Last Modified: August 22, 2011
Classification: Tyrosine Kinase Inhibitor
Imatinib works by blocking signals within cancer cells, which prevents a series of chemical reactions that allow the cell to grow and divide. The growth of cells in our body are controlled by growth factors, which attach themselves to the surface of cells, triggering a series of chemical reactions that cause the cell to grow and divide. Cancer cells do not function properly. These cells are able to grow and divide even when growth factors are not present. Imatinib is able to attach to the faulty cell and prevent the "grow and divide" signal, thus stopping the reproduction of cancer cells.
How to Take Imatinib
Imatinib comes in 100mg and 400mg tablets. The dose you will take depends upon your type of cancer. Take each dose with a glass of water and a meal. Do not eat grapefruit or drink grapefruit juice while taking imatinib, as this can interfere with how the medication is absorbed by your body. Take imatinib at around the same time(s) every day.
Certain medications can affect are broken down by the same enzymes as imatinib. This can cause the blood levels of these medications, or the blood levels of imatinib, to be higher or lower than expected. These medications include: acetaminophen (Tylenol), birth control pills, warfarin (Coumadin), certain antibiotics, St. John's Wort, and anticonvulsants (these prevent seizures).
Possible Side Effects of Imatinib
There are a number of things you can do to manage the side effects of Imatinib. 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:
Swelling Around the Eyes or of the Lower Legs
Some patients experience swelling around the eyes or in the legs or feet due to fluid retention in the tissues. Fluid can also build up in the lungs or heart. Notify your healthcare team if you develop swelling, have unexpected weight gain, chest pain or shortness of breath. Your doctor may prescribe a diuretic (medication which causes you to produce more urine) to help get rid of some of the excess fluid.
Nausea and/or Vomiting
Taking the medication with a meal and a large glass of water can help. 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. If you continue to have nausea or vomiting, notify your doctor or nurse so they can help you manage this side effect. Talk to them about dividing your dose in half and taking it twice a day. Read the Nausea & Vomiting Tip Sheet for more suggestions.
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.
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 that absorbs fluid and can help relieve diarrhea. Foods high in soluble fiber include: applesauce, bananas (ripe), canned fruit, orange and grapefruit sections, boiled potatoes, white rice and 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. Read Low Fiber Diet for Diarrhea for more tips.
Some patients may develop a rash, scaly skin, or red itchy bumps. Use an alcohol free moisturizer on your skin and lips; avoid moisturizers with perfumes or scents. Your doctor or nurse can recommend a topical medication if itching is bothersome. If your skin does crack or bleed, be sure to keep the area clean to avoid infection. For more suggestions, read the Nail and Skin Care Tip Sheet.
Some patients develop mild muscle aches, cramps, spasms or pain in their legs or feet while taking imatinib. Let your healthcare team know. These aches and cramps can usually be managed with calcium and magnesium supplements or mild pain medications, such as ibuprofen.
Sexual and Reproductive Changes
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 your sperm is affected. Some patients have been able to stop therapy in order to have children. Discuss these options with your oncology team. See OncoLink's section on sexuality for helpful tips for dealing with these side effects.
Low White Blood Cell Count (Leukopenia or Neutropenia)
White blood cells (WBC) are important for fighting infection. While receiving treatment, your WBC count can drop, putting you at a higher risk of getting an infection. You should let your doctor or nurse know right away if you have a fever (temperature greater than 100.4 F), sore throat or cold, shortness of breath, cough, burning with urination, or a sore that doesn't heal.
Tips to preventing infection:
- Washing hands, both yours and your visitors, is the best way to prevent the spread of infection.
- Avoid large crowds and people who are sick (i.e.: those who have a cold, fever or cough or live with someone with these symptoms).
- When working in your yard, wear protective clothing including long pants and gloves.
- Do not handle pet waste.
- Keep all cuts or scratches clean.
- Shower or bath daily and perform frequent mouth care.
- Do not cut cuticles or ingrown nails. You may wear nail polish, but not fake nails.
- Ask your doctor or nurse before scheduling dental appointments or procedures.
- Ask your doctor or nurse before you, or someone you live with, has any vaccinations.
For more suggestions, read the Neutropenia Tip Sheet.
Low Red Blood Cell Count (Anemia)
Your red blood cells are responsible for carrying oxygen to the tissues in your body. When the red cell count is low, you may feel tired or weak. You should let your doctor or nurse know if you experience any shortness of breath, difficulty breathing or pain in your chest. If the count gets too low, you may receive a blood transfusion. Read the anemia tip sheet for more information.
Low Platelet Count (Thrombocytopenia)
Platelets help your blood clot, so when the count is low you are at a higher risk of bleeding. Let your doctor or nurse know if you have any excess bruising or bleeding, including nosebleeds, bleeding gums or blood in your urine or stool. If your platelet count becomes too low, you may receive a transfusion of platelets.
- Do not use a razor to shave (an electric razor is fine).
- Avoid contact sports and activities that can result in injury or bleeding.
- Do not take aspirin (salicylic acid), non-steroidal, anti-inflammatory medications (NSAIDs) such as Motrin®, Aleve®, Advil®, etc. as these can all increase the risk of bleeding. Unless your healthcare team tells you otherwise, you may take acetaminophen (Tylenol).
- Do not floss or use toothpicks and use a soft-bristle toothbrush to brush your teeth.
Read the thrombocytopenia tip sheet for more information.
Your physician will monitor your blood counts and liver function tests frequently when you start this medication, then less frequently over time.