Lapatinibinfo-icon (Tykerbinfo-icon) is targeted therapyinfo-icon in the dual tyrosine kinase inhibitor class. It is used with the chemotherapyinfo-icon pill capecitabineinfo-icon (Xelodainfo-icon) or the aromatase inhibitorinfo-icon letrozoleinfo-icon (Femarainfo-icon) to treat HER2-positive metastatic breast cancer after treatment with other medicines.

How Lapatinib Works

Lapatinibinfo-icon blocks the action of the HER2 proteininfo-icon from the inside the cellinfo-icon. You may be familiar with trastuzumab (Herceptin), a targeted therapyinfo-icon that also blocks the HER2 protein. While trastuzumabinfo-icon works on the outside of the cell, lapatinib works on the inside. This deprives the cancer cells of what they need to grow.

Because of the differences in how they attack cancer cells, lapatinib works in some HER2-positive cancers that stop responding to trastuzumab.

How Lapatinib Is Given

Lapatinibinfo-icon is available as pill. The standard doseinfo-icon is five tablets a day. If the treatment causes difficult side effects, your doctor may be able to reduce the number of pills you take each day.

You should take lapatinib at least one hour before or one hour after eating.

Side Effects and Things to Remember

Eating grapefruit or products made with grapefruit may impact how well your body breaks down lapatinibinfo-icon, so avoid both while you are taking this medicineinfo-icon. Grapefruit contains a natural chemical, normally safe, that interacts with some medicines.

Common side effects from lapatinib may include

If you are also taking capecitabine or letrozoleinfo-icon, you could have side effects related to those medicines as well.

Before starting lapatinib, talk to your doctor about any heart and liver problems you have. Let your providers know about any medicines you are taking, including vitamins, herbal supplements and over-the-counterinfo-icon medicines.

Tell your doctor if you have side effects. If they are interfering with your everyday life, your doctor may be able to change your doseinfo-icon or switch you to another medicine. Seek medical help right away if you feel any chest pain. You should not become pregnant while you are taking lapatinib.

Your doctor, pharmacistinfo-icon or nurseinfo-icon can help you manage your side effects. You can also go to our section on Side Effects for more information.

March 19, 2018
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