vaginal dryness or irritation
• Mood changes or depression

Serious Side Effects:

• Severe osteoporosis or fractures
• Cardiovascular events (e.g., increased cholesterol)
• Liver enzyme abnormalities
• Allergic reactions (rare)
• Carpal tunnel syndrome

Warnings and Precautions

• Bone Health: Increased risk of bone loss; regular bone density monitoring is recommended.
• Cardiovascular Risk: May raise cholesterol levels; lipid profiles should be monitored.
• Liver function: Use cautiously in those with liver impairment.
• Not for premenopausal women unless specifically indicated.
• Pregnancy: Contraindicated – Category X (teratogenic effects).
• Menopause confirmation: Should be used only after menopause is confirmed in women.

Drug Interactions

• Estrogen-containing medications (e.g., hormone replacement therapy) may reduce the effectiveness of anastrozole.
• Caution with medications affecting liver enzymes (CYP450), though significant interactions are rare.

Monitoring During Treatment

Patients on Anastrozole 1 mg typically require:

• Bone mineral density scans (DEXA)
• Liver function tests
• Lipid panels
• Regular cancer screenings/follow-ups

Storage and Handling

• Store at room temperature (20°C to 25°C / 68°F to 77°F).
• Keep in a dry place away from light and moisture.
• Keep out of reach of children.

Patient Counseling Tips

• Take at the same time every day.
• Inform your doctor about any bone pain, unusual bleeding, or signs of depression.
• Avoid using estrogen products while on anastrozole.
• Engage in weight-bearing exercise and consider calcium + vitamin D supplements to support bone health.