Letrozole Accord Healthcare (Letrozole)

Letrozole is an aromatase inhibitor used in hormone‑dependent breast cancer therapy. It is indicated for several disease stages:

• Breast cancer (postmenopausal women): Reduces estrogen‑driven tumor growth and improves disease‑free survival.
• Early‑stage hormone receptor‑positive breast cancer (adjuvant setting): Decreases risk of cancer recurrence after surgery.
• Metastatic hormone‑sensitive breast cancer: Helps control disease progression and prolongs overall survival.

• Letrozole selectively binds to the aromatase enzyme, blocking its activity and preventing the conversion of adrenal and peripheral androgens into estrogens. This results in markedly reduced circulating estrogen concentrations, which limits the proliferative stimulus on estrogen‑dependent breast cancer cells and impedes tumor growth.

Letrozole may cause a range of adverse reactions. Patients should be aware of both frequent and less common events.

Common Side Effects

• Hot flashes: Sudden feeling of warmth and sweating.
• Joint and muscle pain: Arthralgia and myalgia affecting daily activities.
• Fatigue: Persistent tiredness not relieved by rest.
• Nausea: Mild to moderate upset stomach.
• Headache: Pressure or throbbing pain in the head.
• Insomnia: Difficulty falling or staying asleep.

Serious or Rare Side Effects

• Severe liver injury: Jaundice, dark urine, or elevated liver enzymes.
• Bone fractures: Increased risk due to reduced bone mineral density.
• Deep vein thrombosis or pulmonary embolism: Swelling, pain, or shortness of breath.
• Allergic reactions: Rash, itching, swelling, or anaphylaxis.
• Severe skin reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Cardiovascular events: Unexplained chest pain or arrhythmias.

Before initiating Letrozole therapy, clinicians should consider several safety measures.

• Bone health monitoring: Assess baseline bone mineral density and consider calcium/vitamin D supplementation.
• Liver function assessment: Perform baseline liver enzyme tests and monitor periodically.
• Cardiovascular risk evaluation: Review history of thrombosis or heart disease.
• Pregnancy avoidance: Ensure effective contraception; drug is contraindicated in pregnancy.
• Renal impairment caution: Adjust therapy if severe renal dysfunction is present.
• Store at room temperature: Keep in the original container, protect from moisture and direct sunlight.

Letrozole can interact with other medicines, affecting its efficacy or safety.

Major Interactions (Avoid)

• Estrogen replacement therapy: Opposes Letrozole’s estrogen‑lowering effect.
• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): May markedly reduce Letrozole plasma levels.
• Concurrent aromatase inhibitors: Additive toxicity without therapeutic benefit.

Moderate Interactions (Monitor Closely)

• Warfarin: Potential increase in INR; monitor coagulation parameters.
• Statins: May raise risk of myopathy when combined.
• Glucocorticoids: Heightened risk of osteoporosis; monitor bone health.