Letrozolo Doc Generici (Letrozole)

Letrozole is used in the management of hormone‑dependent breast cancer by inhibiting estrogen production.

• Hormone receptor‑positive breast cancer (postmenopausal): reduces tumor growth by lowering estrogen levels.
• Adjuvant therapy for early‑stage breast cancer (postmenopausal): decreases risk of recurrence after surgery.
• Metastatic breast cancer (postmenopausal): controls disease progression in advanced cases.
• Neoadjuvant therapy for breast cancer (postmenopausal): shrinks tumor size before surgical removal.

• Letrozole acts as a reversible, non‑competitive inhibitor of the aromatase enzyme (CYP19A1). By binding to the enzyme’s active site, it blocks the conversion of androstenedione and testosterone to estrone and estradiol, respectively. This reduction in peripheral estrogen synthesis leads to markedly lower circulating estrogen concentrations, limiting the proliferative stimulus on estrogen‑dependent breast cancer cells.

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

Common Side Effects

• Hot flashes: transient episodes of increased skin temperature.
• Joint and muscle pain: arthralgia and myalgia.
• Fatigue: persistent tiredness.
• Nausea: mild to moderate upset stomach.
• Headache: occasional throbbing pain.
• Increased cholesterol: mild elevation of serum lipids.

Serious or Rare Side Effects

• Osteoporosis: decreased bone mineral density leading to fractures.
• Severe liver injury: marked elevation of transaminases or hepatic failure.
• Pulmonary embolism: blood clot in lung arteries.
• Deep vein thrombosis: clot formation in deep veins.
• Cardiovascular events: myocardial infarction or stroke.
• Allergic reactions: rash, angioedema, or anaphylaxis.

When prescribing Letrozole, clinicians should observe several safety considerations to minimize risks.

• Assess bone health: evaluate baseline bone mineral density and consider calcium/vitamin D supplementation.
• Monitor lipid profile: check cholesterol levels periodically during therapy.
• Evaluate liver function: perform baseline and periodic liver enzyme tests.
• Avoid use in pregnancy: Letrozole is contraindicated in pregnant women (Category X).
• Review drug interactions: check for concomitant medications that affect estrogen metabolism.
• Store at ambient temperature: keep tablets below 25 °C in the original container, protected from moisture and light.

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

Major Interactions (Avoid)

• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): may reduce letrozole plasma concentrations.
• Tamoxifen: concurrent use may diminish therapeutic effect of letrozole.

Moderate Interactions (Monitor Closely)

• Antifungal azoles (ketoconazole, itraconazole): may increase letrozole levels.
• SSRIs (e.g., fluoxetine, paroxetine): potential for altered metabolism.
• Hormone replacement therapy: may counteract estrogen suppression.
• Warfarin: possible change in anticoagulant effect, monitor INR.