Letrozol Abz (Letrozole)

Letrozol Abz acts on estrogen‑dependent breast cancer pathways and is indicated for several clinical scenarios.

• Hormone receptor‑positive breast cancer (postmenopausal): Reduces estrogen production to inhibit tumor growth.
• Adjuvant treatment of early‑stage breast cancer (postmenopausal): Lowers the risk of disease recurrence after surgery.
• Metastatic breast cancer (postmenopausal): Delays disease progression and extends survival.

• Letrozole reversibly binds to the aromatase enzyme, a non‑steroidal inhibitor that blocks the conversion of androgens to estrogens. By decreasing systemic estrogen levels, it deprives estrogen‑dependent tumor cells of a growth stimulus, thereby slowing or halting cancer progression in postmenopausal patients.

Adverse reactions may occur with letrozole therapy and are categorized by frequency.

Common Side Effects

• Hot flashes: Sudden feeling of warmth, often with sweating.
• Arthralgia: Joint pain or stiffness.
• Fatigue: Persistent tiredness unrelated to activity.
• Nausea: Mild to moderate upset stomach.
• Headache: Tension‑type or migraine‑like pain.
• Insomnia: Difficulty initiating or maintaining sleep.

Serious or Rare Side Effects

• Severe liver injury: Jaundice, elevated transaminases.
• Bone fracture: Increased risk due to reduced bone mineral density.
• Deep vein thrombosis or pulmonary embolism: Swelling, pain, or shortness of breath.
• Anaphylaxis: Rapid onset of rash, airway swelling, or hypotension.
• QT interval prolongation: Potential cardiac arrhythmias.
• Severe allergic reaction: Skin rash, itching, or swelling.

Patients should be monitored for specific safety considerations before and during letrozole therapy.

• Bone health monitoring: Assess bone mineral density periodically to detect osteoporosis.
• Liver function testing: Perform baseline and periodic liver enzyme assessments.
• Cardiovascular risk evaluation: Review history of thromboembolic events.
• Hot flash management: Counsel patients on lifestyle measures and possible supportive therapy.
• Pregnancy avoidance: Ensure effective contraception; letrozole is contraindicated in pregnancy.
• Store at room temperature: Keep in the original container, protect from moisture and direct sunlight.

Letrozole may interact with other medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Estrogen‑containing hormone therapy: Counteracts letrozole’s estrogen‑lowering effect.
• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): May markedly reduce plasma concentrations.
• Potent CYP2C19 inhibitors (e.g., fluconazole): Can increase exposure and risk of toxicity.

Moderate Interactions (Monitor Closely)

• Warfarin: May enhance anticoagulant effect; monitor INR closely.
• Antacids containing aluminum or magnesium: May affect absorption; separate administration by at least 2 hours.
• CYP2D6 substrates (e.g., tamoxifen): Potential for altered metabolism; clinical significance uncertain.