Letrozol Edigen (Letrozole)

Letrozole is an aromatase inhibitor used in the management of hormone‑dependent breast cancer.

• Metastatic breast cancer: reduces tumor progression in postmenopausal women with hormone‑receptor‑positive disease.
• Early‑stage adjuvant therapy: lowers risk of recurrence after surgery in hormone‑receptor‑positive breast cancer.
• Extended adjuvant therapy: provides continued estrogen suppression following 5 years of tamoxifen in postmenopausal patients.

• Letrozole reversibly binds to the aromatase enzyme (CYP19A1) in peripheral tissues, inhibiting the conversion of androstenedione and testosterone to estrone and estradiol. This reduction in circulating estrogen deprives estrogen‑dependent tumor cells of growth stimulation, thereby slowing or halting the progression of hormone‑receptor‑positive breast cancer.

Letrozole may cause a range of adverse reactions, most of which are mild to moderate.

Common Side Effects

• Hot flashes: sudden feeling of warmth, often with sweating.
• Joint and muscle pain: aching in knees, hips, or shoulders.
• Fatigue: persistent tiredness not relieved by rest.
• Nausea: mild stomach upset or queasiness.
• Headache: pressure or throbbing pain in the head.
• Increased sweating: excessive perspiration unrelated to activity.

Serious or Rare Side Effects

• Severe liver injury: jaundice, dark urine, or abdominal pain.
• Bone fracture: increased risk of osteoporosis‑related breaks.
• Pulmonary embolism: sudden shortness of breath, chest pain.
• Deep vein thrombosis: swelling, pain, or redness in a limb.
• Allergic reactions: rash, itching, swelling of face or throat.
• Elevated cholesterol: significant rise in blood lipid levels.

Before initiating Letrozol Edigen, clinicians should consider several safety measures.

• Bone health monitoring: assess baseline bone mineral density and consider calcium/vitamin D supplementation.
• Liver function assessment: obtain baseline hepatic enzymes and repeat periodically.
• Cardiovascular risk evaluation: review history of thromboembolic events or hyperlipidaemia.
• Pregnancy and lactation avoidance: ensure effective contraception in women of child‑bearing potential.
• Pre‑menopausal status: avoid use in women who have not reached menopause.
• Store at ambient temperature: keep below 25 °C in the original packaging, protect from moisture and direct sunlight.

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

Major Interactions (Avoid)

• Concomitant estrogen therapy: may counteract aromatase inhibition and reduce anticancer effect.
• Tamoxifen: antagonistic action can diminish therapeutic benefit.
• Strong CYP2A6 inhibitors (e.g., methoxsalen): can increase letrozole plasma concentrations.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., rifampin, carbamazepine): may lower letrozole levels, reducing effectiveness.
• Warfarin: letrozole may enhance anticoagulant effect, requiring INR monitoring.
• Statins metabolised by CYP3A4: increased risk of myopathy; monitor muscle symptoms.