Letrolan (Letrozole)

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

• Postmenopausal estrogen receptor‑positive breast cancer: reduces tumor progression and disease recurrence.
• Adjuvant therapy for early‑stage hormone‑receptor‑positive breast cancer: lowers risk of cancer returning after surgery.
• Metastatic hormone‑receptor‑positive breast cancer: improves overall survival and delays disease spread.

• Letrozole reversibly binds to the aromatase enzyme, inhibiting its activity. By blocking the conversion of androgens to estrogens, systemic estrogen levels fall, depriving estrogen‑dependent tumor cells of a growth stimulus and thereby limiting cancer proliferation.

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

Common Side Effects

• Hot flashes: sudden feeling of warmth and sweating.
• Joint and muscle pain: aching in limbs and joints.
• Fatigue: persistent tiredness.
• Nausea: upset stomach and possible vomiting.
• Headache: mild to moderate cranial pain.
• Dizziness: sensation of light‑headedness.

Serious or Rare Side Effects

• Severe liver injury: jaundice, elevated enzymes.
• Bone fracture: increased risk due to bone density loss.
• Pulmonary embolism: sudden shortness of breath, chest pain.
• Allergic reaction: rash, swelling, anaphylaxis.
• QT interval prolongation: cardiac rhythm disturbance.
• Hypercholesterolemia: significant rise in cholesterol levels.

Before initiating Letrozole therapy, several safety considerations are essential.

• Pregnancy contraindication: avoid use in pregnant women; teratogenic risk.
• Breastfeeding prohibition: do not use while nursing; drug passes into milk.
• Bone health monitoring: assess bone mineral density periodically.
• Liver function assessment: check hepatic enzymes before and during treatment.
• Lipid profile surveillance: monitor cholesterol levels regularly.
• Avoid use in premenopausal women: efficacy not established.
• Store at ambient temperature: keep in original packaging, protect from moisture.

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

Major Interactions (Avoid)

• Tamoxifen: antagonistic effect reduces therapeutic benefit.
• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): markedly lower letrozole plasma levels.
• Strong CYP2A6 inhibitors (e.g., methoxsalen): increase letrozole exposure and toxicity.
• Estrogen replacement therapy: diminishes aromatase inhibition.

Moderate Interactions (Monitor Closely)

• Warfarin: possible increase in INR, requiring closer coagulation monitoring.
• Statins (especially simvastatin): heightened risk of myopathy.
• SSRIs (e.g., fluoxetine): may modestly affect QT interval.
• Anticonvulsants (e.g., phenytoin): may alter hormone metabolism.
• Proton pump inhibitors: occasional effect on absorption, monitor clinical response.