Herduo, containing the active ingredient Lapatinib, is a tyrosine kinase inhibitor used in the treatment of certain types of breast cancer. It is commonly prescribed for patients with HER2-positive breast cancer that has metastasized or advanced despite prior therapies.

Mechanism of Action

Lapatinib works by targeting the human epidermal growth factor receptor 2 (HER2) and epidermal growth factor receptor (EGFR) pathways, inhibiting their signaling. This dual blockade prevents tumor growth and proliferation.

Indications

• HER2-positive advanced or metastatic breast cancer

• In combination with capecitabine for patients previously treated with trastuzumab and chemotherapy

Onset of Action

• Lapatinib’s therapeutic effect is observed within 1 to 2 weeks of starting treatment, although full benefits may take longer.

Duration of Action

• The half-life of Lapatinib is approximately 24 hours, and steady-state concentrations are typically reached after 6 to 7 days of continuous dosing.

Dosage

• Recommended Dose: 1,250 mg orally once daily on an empty stomach (at least 1 hour before or after food).

• Combination Therapy: As directed by the healthcare provider, depending on combination drugs like capecitabine.

Side Effects

• Common: Diarrhea, nausea, rash, fatigue

• Serious: Hepatotoxicity, cardiotoxicity, severe diarrhea, and interstitial lung disease

Precautions

• Liver Function: Monitor liver enzymes regularly.

• Cardiac Function: Assess left ventricular ejection fraction (LVEF) before and during treatment.

• Pregnancy and Breastfeeding: Contraindicated due to potential harm to the fetus and infant.

• Drug Interactions: Avoid concurrent use with strong CYP3A4 inhibitors or inducers.

Contraindications

• Hypersensitivity to Lapatinib or any component of the formulation

Storage

• Store below 25°C (77°F) in a dry place away from direct sunlight.