Imatinib (patient information)

Why this medication is prescribed

Imatinib is used to treat certain types of leukemia (cancer that begins in the white blood cells) and other cancers of the blood cells. Imatinib is also used to treat 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 protein-tyrosine 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 this medication should 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.

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 mL (a little less than 2 ounces) of liquid for each 100 mg tablet and 100 mL (a little less than 4 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 two 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.

Other uses for this medicine

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

Special precautions

Before taking imatinib:

• tell your doctor and pharmacist if you are allergic to imatinib or any other medications.
• tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, and nutritional supplements you are taking or plan to take. Be sure to mention any of the following: acetaminophen (Tylenol); certain antibiotics including erythromycin (E.E.S., E-Mycin, Erythrocin), clarithromycin (Biaxin), and rifampin (Rifadin, in Rifamate); anticoagulants ('blood thinners') such as warfarin (Coumadin); antifungals such as ketoconazole (Nizoral) and itraconazole (Sporanox); calcium channel blockers such as amlodipine (Norvasc, in Caduet), diltiazem (Cardizem, Tiazac), felodipine (Plendil), isradipine (Dynacirc), nicardipine (Cardene), nifedipine (Adalat, Procardia, others), nimodipine (Nimotop), nisoldipine (Sular), or verapamil (Calan, Covera, Isoptin, Verelan); cholesterol-lowering medications (statins) such as atorvastatin (Lipitor), lovastatin (Mevacor), and simvastatin (Zocor); cyclosporine (Neoral, Sandimmune); dexamethasone; hormonal contraceptives (birth control pills, patches, rings, injections or implants); pimozide (Orap); medications for anxiety; medications for seizures such as carbamazepine (Tegretol), phenobarbital, and phenytoin (Dilantin); sedatives; sleeping pills; and tranquilizers. Other medications may also interact with imatinib, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor what herbal products you are taking, especially St. John's wort.
• tell your doctor if you have or have ever had high blood pressure a heart attack; an irregular heartbeat; diabetes; or heart, lung, thyroid, or liver disease. Also tell your doctor if you smoke, if you use street drugs, and if you drink or have ever drunk large amounts of alcohol.
• tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while you are taking imatinib. 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 breast-feeding. You should not breast-feed while you are taking imatinib.
• talk to your doctor about what you should do if you develop diarrhea during your treatment. Do not take any medications to treat diarrhea without talking to your doctor.

Special dietary instructions

Talk to your doctor about drinking grapefruit juice or eating grapefruit while taking this medication.

What to do if you forget 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.

Side effects

Minor side effects

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

• diarrhea
• constipation
• gas
• nausea
• vomiting
• loss of appetite
• indigestion
• joint pain
• muscle cramps
• depression
• anxiety
• night sweats
• teary eyes

Severe side effects

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

• puffiness under the eyes
• swelling of the hands, feet, ankles, or lower legs
• weight gain
• shortness of breath
• fast, irregular, or pounding heartbeat
• difficulty falling asleep or staying asleep
• fainting
• coughing up pink or bloody mucus
• increased urination, especially at night
• chest pain
• fever
• rash or blisters
• yellowing of the skin or eyes
• blood in the stool
• unusual bruising or bleeding
• sore throat, fever, chills, and other signs of infection
• excessive tiredness or weakness
• headache
• dizziness

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

Storage conditions needed for 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). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

In case of emergency/overdose

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

Symptoms of overdose may include:

• muscle cramps
• swollen or bloated stomach

Other information

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.

Brand names

• Gleevec®