Letrozol Teva Pharma (Letrozole)

Letrozole acts on hormone‑responsive breast cancer pathways, providing therapeutic benefit in several disease stages.

• Postmenopausal estrogen receptor‑positive breast cancer: reduces tumor growth and disease progression.
• Advanced or metastatic hormone‑responsive breast cancer: delays disease progression and extends survival.
• Adjuvant therapy for early‑stage hormone‑responsive breast cancer: lowers risk of recurrence after surgery.

• Letrozole selectively inhibits the aromatase enzyme, which converts androgens to estrogens in peripheral tissues. By blocking this conversion, systemic estrogen levels decline, depriving estrogen‑dependent tumor cells of growth stimulation and thereby inhibiting proliferation of hormone‑sensitive breast cancer cells.

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

Common Side Effects

• Hot flashes: transient episodes of increased skin temperature.
• Joint and muscle pain: aching or stiffness in joints and muscles.
• Fatigue: persistent feeling of tiredness.
• Nausea: mild to moderate upset stomach.
• Headache: occasional throbbing pain.
• Dizziness: sensation of light‑headedness.

Serious or Rare Side Effects

• Severe liver injury: elevated liver enzymes or hepatitis.
• Pulmonary embolism or deep‑vein thrombosis: blood clot formation in lungs or veins.
• Bone fractures: increased risk of osteoporosis‑related fractures.
• Severe allergic reaction: rash, swelling, or anaphylaxis.
• Cardiac arrhythmia: QT interval prolongation leading to irregular heartbeats.

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

• Pregnancy: contraindicated (Category X); avoid use in pregnant women.
• Breastfeeding: not recommended; discontinue if nursing.
• Liver impairment: monitor hepatic function and adjust therapy if needed.
• Bone health: assess osteoporosis risk and consider calcium/vitamin D supplementation.
• Drug interactions: review concomitant medications for potential interactions.
• Store at ambient temperature: keep below 25°C in the original packaging, protect from moisture.

Letrozole can interact with other medicines, affecting its efficacy or safety.

Major Interactions (Avoid)

• Concurrent estrogen therapy: reduces Letrozole effectiveness.
• Strong CYP2A6 inhibitors (e.g., fluvoxamine): may increase Letrozole plasma levels.
• Tamoxifen: antagonistic effect on hormonal pathways.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., rifampin): may lower Letrozole concentrations.
• Anticoagulants (e.g., warfarin): may increase bleeding risk.
• Diuretics: may alter electrolyte balance and affect bone health.