Letrozole Tablets

Mechanism

Letrozole inhibits the aromatase enzyme, preventing conversion of androgens to estrogens. This reduces circulating estrogen levels, slowing growth of estrogen-dependent tumors and stimulating ovulation in infertility treatment.

Pharmacokinetics

• Absorption: Rapid oral absorption; bioavailability ~99%.
• Distribution: Widely distributed; plasma protein binding ~60%.
• Metabolism: Hepatic metabolism via CYP3A4 and CYP2A6.
• Elimination: Excreted in urine and feces.
• Half-life: ~2 days.

Side Effects

• Hot flashes
• Fatigue
• Arthralgia, myalgia
• Nausea
• Headache
• Bone density reduction (long-term use)

Contraindication

• Premenopausal women (unless used for infertility under supervision)
• Pregnancy and lactation
• Hypersensitivity to Letrozole

Interaction

• CYP3A4 inhibitors: May increase Letrozole levels.
• CYP inducers: Rifampicin, phenytoin may reduce efficacy.
• Estrogen-containing therapies: Antagonize Letrozole’s effect.

Warning and Precautions

• Monitor bone mineral density during long-term therapy.
• Use cautiously in patients with hepatic impairment.
• Not recommended in children or adolescents.
• Discontinue if severe allergic reaction occurs.

Dosage

As directed by the Physician.