Letrozol Pensa Pharma (Letrozole)

Letrozole is indicated for hormone‑dependent breast cancer and works by targeting estrogen synthesis.

• Postmenopausal estrogen receptor‑positive breast cancer: reduces tumor progression by lowering circulating estrogen levels.
• Adjuvant therapy for early‑stage hormone‑receptor positive breast cancer: decreases risk of recurrence after surgery.
• Metastatic hormone‑receptor positive breast cancer in postmenopausal women: helps control disease spread by suppressing estrogen‑driven growth.

• Letrozole selectively and non‑competitively inhibits the aromatase enzyme, a cytochrome P450 isoform that converts androstenedione and testosterone into estrone and estradiol in peripheral tissues. By blocking this conversion, systemic estrogen concentrations fall, depriving estrogen‑dependent tumor cells of a growth stimulus.

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

Common Side Effects

• Hot flashes: sudden feeling of warmth and sweating.
• Arthralgia: joint pain or stiffness.
• Fatigue: persistent tiredness.
• Nausea: mild to moderate upset stomach.

Serious or Rare Side Effects

• Osteoporosis: decreased bone mineral density leading to fractures.
• Cardiovascular events: increased risk of thromboembolic disease.
• Severe liver injury: marked elevation of hepatic enzymes or hepatitis.

When prescribing Letrozole, clinicians should consider several safety measures and monitoring requirements.

• Bone health monitoring: assess bone mineral density regularly and consider calcium/vitamin D supplementation.
• Cardiovascular assessment: evaluate risk factors for thromboembolism before initiation.
• Liver function testing: perform baseline and periodic liver enzyme tests.
• Drug interactions: review concomitant medications for potential CYP2A6 inhibitors or inducers.
• Store at ambient temperature: keep tablets below 25 °C in the original container, protect from moisture and light.

Letrozole can interact with other medicines that affect its metabolism or hormonal pathways.

Major Interactions (Avoid)

• Strong CYP2A6 inhibitors (e.g., fluvoxamine): may increase Letrozole plasma levels, raising toxicity risk.
• Estrogen‑containing hormonal therapies (e.g., hormone replacement therapy): counteract Letrozole’s estrogen‑lowering effect.

Moderate Interactions (Monitor Closely)

• CYP2A6 inducers (e.g., rifampicin): may reduce Letrozole exposure, diminishing efficacy.
• Anticoagulants (e.g., warfarin): Letrozole may enhance anticoagulant effect, requiring INR monitoring.
• Tamoxifen: concurrent use may increase risk of adverse events; clinical judgment required.