1. Introduction
Letrozole is a non-steroidal aromatase inhibitor primarily used in the treatment of hormone receptor-positive breast cancer in postmenopausal women. By inhibiting aromatase, letrozole reduces oestrogen production, which can slow or stop the growth of oestrogen-dependent tumours. It is also used off-label for ovulation induction in infertility treatments.
2. Indications
- Approved Indications:
- Hormone receptor-positive early breast cancer (adjuvant therapy).
- Advanced or metastatic hormone receptor-positive breast cancer.
- Extended adjuvant treatment in postmenopausal women following tamoxifen therapy.
- Off-Label Uses:
- Ovulation induction in women with polycystic ovary syndrome (PCOS) or unexplained infertility.
3. Dosage
- Breast Cancer:
- Early Breast Cancer: 2.5 mg orally once daily for 5 years or as directed.
- Metastatic Breast Cancer: 2.5 mg orally once daily until disease progression.
- Ovulation Induction (Off-Label):
- 2.5–7.5 mg orally once daily for 5 days, starting on day 3 or 5 of the menstrual cycle.
4. Administration
- Take orally with or without food, preferably at the same time each day.
5. Forms Available
- Tablets: 2.5 mg.
6. Side Effects
6.1. Common Side Effects
- Hot flashes.
- Fatigue.
- Nausea.
- Arthralgia (joint pain).
6.2. Less Common Side Effects
- Headache.
- Dizziness.
- Increased sweating.
- Hair thinning or loss.
6.3. Rare but Serious Side Effects
- Osteoporosis or bone fractures.
- Liver enzyme elevation.
- Cardiovascular events (e.g., deep vein thrombosis, stroke).
7. Warnings
- Bone Density: Long-term use may cause bone loss (osteopenia or osteoporosis). Regular bone density monitoring is advised.
- Cardiovascular Risks: Use cautiously in patients with pre-existing cardiovascular disease, as letrozole may increase the risk of thromboembolic events.
- Liver Impairment: Monitor liver function during prolonged use.
8. Precautions
- Avoid use in premenopausal women, except for ovulation induction under specialist care.
- Use cautiously in patients with a history of osteoporosis or fractures.
- Patients should report symptoms of blood clots, such as leg swelling or chest pain, immediately.
9. Interactions
- Drug-Drug Interactions:
- Tamoxifen: May reduce the effectiveness of letrozole. Avoid concurrent use.
- Oestrogen-containing products: Counteracts the effects of letrozole.
- CYP2A6 and CYP3A4 inducers (e.g., phenytoin, rifampin): May reduce letrozole levels.
- Drug-Food Interactions:
- No significant interactions, but consistency in administration is recommended.
10. Monitoring Parameters
- For breast cancer: Regular monitoring of tumour progression (e.g., imaging and tumour markers).
- For ovulation induction: Follicular development using ultrasound and hormonal levels (e.g., oestradiol).
- Bone density (for long-term therapy).
- Liver function tests (during prolonged treatment).
11. Use in Children
- Not recommended due to lack of safety and efficacy data.
12. Use in Pregnancy
- Category X: Contraindicated in pregnancy due to the risk of foetal harm. It is not to be used in pregnant or breastfeeding women.
13. Use in Elderly
- Safe for use, but monitor for side effects such as bone loss and cardiovascular risks.
14. Use in Kidney Disease
- No dose adjustment is required in mild to moderate renal impairment. Use cautiously in severe renal impairment (creatinine clearance <10 mL/min).
15. Use in Liver Disease
- Use with caution in patients with moderate to severe hepatic impairment. Monitor liver function regularly.
16. Patient Counselling Points
- Take letrozole at the same time each day to maintain consistent blood levels.
- Notify your doctor if you experience symptoms like bone pain, severe fatigue, or chest pain.
- For women using letrozole for ovulation induction, monitor closely for signs of ovarian hyperstimulation (e.g., abdominal pain or swelling).
- Avoid pregnancy while on letrozole. Use effective contraception during and after therapy until cleared by your doctor.
- Maintain a diet rich in calcium and vitamin D and consider weight-bearing exercises to reduce the risk of bone loss.
17. Table of Brand Names, Manufacturers, and Prices
Brand Name | Manufacturer | Price (USD) |
---|---|---|
Femara | Novartis | $250–400 (30 tablets, 2.5 mg) |
Generic Letrozole | Various manufacturers | $15–50 (30 tablets, 2.5 mg) |
18. FAQs (15 Questions)
- What is letrozole used for?
Letrozole is used to treat hormone receptor-positive breast cancer and for ovulation induction in infertility. - How does letrozole work?
It inhibits aromatase, reducing oestrogen production and slowing the growth of oestrogen-dependent tumours. - When should I take letrozole?
Take it once daily, at the same time each day, with or without food. - Can letrozole cause side effects?
Yes, common side effects include hot flashes, fatigue, and joint pain. - Is letrozole safe during pregnancy?
No, it is contraindicated due to the risk of foetal harm. - How long should letrozole be taken for breast cancer?
Typically, it is taken for 5 years, but duration may vary based on the patient’s condition. - Can letrozole cause bone loss?
Yes, long-term use may cause bone thinning or osteoporosis. - What should I do if I miss a dose of letrozole?
Take it as soon as you remember, unless it is close to the next dose. Do not double up. - Does letrozole interact with tamoxifen?
Yes, tamoxifen may reduce the effectiveness of letrozole. Avoid concurrent use. - Can letrozole be used in premenopausal women?
Generally no, except under specialist care for ovulation induction. - How is letrozole used for ovulation induction?
It is typically taken for 5 days starting on day 3 or 5 of the menstrual cycle to stimulate ovulation. - Can letrozole cause cardiovascular problems?
Yes, it may increase the risk of thromboembolic events and cardiovascular issues, especially in those with pre-existing conditions. - How should letrozole be stored?
Store at room temperature, away from moisture and heat. - What dietary changes are recommended while taking letrozole?
Increase calcium and vitamin D intake to counteract potential bone loss. - Can letrozole be stopped abruptly?
Stopping without medical advice is not recommended. Consult your doctor before discontinuation.