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HER2/EGFR tyrosine-kinase inhibitor

Lapatinib (Specialist drug)

Brand names: Tyverb

Lapatinib is an oral dual tyrosine kinase inhibitor of HER2 and EGFR used as a specialist treatment for HER2-positive breast cancer, usually in combination with chemotherapy or endocrine therapy. It is taken once daily under oncology supervision.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It reversibly inhibits the intracellular tyrosine kinase domains of HER2 (ERBB2) and EGFR (ERBB1), blocking downstream growth and survival signalling in HER2-positive tumour cells.

Prescribing in practice

  • It can reduce left ventricular ejection fraction and cause QT prolongation, so cardiac function and electrolytes should be assessed and monitored.
  • Hepatotoxicity occurs and liver function must be monitored; severe diarrhoea is also common and needs early management.
  • It is metabolised by CYP3A4, so avoid strong inducers and inhibitors and take consistently in relation to food as directed.

Monitoring

Monitor left ventricular ejection fraction, liver function tests and for diarrhoea during treatment.

Counselling the patient

  • Report breathlessness, ankle swelling or palpitations, which may indicate a heart problem.
  • Manage diarrhoea early and contact the team if it is severe or persistent.
  • Avoid grapefruit and tell the team about all other medicines, as interactions are important.

Evidence & guidelines

Lapatinib combined with capecitabine improved outcomes in HER2-positive advanced breast cancer after trastuzumab in a pivotal trial.

Reference: NICE TA257; SmPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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