Letrozol Stada (Letrozole)

• Letrozole acts on estrogen‑dependent pathways in breast cancer and is indicated for the following conditions:
• Hormone receptor‑positive early‑stage breast cancer (postmenopausal): Improves disease‑free survival when given as adjuvant therapy after surgery.
• Metastatic hormone receptor‑positive breast cancer (postmenopausal): Provides hormonal control to delay disease progression.
• Adjuvant treatment of early‑stage breast cancer (postmenopausal): Reduces risk of recurrence when combined with other therapies.
• Locally advanced breast cancer (postmenopausal): Used to shrink tumors before surgery.

• Letrozole selectively and reversibly binds to the aromatase enzyme, a cytochrome P450 isoform responsible for converting androstenedione and testosterone into estrone and estradiol. By inhibiting this non‑steroidal aromatase activity, systemic estrogen levels fall markedly, depriving estrogen‑dependent tumor cells of a growth stimulus. The inhibition is dose‑dependent and persists for several days after the last dose, allowing sustained estrogen suppression throughout the treatment cycle.

Letrozole may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Hot flashes: Sudden feeling of warmth, often with sweating.
• Joint and muscle pain: Arthralgia or myalgia affecting daily activities.
• Fatigue: Persistent tiredness not relieved by rest.
• Nausea: Mild to moderate upset stomach.

Serious or Rare Side Effects

• Severe liver injury: Elevated transaminases or hepatic failure.
• Bone fracture: Increased risk of osteoporosis‑related fractures.
• Pulmonary embolism: Sudden shortness of breath and chest pain.
• Anaphylaxis: Life‑threatening allergic reaction with rash, swelling, and airway compromise.

• Before initiating Letrozole therapy, clinicians should evaluate several safety considerations.
• Bone health assessment: Monitor bone mineral density and consider calcium/vitamin D supplementation.
• Liver function monitoring: Check baseline hepatic enzymes and repeat periodically.
• Cardiovascular risk review: Assess history of thromboembolic events or hyperlipidaemia.
• Menopausal status verification: Avoid use in premenopausal women unless ovarian suppression is confirmed.
• Concomitant medication review: Evaluate for drugs that may alter letrozole metabolism.
• Store at ambient temperature: Keep tablets in the original container, protect from moisture and light.

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

Major Interactions (Avoid)

• Tamoxifen: Antagonistic effect reduces therapeutic benefit of letrozole.
• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): Significantly lower plasma concentrations, diminishing efficacy.
• Estrogen‑containing hormone therapy: Counteracts estrogen suppression.

Moderate Interactions (Monitor Closely)

• Moderate CYP3A4 inhibitors (e.g., ketoconazole, erythromycin): May increase letrozole levels, requiring observation.
• Warfarin: Potential alteration of anticoagulant effect; monitor INR.
• Cholesterol‑lowering agents (statins): Possible increased risk of muscle toxicity; assess symptoms.