Letoval (Letrozole)
Also sold as: Letoval, Femara, Femistra, Letroz, Ovalet
Pregnancy
Cat X
Lactation
Avoid
Schedule
H
Forms
Tablet 2.5mg
Indications
- Breast cancer — hormone receptor-positive (HR+) postmenopausal: adjuvant, extended adjuvant, first-line advanced (primary AI)
- Ovulation induction in PCOS/anovulatory infertility (off-label in India but now WHO recommended first-line over clomiphene — PCOSACT trial)
- Fertility preservation (ovarian stimulation before chemotherapy)
Adult Dosing
Breast cancer (adjuvant)
2.5 mg PO once daily for 5 years (postmenopausal women with HR+ breast cancer after surgery)
Can be extended to 10 years (after initial 5 years tamoxifen or 5 years AI) — MA.17R trial data
Breast cancer (advanced/metastatic)
2.5 mg PO once daily
Continue until disease progression or unacceptable toxicity
Ovulation induction (PCOS)
2.5–7.5 mg PO once daily for 5 days (Day 2–6 of cycle)
Start with 2.5 mg; titrate to 5 mg or 7.5 mg if no ovulation. NOW FIRST-LINE OVER CLOMIPHENE in PCOS (higher live birth rate, lower multiple pregnancy rate — PCOSACT trial).
Pediatric Dosing
Fertility use in premenopausal women: specialist supervised
Renal Dose Adjustment
| CrCl / eGFR | Dose Adjustment |
|---|---|
| Any CrCl | No dose adjustment — primarily hepatic metabolism |
Hepatic Adjustment
Mild-moderate: no adjustment. Severe hepatic impairment (Child-Pugh C): use with extreme caution — data limited.
Pregnancy & Lactation
Pregnancy: Category X
ABSOLUTELY CONTRAINDICATED in pregnancy — aromatase inhibitors can cause fetal harm (masculinisation of female fetus). Must confirm not pregnant before each fertility cycle. Despite off-label fertility use, studies show no teratogenicity when inadvertently used (Biljan et al., 2005) — but still avoid.
Lactation: Avoid
Not applicable (primarily used in postmenopausal women for cancer or fertility). Not safe in breastfeeding.
Top Drug Interactions
| Interacting Drug | Effect | Severity |
|---|---|---|
| Tamoxifen | Reduces letrozole plasma levels by ~38% — avoid concurrent use; sequential use is acceptable (tamoxifen then letrozole) | Moderate |
| Oestrogen-containing products | Reduce aromatase inhibitor effect — contraindicated in breast cancer setting | Major |
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Side Effects
Common
- Musculoskeletal pain/arthralgia (very common — 20–30%; aromatase inhibitor class effect)
- Hot flushes
- Fatigue
- Headache
- Nausea
- Peripheral oedema
- Bone loss/osteoporosis (long-term — fracture risk)
- Vaginal dryness/atrophy
- Hypercholesterolaemia
Serious / Discontinue If
- Osteoporosis / fracture (long-term AI use — bone densitometry monitoring; bisphosphonate may be needed)
- Cardiovascular events (slight increase in cardiac events — monitor lipids)
- Liver function abnormalities (rare)
Contraindications
- Premenopausal women (breast cancer indication — unless combined with ovarian suppression)
- Pregnancy
- Oestrogen-containing products (breast cancer indication)
Available Indian Brands
| Brand | Manufacturer | Price (approx) |
|---|---|---|
| Letoval 2.5mg | Sun Pharma | 30 tab ₹185 |
| Femistra 2.5mg | Zydus | 30 tab ₹175 |
| Letroz 2.5mg | Cipla | 30 tab ₹165 |
| Femara 2.5mg | Novartis | 30 tab ₹485 |
Monitoring Required
- Bone density (DEXA scan at baseline and every 1–2 years in breast cancer use)
- Lipid profile
- Liver function tests
- Follicular USS (ovulation induction — Day 10–14 follicle monitoring)
- Luteal phase progesterone (fertility use)
- Musculoskeletal symptom assessment
Patient Counseling Points
- For PCOS/fertility: take for 5 consecutive days early in your menstrual cycle — attend ultrasound scan as instructed
- For breast cancer: take daily at the same time; continue for full 5 years (or as directed) — protects against cancer recurrence
- Joint pain and stiffness are common side effects — regular low-impact exercise and physiotherapy help greatly
- Calcium (1200 mg/day) and vitamin D3 (800–1000 IU/day) are important to protect bones during long-term use
- ⚠️ Absolutely must NOT be taken if pregnant or trying to conceive (except under fertility specialist care)
- Vaginal dryness: water-based lubricants are safe; vaginal oestrogen (low-dose, minimal systemic absorption) may be discussed with your oncologist if needed
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Clinically reviewed by: Dr. Anitha Krishnamurti, DGO, DNB (Obstetrics & Gynaecology), Senior Consultant
Last reviewed: 2026-04-01
References
- PCOSACT Trial (NEJM 2014)
- ASCO Breast Cancer AI Guidelines 2019
- ESHRE PCOS Guidelines 2023
- BNF — Letrozole
- MA.17R Extended Adjuvant Trial (NEJM 2016)