Lapatinib (By mouth)

Lapatinib (la-PA-ti-nib)

Treats breast cancer.

Brand Name(s):

Tykerb

When This Medicine Should Not Be Used:

How to Use This Medicine:

Tablet

• Your doctor will tell you how much medicine to use. Do not use more than directed.
• Take this medicine at least 1 hour before or 1 hour after a meal. Take all the tablets at the same time.
• This medicine is given together with capecitabine or letrozole. Follow your doctor's instructions on when to take these medicines.
• Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.
• Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
• Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

• Some foods and medicines can affect how lapatinib works. Tell your doctor if you are using any of the following:
  • Dexamethasone, digoxin, midazolam, nefazodone, paclitaxel, St John's wort
  • Blood pressure medicine
  • Medicine to treat heart rhythm problems
  • Medicine to treat an infection (including clarithromycin, itraconazole, ketoconazole, rifabutin, rifampin, rifapentine, voriconazole)
  • Medicine to treat HIV infection (including atazanavir, indinavir, nelfinavir, ritonavir, saquinavir, telithromycin)
  • Medicine to treat seizures (including carbamazepine, phenobarbital, phenytoin)
• Do not eat grapefruit or drink grapefruit juice while you are using this medicine.

Warnings While Using This Medicine:

• This medicine may cause birth defects if either partner is using it during conception or pregnancy. Tell your doctor right away if you or your partner becomes pregnant. Use an effective form of birth control during treatment with this medicine and for 1 week after the last dose. Male patients with female partners should use an effective form of birth control during treatment and for 1 week after the last dose.
• Do not breastfeed during treatment with this medicine and for 1 week after the last dose.
• Tell your doctor if you have liver disease, heart disease, heart rhythm problems (including QT prolongation), electrolyte imbalance, or lung disease.
• This medicine may cause the following problems:
  • Heart problems, including changes in heart rhythm
  • Liver problems
  • Lung problems (including interstitial lung disease or pneumonitis)
  • Serious skin reactions
• 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 do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
• Keep all medicine out of the reach of children. Never share your medicine with anyone.

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
• Blistering, peeling, or red skin rash
• Chest pain, cough, trouble breathing
• Dark urine or pale stools, nausea, vomiting, loss of appetite, stomach pain, yellow skin or eyes
• Dizziness, lightheadedness, unusual tiredness
• Fast, slow, pounding, or uneven heartbeat
• Severe diarrhea or diarrhea with cramps, nausea, vomiting, or fever

If you notice these less serious side effects, talk with your doctor:

• Dry skin
• Pain in the back, arms, or legs
• Hair loss or thinning of hair
• Mild diarrhea, nausea, or vomiting, stomach upset

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 4/23/2024