Anastrazole

1. Introduction

Anastrozole, commonly marketed under the brand name Arimidex, is a nonsteroidal aromatase inhibitor used primarily in the treatment of hormone receptor-positive breast cancer. It works by lowering oestrogen levels in postmenopausal women, thereby slowing the growth of hormone-sensitive tumours.

2. Indications

  • Approved Indications:
    • Treatment of hormone receptor-positive early breast cancer in postmenopausal women.
    • First-line treatment of hormone receptor-positive or hormone receptor-unknown advanced breast cancer in postmenopausal women.
    • Treatment of advanced breast cancer in postmenopausal women after tamoxifen failure.
  • Off-Label Uses:
    • Ovulation induction in women with infertility.

3. Dosage

  • Standard Dose: 1 mg once daily.
  • No dosage adjustment is required for elderly patients or those with mild-to-moderate renal or hepatic impairment.

4. Administration

  • Administer orally once daily, with or without food.
  • Swallow the tablet whole with water.

5. Forms Available

  • Tablets: 1 mg.

6. Side Effects

6.1. Common Side Effects

  • Hot flushes.
  • Nausea.
  • Arthralgia (joint pain).
  • Fatigue.
  • Headache.

6.2. Less Common Side Effects

  • Bone pain.
  • Hair thinning or alopecia.
  • Rash.

6.3. Rare but Serious Side Effects

  • Osteoporosis or fractures.
  • Increased cholesterol levels.
  • Hepatotoxicity.

7. Warnings

  • Contraindicated in premenopausal women and in patients with known hypersensitivity to anastrozole.
  • Avoid use during pregnancy and lactation due to risk of foetal harm.
  • Increased risk of bone fractures due to decreased bone mineral density.

8. Precautions

  • Monitor bone health regularly, especially in patients with osteoporosis or risk factors for fractures.
  • Use with caution in patients with severe hepatic impairment.
  • Monitor lipid levels periodically in patients with hypercholesterolaemia.

9. Interactions

  • Drug-Drug Interactions:
    • Avoid concomitant use with tamoxifen, as it may reduce the efficacy of anastrozole.
  • Drug-Food Interactions:
    • No significant food interactions.

10. Monitoring Parameters

  • Bone mineral density (BMD) at baseline and periodically.
  • Lipid profile during treatment.
  • Liver function tests (if clinically indicated).

11. Use in Children

  • Safety and efficacy have not been established in paediatric populations.

12. Use in Pregnancy

  • Contraindicated (Category X).
  • Anastrozole may cause foetal harm; not to be used in women of reproductive potential who are not using contraception.

13. Use in Elderly

  • No dosage adjustment required.
  • Regular monitoring of bone health is essential due to increased fracture risk.

14. Use in Kidney Disease

  • No dosage adjustment required in mild-to-moderate renal impairment (creatinine clearance ≥20 mL/min).
  • Use with caution in severe renal impairment.

15. Use in Liver Disease

  • No dosage adjustment required for mild-to-moderate hepatic impairment.
  • Use with caution in severe hepatic impairment, and monitor liver function.

16. Patient Counselling Points

  • Inform patients about the risk of osteoporosis and the importance of regular bone health monitoring.
  • Advise on potential side effects like hot flushes and joint pain.
  • Highlight the importance of adhering to the prescribed dosage and reporting unusual symptoms (e.g., persistent bone pain).
  • Emphasise that the medication is not suitable for premenopausal women or during pregnancy.

17. Table of Brand Names, Manufacturers, and Prices

Brand NameManufacturerPrice (USD)
ArimidexAstraZeneca$150 (30 tablets, 1 mg)
Generic OptionsVarious$30–50 (30 tablets, 1 mg)

18. FAQs (15 Questions)

  1. What is anastrozole used for?
    Anastrozole is used to treat hormone receptor-positive breast cancer in postmenopausal women.
  2. How does anastrozole work?
    It inhibits the aromatase enzyme, reducing oestrogen levels and slowing tumour growth.
  3. Can anastrozole be taken with food?
    Yes, it can be taken with or without food.
  4. What are the common side effects of anastrozole?
    Hot flushes, joint pain, and fatigue are common side effects.
  5. Are there any serious side effects?
    Yes, osteoporosis, fractures, and increased cholesterol levels are possible.
  6. Can premenopausal women take anastrozole?
    No, it is not suitable for premenopausal women.
  7. Can anastrozole be used during pregnancy?
    No, it is contraindicated due to the risk of foetal harm.
  8. How should anastrozole be stored?
    Store at room temperature, away from moisture and heat.
  9. What happens if I miss a dose?
    Take it as soon as you remember, but skip it if it’s near the next dose. Do not double the dose.
  10. Can I drink alcohol while taking anastrozole?
    Alcohol does not directly interact with anastrozole, but it may exacerbate side effects like fatigue.
  11. Does anastrozole cause hair loss?
    Hair thinning is a possible but uncommon side effect.
  12. Is anastrozole safe for elderly patients?
    Yes, but bone health monitoring is particularly important.
  13. Does anastrozole affect bone health?
    Yes, it can decrease bone mineral density, increasing the risk of fractures.
  14. Can anastrozole interact with tamoxifen?
    Yes, tamoxifen may reduce the effectiveness of anastrozole.
  15. Do I need regular tests while taking anastrozole?
    Yes, bone density and lipid profile should be monitored periodically.