Lapatinib (Tykerb®)

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About This Drug

Lapatinib is used to treat cancer. It is given orally (by mouth).

Possible Side Effects

  • Nausea and vomiting (throwing up)
  • Diarrhea (loose bowel movements)
  • Tiredness
  • Rash
  • Hand-and-foot syndrome. The palms of your hands or soles of your feet may tingle, become numb,
    painful, swollen, or red.

Note: Each of the side effects above was reported in 20% or greater of patients treated with lapatinib in combination with either capecitabine, letrozole or trastuzumab. Side effects may vary dependent on which combination is administered. Not all possible side effects are included above.

Warnings and Precautions

  • Severe diarrhea which can be life-threatening
  • Abnormal heart beat and changes in your heart function
  • Scarring of the lungs that causes stiffness in the lungs and/or inflammation (swelling of the lungs). You may have a dry cough or trouble breathing.
  • Severe allergic skin reaction which can be life-threatening. You may develop blisters on your skin that are filled with fluid or a severe red rash all over your body that may be painful.
  • Severe changes in your liver function, which can cause liver failure and be life-threatening

Note: Some of the side effects above are very rare. If you have concerns and/or questions, please discuss them with your medical team.

Important Information

  • It is important that you notify your doctor and/or nurse at the first sign of diarrhea, so they can provide you with anti-diarrhea medication and give you further instructions. Notify your doctor and/or nurse if you are taking anti-diarrhea medication and your symptoms have not improved, or are worsening.

How to Take Your Medication

  • Take this drug by mouth without food, at least 1 hour before you eat or 1 hour after you eat. Lapatinib is usually given with another medicine. Follow your doctor’s instructions carefully for how to take lapatinib and how to take the other medicine.
  • Missed dose: If you vomit or miss a dose, take your next dose at the regular time, and contact your doctor. Do not take 2 doses at the same time and do not double up on the next dose.
  • Handling: Wash your hands after handling your medicine; your caretakers should not handle your medicine with bare hands and should wear latex gloves.
  • This drug may be present in the saliva, tears, sweat, urine, stool, vomit, semen, and vaginal secretions. Talk to your doctor and/or your nurse about the necessary precautions to take during this time.
  • Storage: Store this medicine in the original container at room temperature.
  • Disposal of unused medicine: Do not flush any expired and/or unused medicine down the toilet or drain unless you are specifically instructed to do so on the medication label. Some facilities have take-back programs and/or other options. If you do not have a take-back program in your area, then please discuss with your nurse or your doctor how to dispose of unused medicine.

Treating Side Effects

  • Manage tiredness by pacing your activities for the day.
  • Be sure to include periods of rest between energy-draining activities.
  • Drink plenty of fluids (a minimum of eight glasses per day is recommended).
  • If you throw up or have loose bowel movements, you should drink more fluids so that you do not become dehydrated (lack of water in the body from losing too much fluid).
  • If you get diarrhea, eat low-fiber foods that are high in protein and calories and avoid foods that can irritate your digestive tracts or lead to cramping.
  • Ask your nurse or doctor about medicine that can lessen or stop your diarrhea.
  • To help with nausea and vomiting, eat small, frequent meals instead of three large meals a day. Choose foods and drinks that are at room temperature. Ask your nurse or doctor about other helpful tips and medicine that is available to help or stop lessen these symptoms.
  • If you get a rash do not put anything on it unless your doctor or nurse says you may. Keep the area around the rash clean and dry. Ask your doctor for medicine if your rash bothers you.
  • Avoid sun exposure and apply sunscreen routinely when outdoors.

Food and Drug Interactions

  • Avoid grapefruit or drink grapefruit juice while taking this medicine. Grapefruit and grapefruit juice may raise the levels of lapatinib in your body. This could make side effects worse.
  • Check with your doctor or pharmacist about all other prescription medicines and over-the-counter medicines and dietary supplements (vitamins, minerals, herbs and others) you are taking before starting this medicine as there are known drug interactions with lapatinib. Also, check with your doctor or pharmacist before starting any new prescription or over-the-counter medicines, or dietary supplement to make sure that there are no interactions.
  • Avoid the use of St. John’s Wort while taking lapatinib as this may lower the levels of the drug in your body, which can make it less effective.

When to Call the Doctor

Call your doctor or nurse if you have any of these symptoms and/or any new or unusual symptoms:

  • Fever of 100.4° F (38° C) or higher
  • Chills
  • Tiredness that interferes with your daily activities
  • Feeling dizzy or lightheaded
  • Feeling that your heart is beating in a fast or not normal way (palpitations)
  • Pain in your chest
  • Trouble breathing
  • Dry cough
  • Flu-like symptoms: fever, headache, muscle and joint aches, and fatigue (low energy, feeling weak)
  • Diarrhea, 4 times in one day or diarrhea with lack of strength or a feeling of being dizzy
  • Nausea that stops you from eating or drinking and/or is not relieved by prescribed medicines
  • Throwing up more than 3 times a day
  • Signs of possible liver problems: dark urine, pale bowel movements, bad stomach pain, feeling very tired and weak, unusual itching, or yellowing of the eyes or skin
  • New rash and/or itching
  • Rash that is not relieved by prescribed medicines
  • Painful, red, or swollen areas on your hands or feet
  • Numbness and/or tingling of your hands and/or feet
  • If you think you may be pregnant or may have impregnated your partner

Reproduction Warnings

  • Pregnancy warning: This drug can have harmful effects on the unborn baby. Women of childbearing potential should use effective methods of birth control during your cancer treatment and for 1 week after treatment. Men with female partners of childbearing potential should use effective methods of birth control during your cancer treatment and for 1 week after your cancer treatment. Let your doctor know right away if you think you may be pregnant or may have impregnated your partner.
  • Breastfeeding warning: Women should not breastfeed during treatment and for 1 week after treatment because this drug could enter the breast milk and cause harm to a breastfeeding baby.
  • Fertility warning: Human fertility studies have not been done with this drug. Talk with your doctor or nurse if you plan to have children. Ask for information on sperm or egg banking.

Revised March 2019

This patient information was developed by Via Oncology, LLC © 2018. This information is not intended to be used as a substitute for professional medical advice, diagnosis, or treatment. You should not rely entirely on this information for your health care needs. Ask your own doctor or health care provider any specific medical questions that you have.

CLIENT acknowledges that the Via Pathways and Via Portal are information management tools only, and that Via Oncology, LLC has not represented the Via Pathways or Via Portal as having the ability to diagnose disease, prescribe treatment, or perform any other tasks that constitute the practice of medicine. The clinical information contained in the Via Pathways and Via Portal are intended as a supplement to, and not a substitute for, the knowledge, expertise, skill, and judgment of physicians, pharmacists and other healthcare professionals involved with patient care at CLIENT facilities.