About lapatinib tosilate
Tyrosine kinase inhibitor
Used for
- HER2-positive advanced or metastatic breast cancer with capecitabine after prior treatment.
- Hormone receptor-positive, HER2-positive metastatic breast cancer with letrozole.
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 prolong QT interval or weaken heart pumping.
- Severe diarrhea can cause dehydration and kidney problems.
- Take at the same time daily; avoid grapefruit and high-fat meals.
Pregnancy
Can harm an unborn baby. Effective contraception is recommended during treatment and for one week after the last dose.
Breastfeeding
Breastfeeding is not recommended during treatment and for one week after the last dose.
Interactions
- Strong CYP3A4 inhibitors can raise lapatinib levels; inducers can lower them.
- May interact with medicines that prolong QT interval.
- Can interact with acid-reducing medicines and drugs transported by P-glycoprotein or BCRP.
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 It may be incomplete or out of date.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.