What is the most important information I should know about lapatinib?
Do not use lapatinib if you are pregnant. It could harm the unborn baby.
Lapatinib can cause severe or fatal liver problems.
Call your doctor at once if you have signs of liver problems: upper stomach pain, itching, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).
What is lapatinib?
Lapatinib is a cancer medicine that interferes with the growth and spread of cancer cells in the body.
Lapatinib is used to treat a certain type of hormone-related breast cancer that has progressed or spread after treatment with other cancer medicines.
In postmenopausal women, lapatinib is given in combination with a hormonal medicine called letrozole (Femara). In others, lapatinib is given together with a cancer medicine called capecitabine (Xeloda).
Lapatinib may also be used for purposes not listed in this medication guide.
What should I discuss with my healthcare provider before taking lapatinib?
You should not use lapatinib if you are allergic to it.
To make sure lapatinib is safe for you, tell your doctor if you have:
- heart disease;
- liver disease (lapatinib can cause severe or fatal liver problems);
- an electrolyte imbalance (such as low levels of potassium or magnesium in your blood); or
- a personal or family history of long QT syndrome.
Do not use lapatinib if you are pregnant. It could harm the unborn baby or cause birth defects. Use effective birth control to prevent pregnancy while you are using this medicine. Tell your doctor right away if you become pregnant.
It is not known whether lapatinib passes into breast milk or if it could harm a nursing baby. You should not breast-feed while you are taking this medicine.
How should I take lapatinib?
Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.
Read all patient information, medication guides, and instruction sheets provided to you. Ask your doctor or pharmacist if you have any questions. Be sure to also read the medication guides for capecitabine or letrozole.
When used with letrozole, the usual dose of lapatinib is 6 tablets taken once daily every day. Letrozole is also taken every day.
When used with capecitabine, lapatinib is usually taken in a 21-day cycle. You will take lapatinib in a dose of 5 tablets once daily for all 21 days in a row. You will take capecitabine twice daily for only the first 14 days of the cycle. This 21-day cycle is then repeated.
Your doctor will tell you how much capecitabine or letrozole to take. Follow your doctor's dosing instructions very carefully.
Take lapatinib on an empty stomach, at least 1 hour before or 1 hour after a meal.
You may swallow each lapatinib tablet one at a time, but take the entire dose (all 5 or 6 tablets) at the same time each day.
Capecitabine must be taken with food or within 30 minutes of eating.
You will need blood tests every 4 to 6 weeks to check your liver function. Your heart function may also need to be checked using an electrocardiograph or ECG (sometimes called an EKG).
Store lapatinib at room temperature away from moisture and heat. Keep the bottle tightly closed when not in use.
Your doctor will determine how long to treat you with lapatinib and capecitabine or letrozole. Take your medications for the full prescribed length of time. Combination chemotherapy is usually continued unless your condition gets worse or you have serious side effects.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
What should I avoid while taking lapatinib?
Grapefruit and grapefruit juice may interact with lapatinib and lead to unwanted side effects. Avoid the use of grapefruit products while taking lapatinib.
What are the possible side effects of lapatinib?
Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Lapatinib can cause severe or fatal liver problems. Call your doctor right away if you have: upper stomach pain, itching, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).
Also call your doctor at once if you have:
- a headache with chest pain and severe dizziness, fainting, fast or pounding heartbeats;
- severe or ongoing diarrhea;
- new or worsening cough, wheezing, chest pain, feeling short of breath; or
-
severe skin reaction --fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.
Common side effects may include:
- indigestion, loss of appetite;
- nausea, vomiting, diarrhea;
- rash, itching, dry skin;
- pain or redness on the palms of your hands or the soles of your feet;
- problems with your fingernails or toenails;
- feeling weak or tired;
- nosebleeds, mouth sores;
- thinning hair; or
- headache.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What other drugs will affect lapatinib?
Tell your doctor about all your current medicines and any you start or stop using, especially:
- an antacid or stomach acid reducer such as Prilosec or Nexium;
- an antibiotic or antifungal medicine;
- an antidepressant;
- heart or blood pressure medication;
- medicine to treat HIV or AIDS;
- seizure medication; or
- St. John's wort.
This list is not complete. Other drugs may interact with lapatinib, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.
Where can I get more information?
Your doctor or pharmacist can provide more information about lapatinib.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
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