Classification: Tyrosine Kinase Inhibitors
Lapatinib belongs to a class of drugs known as tyrosine kinase inhibitors. Tyrosine kinase inhibitors are designed to block the action of a specific enzyme called tyrosine kinase. This enzyme plays a big role in the function of cells, and is active in cancer cells to promote tumor growth and progression. Lapatinib works to inhibit the function of two types of tyrosine kinases: epidermal growth factor receptor (EGFR) and Her2. EGFR is over expressed in several types of tumors and Her2 is over expressed in about 25-30% of all breast cancers. By blocking the function of these tyrosine kinases, lapatinib may prevent cancer cells from dividing and growing.
How to Take Lapatinib
Lapatinib is taken in a tablet form, by mouth, once a day. The dose will consist of several tablets. It should be taken on an empty stomach, one hour before or one hour after a meal, with a full glass of water. Take lapatinib at around the same time every day. If you miss a dose, do not double the next dose to make up for the missed dose.
The blood levels of this medication can be affected by certain foods and medications, so they should be avoided. These include: grapefruit, grapefruit juice, verapamil, ketoconazole, rifampin, phenytoin, St. John’s wort, and modafanil. Be sure to tell your healthcare provider about all medications and supplements you take.
Storage and Handling
Store this medication at room temperature in the original container. If you prefer to use a pillbox, discuss this with your oncology pharmacist. Ask your oncology team where to return any unused medication for disposal. Do not flush down the toilet or throw in the trash.
Where do I get this medication?
Lapatinib is available through select specialty pharmacies. Your oncology team will work with your prescription drug plan to identify an in-network specialty pharmacy for distribution of this medication and shipment directly to your home.
This medication may be covered under your prescription drug plan. Patient assistance may be available to qualifying individuals without prescription drug coverage. Co-pay assistance from private third party foundations may be available. Your healthcare team can help you access available resources.
Possible Side Effects of Lapatinib
There are a number of things you can do to manage the side effects of Lapatinib. Talk to your doctor or nurse about these recommendations. They can help you decide what will work best for you. These are some of the most common side effects:
Nausea and/or Vomiting
Talk to your doctor or nurse so they can prescribe medications to help you manage nausea and vomiting. In addition, dietary changes may help. Avoid things that may worsen the symptoms, such as heavy or greasy/fatty, spicy or acidic foods (lemons, tomatoes, oranges). Try antacids, (e.g. milk of magnesia, calcium tablets such as Tums), saltines, or ginger ale to lessen symptoms.
Call your doctor or nurse if you are unable to keep fluids down for more than 12 hours or if you feel lightheaded or dizzy at any time.
Diarrhea is a common side effect of lapatinib and is potentially dangerous because it can lead to serious dehydration. Diarrhea can be defined as an increase in the number of bowel movements you have in a day. Your healthcare team will tell you how to take loperamide (an anti-diarrheal medication), which you should start taking as soon as diarrhea develops. Notify your healthcare team if the diarrhea does not stop on this medication so they can help you better manage this side effect.
Your oncology team can recommend medications to relieve diarrhea. Also, try eating low-fiber, bland foods, such as white rice and boiled or baked chicken. Avoid raw fruits, vegetables, whole grain breads, cereals and seeds. Soluble fiber is found in some foods and absorbs fluid, which can help relieve diarrhea. Foods high in soluble fiber include: applesauce, bananas (ripe), canned fruit, orange sections, boiled potatoes, white rice, products made with white flour, oatmeal, cream of rice, cream of wheat, and farina. Drink 8-10 glasses on non-alcoholic, un-caffeinated fluid a day to prevent dehydration.
Fatigue is very common during cancer treatment and is an overwhelming feeling of exhaustion that is not usually relieved by rest. While on cancer treatment, and for a period after, you may need to adjust your schedule to manage fatigue. Plan times to rest during the day and conserve energy for more important activities. Exercise can help combat fatigue; a simple daily walk with a friend can help. Talk to your healthcare team for helpful tips on dealing with this side effect.
Nail and Skin Changes
Lapatinib has some unique nail and skin side effects that you may develop. Patients may develop a rash. While this rash may look like acne, it is not, and should not be treated with acne medications. The rash may appear red, swollen, crusty, dry and feel sore. You may also develop very dry skin, which may crack, be itchy or become flaky or scaly. The rash typically starts in the first week of treatment, but can occur at any time during treatment. Tips for managing your skin include:
While receiving lapatinib, you may develop an inflammation of the skin around the nail bed/cuticle areas of toes or fingers, which is called paronychia. It can appear red, swollen or pus filled. Nails may develop "ridges" in them or fall off. You may also develop cuts or cracks that look like small paper cuts in the skin on your toes, fingers or knuckles. These side effects may appear several months after starting treatment, but can last for many months after treatment stops.
Decrease in Appetite
Nutrition is an important part of your care. Cancer treatment can affect your appetite and, in some cases, the side effects of treatment can make eating difficult. Ask your nurse about nutritional counseling services at your treatment center to help with food choices.
??Hand Foot Syndrome
Hand and foot syndrome (HFS) is a skin reaction that appears on the palms of the hands and/or the soles of the feet as a result of certain chemotherapy agents being absorbed by the skin cells. HFS can begin as a mild tingling, numbness, pins-and-needles feeling, or pain or swelling of the hands and/or feet. This can then progress to painful swelling, blistering or peeling skin that can interfere with your ability to do normal activities. Be sure to let your oncology team know right away if you notice these symptoms, as they may need to adjust the chemotherapy dose or take a break to allow the skin to heal. Some tips to help prevent HFS include:
Lung Changes and Pneumonitis
Patients can develop an inflammation of the lungs (called pneumonitis) or interstitial lung disease while taking this medication. Notify your healthcare provider right away if you develop any new or worsening symptoms, including shortness of breath, trouble breathing, cough or fever.
This medication can cause liver toxicity, which your doctor may monitor for using blood tests called liver function tests. Notify your healthcare provider if you notice yellowing of the skin or eyes, your urine appears dark or brown or pain in your abdomen, as these can be signs of liver toxicity.
Lapatinib is known to cause cardiac (heart) dysfunction, including severe heart failure (congestive heart failure). Patients should have their heart function tested prior to starting this therapy and during therapy if any symptoms arise. If heart function decreases, lapatinib should be stopped. You should report to your healthcare team any symptoms of cardiac dysfunction, including: feeling like your heart is racing or pounding, dizziness, unusual tiredness, lightheadedness or shortness of breath.
Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant or father a child while on this medication. Effective birth control is necessary during treatment. Even if your menstrual cycle stops or you believe you are not producing sperm, you could still be fertile and conceive. You should consult with your healthcare team before breastfeeding while receiving this medication.
OncoLink is designed for educational purposes only and is not engaged in rendering medical advice or professional services. The information provided through OncoLink should not be used for diagnosing or treating a health problem or a disease. It is not a substitute for professional care. If you have or suspect you may have a health problem or have questions or concerns about the medication that you have been prescribed, you should consult your health care provider.
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