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Lapatinib Dosage

Medically reviewed by Last updated on Mar 18, 2024.

Applies to the following strengths: 250 mg

Usual Adult Dose for Breast Cancer

HER2-Positive Metastatic Breast Cancer (in combination with capecitabine):
1250 mg orally once a day on Days 1 to 21 continuously in repeating 21-day cycles in combination with capecitabine 2000 mg/m2/day (administered orally in 2 doses approximately 12 hours apart) on Days 1 to 14 in a repeating 21-day cycle

Hormone Receptor-Positive, HER2-Positive Metastatic Breast Cancer (in combination with letrozole):
1500 mg orally once a day continuously in combination with letrozole 2.5 mg orally once a day


is not recommended [see Clinical Pharmacology (12.3)]. Capecitabine should be taken with food or within 30 minutes after food. If a day's dose is missed, the patient should not double the dose the next day. Treatment should be continued until disease progression or unacceptable toxicity occurs.


Renal Dose Adjustments

Data not available regarding dosage adjustments; however, the pharmacokinetics of this drug are unlikely to be affected given that less than 2% of an administered dose is eliminated by the kidneys.

Liver Dose Adjustments

Preexisting severe hepatic impairment (Child-Pugh C):

Severe hepatic impairment that develops during therapy (Child-Pugh C):

Dose Adjustments

CONCOMITANT USE WITH STRONG CYP450 3A4 INHIBITORS AND/OR STRONG CYP450 3A4 INDUCERS: Avoid concomitant use if possible. Dose adjustment recommendations are based on pharmacokinetic studies; there are no clinical data available.
CONCOMITANT USE WITH STRONG CYP450 3A4 INHIBITOR: Reduce dose to 500 mg/day; allow washout period of approximately 1 week before upward adjustment of this drug to the usual recommended dose if inhibitor discontinued.
CONCOMITANT USE WITH STRONG CYP450 3A4 INDUCER: Gradually up-titrate dose based on tolerability; decrease dose back to the usual recommended dose if inducer discontinued.

GRADE 2 or GREATER DECREASED LEFT VENTRICULAR EJECTION FRACTION (LVEF) OR LVEF THAT DROPS BELOW INSTITUTION'S LOWER LIMIT OF NORMAL: Discontinue treatment; may restart at reduced dose after a minimum of 2 weeks if LVEF recovers to normal and patient is asymptomatic.
Reduced Doses:

GRADE 3 OR GRADE 1 or 2 DIARRHEA WITH COMPLICATING FEATURES (moderate to severe abdominal cramping, Grade 2 or greater nausea or vomiting, decreased performance status, fever, sepsis, neutropenia, frank bleeding, or dehydration): May reintroduce at lower dose when diarrhea resolves to Grade 1 or less.
Reduced Doses:
GRADE 4 DIARRHEA: Permanently discontinue treatment.

OTHER TOXICITIES, GRADE 2 or GREATER: May consider discontinuation or interruption of dosing; may restart at the usual recommended dose when toxicity improves to Grade 1 or less.




Safety and efficacy have not been established in patients younger than 18 years.

Consult WARNINGS section for additional precautions.


Data not available; however, hemodialysis would not be expected to be an effective method to enhance drug elimination because this drug is not significantly renally excreted (less than 2%) and is highly bound to plasma proteins (more than 99%)

Other Comments

Administration Advice:

Storage Requirements:



Patient Advice:

Frequently asked questions

Further information

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