Used with capecitabine (Xeloda®) to treat advanced or metastatic HER2-receptor positive breast cancer (breast cancer that has already spread) in patients who have already received other medicines. It is also used with letrozole (Femara®) to treat postmenopausal women with hormone-receptor positive and HER2-receptor positive metastatic breast cancer.
There may be other brand names for this medicine.
When This Medicine Should Not Be Used
You should not use this medicine if you have had a severe allergic reaction to lapatinib, or if you are pregnant or planning to become pregnant.
How to Use This Medicine
- Medicines used to treat cancer are very strong and can have many side effects. Before receiving this medicine, make sure you understand all the risks and benefits. It is important for you to work closely with your doctor during your treatment.
- Your doctor will tell you how much of this medicine to use and how often. Do not use more medicine or use it more often than your doctor tells you to.
- This medicine should be taken at least one hour before or one hour after a meal. All of the lapatinib tablets are taken together as one dose each day. Follow your doctor's instructions on when to take this medicine.
- This medicine is given together with capecitabine or letrozole. Take capecitabine with food or within 30 minutes after food. It is important that you take each medicine at the right time. Follow your doctor's instructions on when to take these medicines.
- You may also receive medicines to help prevent diarrhea, nausea, and vomiting.
- This medicine comes with patient instructions. Read and follow these instructions carefully. Ask your doctor or pharmacist if you have any questions.
If a dose is missed:
- If you miss a dose or forget to use your medicine, use it as soon as you can. If it is almost time for your next dose, wait until then to use the medicine and skip the missed dose. Do not use extra medicine to make up for a missed dose.
How to Store and Dispose of This Medicine
- Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
- Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any leftover medicine after you have finished your treatment. You will also need to throw away old medicine after the expiration date has passed.
- Keep all medicine away from children and never share your medicine with anyone.
Drugs and Foods to Avoid
Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.
- Make sure your doctor knows if you are using certain antibiotics (such as clarithromycin, erythromycin, levofloxacin, rifabutin, rifampin, rifapentine, telithromycin, Avelox®, Biaxin®, Ketek®, Levaquin®, or Rifadin®), medicine to treat fungal infections (such as itraconazole, ketoconazole, voriconazole, Nizoral®, Sporanox®, or Vfend®), or medicine to treat HIV or AIDS (such as atazanavir, indinavir, nelfinavir, ritonavir, saquinavir, Crixivan®, Fortovase®, Invirase®, Norvir®, Reyataz®, or Viracept®).
- Tell your doctor if you are using certain blood pressure medicines (such as diltiazem, nifedipine, verapamil, Cartia®, Norvasc®, or Tiazac®), medicine that weaken the immune system (such as cyclosporine, sirolimus, tacrolimus, Gengraf®, Neoral®, Prograf®, Rapamune®, or Sandimmune®), medicine for seizures (such as carbamazepine, phenobarbital, phenytoin, Dilantin®, or Tegretol®), medicine to treat depression (such as amitriptyline, fluoxetine, nefazodone, Prozac®, or Serzone®), steroid medicines (such as dexamethasone, Decadron®, or Hexadrol®), or St. John's Wort.
- Make sure your doctor knows if you are using arsenic trioxide (Trisenox®), digoxin (Lanoxin®), dofetilide (Tikosyn®), midazolam (Versed®), paclitaxel (Taxol®), ergot medicine (such as dihydroergotamine, ergotamine, Cafergot®, Ergomar®, Migranal®, or Wigraine®), medicine to treat mental illness (such as haloperidol, mesoridazine, pimozide, prochlorperazine, quetiapine, thioridazine, ziprasidone, Compazine®, Geodon®, Haldol®, Mellaril®, Orap®, Serentil®, or Seroquel®), or narcotic pain medicines (such as alfentanil, fentanyl, Alfenta® or Sublimaze®).
- Do not eat grapefruit or drink grapefruit juice while you are using this medicine.
Warnings While Using This Medicine
- Your unborn baby could be harmed if you use this medicine while you are pregnant. Use an effective form of birth control to keep from getting pregnant. Tell your doctor right away if you think you have become pregnant while using the medicine.
- Make sure your doctor knows if you are breastfeeding, or if you have liver disease, heart disease, heart rhythm problems (such as QT prolongation), or low magnesium or potassium in your blood.
- Serious heart problems can occur with this medicine. Check with your doctor right away if you are having fast, pounding, or uneven heartbeats; shortness of breath; or unusual tiredness or weakness.
- This medicine can cause changes in heart rhythms, such as a condition called QT prolongation. It may change the way your heart beats and cause fainting or serious side effects in some patients. Tell your doctor right away if you have any symptoms of heart rhythm problems, such as fast, pounding, or uneven heartbeats.
- Stop using this medicine and check with your doctor right away if you have pain or tenderness in the upper stomach; pale stools; dark urine; a loss of appetite; nausea; unusual tiredness or weakness; or yellow eyes or skin. These could be symptoms of a serious liver problem.
- This medicine causes diarrhea, nausea, and vomiting in most people. Ask your doctor about ways to control these side effects.
- Stop using this medicine and check with your doctor right away if you start having breathing problems, shortness of breath, a cough, chest pain, fever, or chills. These could be symptoms of a serious lung disease.
- Your doctor will need to check your progress at regular visits while you are using this medicine. Be sure to keep all appointments. Blood tests may be needed to check for unwanted effects.
Possible Side Effects While Using This Medicine
Call your doctor right away if you notice any of these side effects:
- Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
- Chest pain or shortness of breath.
- Dark-colored urine or pale stools.
- Fast, slow, pounding, or uneven heartbeat.
- Fever, chills, or cough.
- Nausea, vomiting, loss of appetite, or pain in your upper stomach.
- Severe diarrhea.
- Unusual tiredness or weakness.
- Yellowing of your skin or the whites of your eyes.
If you notice these less serious side effects, talk with your doctor:
- Dry skin or mild skin rash.
- Hair loss.
- Loss of appetite.
- Mild diarrhea, nausea, vomiting, or upset stomach.
- Nail pain, infection and swelling of the cuticles.
- Pain in the back, arms, or legs.
- Red, painful hands and feet.
- Sores or white patches on your lips, mouth, or throat.
- Trouble sleeping.