Lapatinib Teva (Lapatinib)

Lapatinib is a targeted therapy that acts on HER2‑driven malignancies.

• HER2‑positive metastatic breast cancer: used in combination with other agents to delay disease progression.
• HER2‑positive locally advanced breast cancer: administered when disease is not amenable to curative surgery.
• HER2‑positive gastric or gastro‑oesophageal adenocarcinoma: employed as part of combination regimens to improve clinical outcomes.

• Lapatinib binds to the intracellular tyrosine kinase domains of epidermal growth factor receptor (EGFR/HER1) and HER2, preventing autophosphorylation and downstream signaling through the MAPK and PI3K/AKT pathways. This inhibition reduces cellular proliferation, induces apoptosis, and limits tumor angiogenesis, thereby slowing the growth of HER2‑driven cancers.

Lapatinib may cause a range of adverse reactions that vary in frequency and severity.

Common Side Effects

• Diarrhea: watery stools occurring in many patients.
• Rash: skin eruptions, often on the trunk or extremities.
• Nausea: mild to moderate feeling of stomach upset.
• Fatigue: generalized tiredness affecting daily activities.
• Stomatitis: inflammation or ulceration of the mouth lining.
• Elevated liver enzymes: increased ALT/AST on laboratory testing.

Serious or Rare Side Effects

• Cardiac dysfunction: reduced left ventricular ejection fraction.
• Severe skin reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Hepatotoxicity: clinically significant liver injury.
• Interstitial lung disease: non‑infectious pulmonary inflammation.

Patients receiving Lapatinib should be monitored for specific safety considerations.

• Cardiac monitoring: assess left ventricular function before and during therapy.
• Liver function: perform baseline and periodic ALT/AST tests.
• Skin assessment: watch for severe rash or mucosal involvement.
• Drug interactions: review concomitant medications that affect CYP3A4.
• Pregnancy and lactation: avoid use unless benefits outweigh potential risks.
• Store at ambient temperature: keep below 25 °C, retain in original packaging, protect from moisture and direct sunlight.

Lapatinib interacts with several drug classes that may alter its efficacy or safety.

Major Interactions (Avoid)

• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): may markedly reduce plasma levels.
• Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin): can increase exposure and toxicity.
• Antacids containing aluminum or magnesium: may decrease absorption if taken simultaneously.

Moderate Interactions (Monitor Closely)

• Warfarin: potential alteration of anticoagulant effect, monitor INR.
• Digoxin: possible increase in serum concentrations, observe for toxicity.
• Other HER‑targeted agents: additive cardiac risk, evaluate cardiac function regularly.