Letrozol Labormed (Letrozole)

Letrozole belongs to the aromatase inhibitor class and is used in hormone‑dependent breast cancer management.

• Postmenopausal estrogen receptor‑positive breast cancer: reduces recurrence risk and slows disease progression.
• Adjuvant therapy for hormone‑receptor positive breast cancer: improves disease‑free survival after surgery.
• Metastatic breast cancer in postmenopausal women: helps control tumor growth and extends survival.

• Letrozole selectively inhibits the aromatase enzyme, which converts adrenal and peripheral androgens into estrogens. By blocking this conversion, systemic estrogen concentrations fall, depriving estrogen‑dependent tumor cells of a growth stimulus and thereby limiting proliferation of hormone‑sensitive breast cancer.

Letrozole may cause a range of adverse reactions, from mild to severe.

Common Side Effects

• Hot flashes: sudden feeling of warmth, often with sweating.
• Arthralgia: joint pain or stiffness.
• Fatigue: persistent tiredness not relieved by rest.
• Nausea: mild to moderate upset stomach.
• Headache: pressure or throbbing pain.
• Dizziness: light‑headed sensation.

Serious or Rare Side Effects

• Severe liver dysfunction: jaundice, elevated enzymes.
• Bone fracture: increased risk of osteoporosis‑related breaks.
• Pulmonary embolism: sudden shortness of breath, chest pain.
• Myocardial infarction: heart attack symptoms.
• Anaphylaxis: severe allergic reaction with swelling and airway compromise.
• Elevated cholesterol: significant rise in blood lipid levels.

Before initiating Letrozole therapy, several safety considerations should be addressed.

• Bone health monitoring: assess bone mineral density regularly.
• Liver function testing: check hepatic enzymes before and during treatment.
• Cardiovascular risk assessment: evaluate history of heart disease or clotting disorders.
• Concomitant hormone therapy review: avoid estrogen‑containing products.
• Use in premenopausal women: contraindicated unless ovarian suppression is confirmed.
• Store at ambient temperature: keep in the original container, protect from moisture and direct sunlight.

Letrozole can interact with other medicines, requiring attention to avoid reduced efficacy or increased toxicity.

Major Interactions (Avoid)

• Estrogen replacement therapy: negates aromatase inhibition.
• Tamoxifen: antagonistic effects on estrogen pathways.
• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): markedly lower Letrozole plasma levels.
• Warfarin: may increase anticoagulant effect, requiring close INR monitoring.

Moderate Interactions (Monitor Closely)

• CYP2A6 inhibitors (e.g., fluvoxamine): may raise Letrozole concentrations.
• Statins: potential additive effect on liver enzymes.
• Glucocorticoids: may enhance bone loss risk.
• Antidepressants (SSRIs): possible increase in hot‑flash severity.
• Antifungal azoles: may modestly increase Letrozole exposure.