Letrozole Teva (Letrozole)

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

• Hormone receptor‑positive breast cancer (postmenopausal): reduces estrogen levels to inhibit tumor growth.
• Advanced or metastatic breast cancer (postmenopausal): slows disease progression in patients with advanced disease.
• Adjuvant treatment of early‑stage hormone receptor‑positive breast cancer (postmenopausal): decreases risk of recurrence after surgery.

• Letrozole reversibly binds to the aromatase enzyme (CYP19A1) in peripheral tissues, inhibiting the conversion of androgens (androstenedione and testosterone) to estrogens (estrone and estradiol). By lowering circulating estrogen concentrations, it deprives estrogen‑dependent tumor cells of a growth stimulus, thereby exerting antineoplastic effects in hormone‑sensitive breast cancer. The inhibition is dose‑dependent and persists for several days after the last dose, allowing once‑daily oral administration.

Letrozole may be associated with a range of adverse reactions, which are generally categorized by frequency and severity.

Common Side Effects

• Hot flashes: sudden feeling of warmth, often with sweating.
• Joint and muscle pain: arthralgia or myalgia affecting mobility.
• Fatigue: persistent tiredness not relieved by rest.
• Nausea: mild to moderate upset stomach.

Serious or Rare Side Effects

• Severe liver injury: jaundice, elevated liver enzymes, hepatic failure.
• Bone fractures: increased risk of osteoporosis leading to fractures.
• Pulmonary embolism or deep vein thrombosis: sudden shortness of breath, leg swelling, chest pain.

When prescribing Letrozole, clinicians should consider several precautionary measures to ensure safe use.

• Assess bone health: evaluate risk of osteoporosis and consider calcium/vitamin D supplementation.
• Monitor liver function: perform baseline and periodic liver enzyme tests.
• Evaluate cardiovascular risk: watch for signs of thrombosis or embolism.
• Review concomitant medications: avoid drugs that strongly induce CYP3A4 which may reduce efficacy.
• Pregnancy and lactation: contraindicated in pregnancy; avoid use in women of child‑bearing potential unless effective contraception is used.
• Store at ambient temperature: keep below 25°C in the original packaging, protect from moisture and direct light.

Letrozole interacts with several medicines that may alter its efficacy or safety.

Major Interactions (Avoid)

• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): may markedly reduce letrozole plasma levels.
• Hormone replacement therapy (estrogen supplements): antagonize letrozole’s estrogen‑lowering effect.
• Anticoagulants (warfarin): increased risk of bleeding; requires close monitoring.

Moderate Interactions (Monitor Closely)

• CYP2C19 inhibitors (e.g., fluoxetine): may increase letrozole exposure, monitor for toxicity.
• Tamoxifen: combined use may affect hormonal pathways; clinical benefit unclear.
• SSRIs that affect platelet function (e.g., sertraline): may modestly increase bleeding risk.