Letrozole Pharmacenter (Letrozole)

Letrozole acts on estrogen‑dependent pathways and is employed in the management of breast cancer.

• Hormone receptor‑positive breast cancer (postmenopausal): Reduces estrogen levels to inhibit tumor proliferation.
• Adjuvant therapy for early‑stage breast cancer: Decreases risk of disease recurrence after surgery.
• Metastatic breast cancer (postmenopausal): Controls disease progression by limiting estrogen‑driven growth.

• Letrozole selectively inhibits the aromatase enzyme, which converts adrenal androgens into estrogens in peripheral tissues. By blocking this conversion, systemic estrogen concentrations fall, depriving estrogen‑dependent tumor cells of a key growth stimulus and thereby slowing or halting cancer progression.

Letrozole may cause a range of adverse reactions that vary in frequency and severity.

Common Side Effects

• Hot flashes: Sudden feeling of warmth, often with sweating.
• Joint and muscle pain: Discomfort in joints, muscles, or the back.
• Fatigue: Persistent tiredness not relieved by rest.
• Nausea: Mild to moderate upset stomach.
• Headache: Pressure or throbbing pain in the head.
• Dizziness: Light‑headed sensation, especially when standing.

Serious or Rare Side Effects

• Severe liver injury: Jaundice, dark urine, or elevated liver enzymes.
• Bone fractures: Increased risk due to reduced bone mineral density.
• Pulmonary embolism: Sudden shortness of breath, chest pain, or coughing up blood.
• Allergic reactions: Rash, itching, swelling, or difficulty breathing.
• Severe hypertension: Markedly high blood pressure requiring urgent care.
• Cardiovascular events: Heart attack or stroke in susceptible patients.

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

• Bone health monitoring: Assess baseline bone mineral density and consider calcium/vitamin D supplementation.
• Liver function assessment: Perform baseline liver enzyme tests and repeat as clinically indicated.
• Cardiovascular risk evaluation: Review history of hypertension, thromboembolic disease, or cardiac events.
• Pregnancy contraindication: Do not use in pregnant or nursing women; ensure effective contraception.
• Premenopausal status: Avoid in women with active ovarian function unless ovarian suppression is confirmed.
• Drug interaction vigilance: Review concomitant medications that may alter letrozole metabolism.
• Store at ambient temperature below 25°C: Keep in the original packaging, protect from moisture and light.

Letrozole may interact with other medicines, influencing its effectiveness or safety.

Major Interactions (Avoid)

• Tamoxifen: Antagonistic effect reducing therapeutic benefit.
• Strong CYP2C8 inhibitors (e.g., gemfibrozil): May increase letrozole plasma levels.
• Strong CYP2C9 inhibitors (e.g., fluconazole): Can elevate drug exposure and toxicity.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., rifampin, carbamazepine): May lower letrozole concentrations, reducing efficacy.
• CYP2A6 inhibitors (e.g., methoxsalen): May modestly raise letrozole levels.
• Warfarin: Potentially increased INR; monitor coagulation parameters.