Imatinib

WHY is this medicine prescribed?

Imatinib is used to treat certain types of leukemia (cancer that begins in the white blood cells) and other cancers and disorders of the blood cells. Imatinib is also used to treat certain types of gastrointestinal stromal tumors (GIST; a type of tumor that grows in the walls of the digestive passages and may spread to other parts of the body). Imatinib is also used to treat dermatofibrosarcoma protuberans (a tumor that forms under the top layer of skin) when the tumor cannot be removed surgically, has spread to other parts of the body, or has come back after surgery. Imatinib is in a class of medications called kinase inhibitors. It works by blocking the action of the abnormal protein that signals cancer cells to multiply. This helps stop the spread of cancer cells.

HOW should this medicine be used?

Imatinib comes as a tablet to take by mouth. It is usually taken with a meal and a large glass of water once or twice a day. Take imatinib at around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take imatinib exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Swallow the tablets whole; do not chew or crush them. If you touch or come into direct contact with a crushed tablet, wash the area thoroughly.

If you are unable to swallow imatinib tablets, you may place all of the tablets that you need for one dose into a glass of water or apple juice. Use 50 milliliters (a little less than 2 ounces) of liquid for each 100-mg tablet and 200 milliliters (a little less than 7 ounces) of liquid for each 400-mg tablet. Stir with a spoon until the tablets crumble completely and drink the mixture immediately.

If your doctor has told you to take 800 mg of imatinib, you should take 2 of the 400-mg tablets. Do not take 8 of the 100-mg tablets. The tablet coating contains iron, and you will receive too much iron if you take 8 of the 100-mg tablets.

Your doctor may increase or decrease your dose of imatinib during your treatment. This depends on how well the medication works for you and on the side effects you experience. Talk to your doctor about how you are feeling during your treatment. Continue to take imatinib even if you feel well. Do not stop taking imatinib without talking to your doctor.

Are there OTHER USES for this medicine?

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What SPECIAL PRECAUTIONS should I follow?

Before taking imatinib,

• tell your doctor and pharmacist if you are allergic to imatinib, any other medications, or any of the ingredients in imatinib tablets. Ask your pharmacist for a list of the ingredients.
• tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take while taking imatinib. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• the following herbal product may interact with imatinib: St. John's wort. Be sure to let your doctor and pharmacist know that you are taking this medication before you start taking imatinib. Do not start this medication while taking imatinib without discussing with your healthcare provider.
• tell your doctor if you have or have ever had heart, lung, thyroid, kidney, or liver disease.
• tell your doctor if you are pregnant or plan to become pregnant. You will have to take a pregnancy test before starting treatment, You should not become pregnant while you are taking imatinib and for 14 days after your final dose. Talk to your doctor about birth control methods that you can use during your treatment. If you become pregnant while taking imatinib, call your doctor. Imatinib may harm the fetus.
• tell your doctor if you are breastfeeding. You should not breastfeed while you are taking imatinib and for one month after your final dose.
• if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking imatinib.
• you should know that imatinib may make you dizzy, drowsy, or cause blurred vision. Do not drive a car or operate machinery until you know how this medication affects you.

What SPECIAL DIETARY instructions should I follow?

Do not eat grapefruit or drink grapefruit juice while taking this medication.

What should I do IF I FORGET to take a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What SIDE EFFECTS can this medicine cause?

Imatinib may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• diarrhea
• nausea
• vomiting
• change in the way things taste
• mouth sores or swelling inside the mouth
• loss of appetite
• weight loss
• heartburn or indigestion
• dry mouth
• headache
• joint swelling or pain
• bone pain
• muscle cramps, spasms, or pain
• tingling, burning. or prickling feeling on the skin
• difficulty falling asleep or staying asleep
• sweating
• teary eyes
• pink eye
• flushing
• dry skin
• rash
• itching
• nail changes
• hair loss

Some side effects can be serious. If you experience any of these symptoms call your doctor immediately:

• swelling around the eyes
• swelling of the hands, feet, ankles, or lower legs
• sudden weight gain
• shortness of breath
• fast, irregular, or pounding heartbeat
• coughing up pink or bloody mucus
• increased urination, especially at night
• chest pain
• peeling, blistering, or shedding skin
• yellowing of the skin or eyes
• blood in the stool
• unusual bruising or bleeding
• flu-like symptoms, sore throat, fever, chills, and other signs of infection
• excessive tiredness or weakness
• abdominal pain or bloating

Imatinib may slow growth in children. Your child's doctor will watch his or her growth carefully. Talk to your child's doctor about the risks of giving imatinib to your child.

Imatinib may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

What should I know about STORAGE and DISPOSAL of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. https://www.upandaway.org

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (https://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

What should I do in case of OVERDOSE?

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Symptoms of overdose may include the following:

• nausea
• vomiting
• diarrhea
• rash
• swelling
• extreme tiredness
• muscle cramps or spasms
• abdominal pain
• headache
• loss of appetite

What OTHER INFORMATION should I know?

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your body's response to imatinib.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS^® Patient Medication Information™. © Copyright, 2024. The American Society of Health-System Pharmacists^®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Selected Revisions: March 15, 2020.