lapatinib ditosylate monohydrate at a glance
Medicine class
HER2 and EGFR tyrosine kinase inhibitor
Usual role
Combination treatment for selected HER2-overexpressing advanced or metastatic breast cancers
Administration
Swallow whole with water, consistently at least one hour before or after food
Food and drink
Food substantially changes absorption; avoid grapefruit juice
What is lapatinib ditosylate monohydrate used for?
UK-licensed uses are for adults whose breast cancer overexpresses HER2.
With capecitabine for advanced or metastatic disease that has progressed after specified previous treatments, including trastuzumab in the metastatic setting.
With trastuzumab for hormone receptor-negative metastatic disease that has progressed after previous trastuzumab with chemotherapy.
With an aromatase inhibitor for postmenopausal women with hormone receptor-positive metastatic disease who are not currently intended for chemotherapy.
How does lapatinib ditosylate monohydrate work?
It inhibits the internal tyrosine kinase regions of HER2 and EGFR, reducing growth signals used by some cancer cells. Combining it with another treatment attacks the cancer through complementary mechanisms.
How to take lapatinib ditosylate monohydrate
Follow the oncology team's instructions and the information for every accompanying anticancer treatment.
Swallow the tablets whole with water.
Take them at least one hour before or at least one hour after food.
Keep their timing in relation to food consistent.
Avoid grapefruit juice.
lapatinib ditosylate monohydrate side effects
Common or expected effects
- Diarrhoea, nausea or vomiting
- Rash, dry skin or itching
- Reduced appetite
- Tiredness or weakness
- Indigestion, abdominal pain, constipation or mouth inflammation
- Hand-and-foot skin reaction, particularly with capecitabine
- Headache, cough or breathlessness
- Hair thinning, nail problems or skin fissures
Get urgent medical advice
- Severe diarrhoea causing dehydration, kidney problems or electrolyte disturbance
- Reduced heart-pumping function or abnormal heart rhythm
- Liver injury
- Interstitial lung disease or pneumonitis
- Severe blistering or peeling skin reactions
- Severe allergic reaction
lapatinib ditosylate monohydrate in pregnancy
Human pregnancy data are inadequate and animal studies found reproductive toxicity. It should not be used during pregnancy unless clearly necessary. Discuss pregnancy or plans to conceive with the specialist team; effective contraception is advised during treatment and for at least 5 days after the last dose.
lapatinib ditosylate monohydrate while breastfeeding
It is unknown whether lapatinib enters human milk, and safe use while breastfeeding has not been established. Breastfeeding must stop during treatment and for at least 5 days after the last dose; discuss feeding plans with the specialist team.
lapatinib ditosylate monohydrate interactions
A full medicines review is essential, including non-prescription and herbal products.
Strong CYP3A4 inhibitors, including azole antifungals and some antivirals
They can substantially increase lapatinib exposure and toxicity, so combined use should be avoided.
CYP3A4 inducers, including rifampicin, carbamazepine, phenytoin and St John's wort
They can lower lapatinib exposure and potentially reduce its effect, so combined use should be avoided.
Proton-pump inhibitors and other medicines that raise stomach pH
They may reduce lapatinib solubility and absorption and should generally be avoided.
Common questions about lapatinib ditosylate monohydrate
Answers are fully visible for fast scanning and source review.
Is lapatinib ditosylate monohydrate chemotherapy or targeted therapy?
It is targeted therapy: a small-molecule tyrosine kinase inhibitor of HER2 and EGFR. It may be prescribed with chemotherapy or another targeted or hormonal treatment.
Why must it be taken away from food?
Food can markedly and variably increase absorption. Consistent timing before or after food helps limit variation in exposure.
What tests are needed?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.