About lapatinib
HER2 and EGFR tyrosine kinase inhibitor
Used for
- With capecitabine for advanced or metastatic HER2-positive breast cancer after prior treatment.
- With letrozole for hormone receptor-positive, HER2-positive advanced breast cancer in postmenopausal women.
Usual adult dose
1,250 mg once daily with capecitabine, or 1,500 mg once daily with letrozole; taken on an empty stomach.
Common side effects
- Diarrhea
- Rash
- Nausea and vomiting
- Fatigue
Important warnings
- Can cause serious liver injury; liver tests are monitored.
- May weaken heart pumping; heart function may need monitoring.
- Severe diarrhea can cause dehydration and requires prompt attention.
- Can prolong heart rhythm (QT interval); risk is higher with certain conditions or medicines.
Pregnancy
May harm an unborn baby. Effective contraception is recommended during treatment and for at least one week after the last dose.
Breastfeeding
Breastfeeding is not recommended during treatment and for one week after the last dose.
Interactions
- Grapefruit may increase drug levels; avoid it.
- Strong CYP3A4 inhibitors can increase levels; strong inducers can reduce effectiveness.
- Acid-reducing medicines may lower absorption.
- Can interact with medicines that prolong QT or are CYP3A4 substrates.
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.