Generic
Letrozole
17 brands available in the market
At a glance
Letrozole is used for the treatment of breast cancer in postmenopausal women and infertility due to anovulation. It is an aromatase inhibitor that decreases the amount of estrogen in the body.
Description
Letrozole is a potent and highly specific nonsteroidal aromatase inhibitor. It inhibits the aromatase enzyme by competitively binding to the heme of the cytochrome P450 subunit, resulting in a reduction of estrogen biosynthesis in all tissues. It exerts its antitumor effect by depriving estrogen-dependent breast cancer cells of their growth stimulus. In postmenopausal women, estrogens are derived mainly from the action of the aromatase enzyme, which converts adrenal androgens to estrone and estradiol.
Indications
- Hormone receptor-positive early breast cancer - adjuvant therapy (postmenopausal)
- Early breast cancer - extended adjuvant therapy (after 5 years of tamoxifen)
- Hormone-dependent advanced breast cancer - first-line therapy (postmenopausal)
- Advanced breast cancer - post-antioestrogen therapy (postmenopausal)
- Localized hormone receptor-positive breast cancer - preoperative therapy
- Infertility due to anovulation
Therapeutic class
Hormonal Chemotherapy
Pharmacological class
Aromatase Inhibitor
Pharmacology
Letrozole competitively binds to the cytochrome P450 subunit of the aromatase enzyme to inhibit estrogen biosynthesis, significantly reducing plasma estrogen levels.
Mechanism of action
Reduces estrogen production from androgens by inhibiting the aromatase enzyme.
Dosage
Adult Dose (Oral):
- 2.5 mg once daily
- Adjuvant and extended adjuvant: 5 years or until tumor relapse
- Metastatic disease: until tumor progression
- Severe hepatic impairment (cirrhosis, Child-Pugh C): Reduce dose by 50% (2.5 mg every other day)
Administration
- Swallow tablet whole with water; do not chew, crush or break
- May be taken with or without food, but at a fixed time is preferable
- Take at the same time each day
Missed dose
If you miss a dose, take it as soon as possible. If it's almost time for your next dose, skip the missed dose and go back to your regular schedule. Do not double the dose.
Side effects
Common Side Effects:
- Hot flashes
- Hypercholesterolemia (high cholesterol)
- Fatigue
- Increased sweating
- Bone and joint pain (arthralgia)
- Skin rash
- Headache, dizziness
- Nausea, vomiting, dyspepsia, constipation, diarrhea
- Osteoporosis
- Edema
- Weight gain
Precautions & warnings
- Monitor liver function; dose reduction needed in severe hepatic impairment
- Monitor cholesterol and bone mineral density regularly
- Caution when driving or activities requiring concentration (may cause fatigue and dizziness)
- Contraindicated during pregnancy and lactation
- Do not use in premenopausal women
Contraindications
- Hypersensitivity to Letrozole, other aromatase inhibitors, or any ingredients
- Pregnancy and lactation
- Premenopausal women
- Severe hepatic dysfunction
Drug interactions
- Tamoxifen reduces plasma levels
- No significant clinical interactions with cimetidine and warfarin
Food interactions
Alcohol consumption with Letrozole does not cause any harmful side effects.
Use in pregnancy
Use in Pregnancy: Letrozole is highly unsafe during pregnancy. Studies on pregnant women and animals have shown significant harmful effects to the developing baby. Completely contraindicated.
Pregnancy Category: D — always consult a doctor before taking during pregnancy.
Use in lactation
Use in Lactation: Letrozole is unsafe during breastfeeding; may cause toxicity to the baby. Should not be used by nursing mothers.
Pediatric use
Not applicable for children.
Geriatric use
No dose adjustment required in elderly.
Renal / hepatic impairment
Renal Impairment: Safe in kidney disease; no dose adjustment needed (CrCl ≥10 mL/min).
Hepatic Impairment: Caution in severe hepatic impairment; dose reduction of 50% needed (cirrhosis, Child-Pugh C).
Overdose effects
No clinical experience with overdose; no specific antidote. Dialysis may be helpful.
Storage conditions
Store below 30°C, away from light and moisture; keep out of reach of children.
Chemical structure
Letrozole