How does this medication work? What will it do for me?
Imatinib belongs to a family of medications called protein tyrosine kinase inhibitors. It is used to treat adults and children who have been newly diagnosed with chronic myeloid leukemia (CML). It works by affecting enzymes that play a role in certain cancer cells.
It is also used to treat adults with chronic myeloid leukemia (CML) in blast crisis (sudden attack), accelerated phase (fast growth), or chronic phase (long-term illness) after the failure of interferon-alpha therapy. Imatinib is also used to treat adults with cancerous gastrointestinal stromal tumours (GIST) that cannot be removed by surgery or that are spreading to other parts of the body.
It is used to treat adults who have been newly diagnosed with certain types of acute lymphoblastic leukemia (Philadelphia-positive – Ph+ ALL). It is also used to treat Ph+ ALL that have not responded to other medications. Imatinib is also used to treat dermatofibrosarcoma protuberans (DFSP), a cancer where tissue under the skin grows out of control, when it cannot be removed by surgery or it is spreading to other parts of the body.
Other types of cancers can also be treated with imatinib. Imatinib may also be used to treat some types of myelodysplastic/myeloproliferative diseases (MDS/MPD), aggressive systemic mastocytosis (ASM), hypereosinophilic syndrome (HES), and chronic eosinophilic leukemia (CEL). In these conditions, different types of blood cells start growing out of control.
Imatinib has been granted a notice of compliance with conditions (NOC/c) by Health Canada to treat adults who have an intermediate to high risk of GIST returning, after the tumours have been completely removed by surgery. This means that Health Canada has approved this medication to be marketed based on promising evidence of effectiveness, but additional results of studies are needed to verify its effectiveness. An NOC/c is used to allow access to products that are used to treat or prevent serious, life-threatening, or severely debilitating illness.
This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.
Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.
Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.
What form(s) does this medication come in?
Each brownish-orange, slightly biconvex, round, film-coated tablet, engraved "IMA" over score "100" on one side and "APO" on the other, contains 100 mg of imatinib.Nonmedicinal ingredients: colloidal silicon dioxide, crospovidone, hydroxypropyl cellulose, hypromellose, magnesium stearate, polyethylene glycol, ferric oxide red, and ferric oxide yellow.
Each brownish-orange, capsule-shaped, biconvex film-coated tablet, engraved "IMA" score line "400" on one side and "APO" on the other, contains 400 mg of imatinib. Nonmedicinal ingredients: colloidal silicon dioxide, crospovidone, hydroxypropyl cellulose, hypromellose, magnesium stearate, polyethylene glycol, ferric oxide red, and ferric oxide yellow.
How should I use this medication?
Treatment with imatinib should be started under the direct supervision of a physician experienced in the treatment of the conditions for which this medication is being used.
Doses for children are based on body size and will be calculated by your child’s doctor.
For newly diagnosed chronic myeloid leukemia (CML) or chronic phase CML, the usual adult dose of imatinib is 400 mg daily. The usual adult dose in accelerated phase or blast crisis CML is 600 mg daily. Depending on how you respond to the treatment and on the side effects you experience, you doctor may increase your dose to 800 mg daily.
For cancerous gastrointestinal stromal tumours (GIST), the usual adult dose ranges from 400 mg to 600 mg daily. Dose adjustments may be required depending on your response and on the side effects you experience. The usual dose for adults at intermediate to high risk of relapse of GIST is 400 mg taken once daily.
For Ph+ ALL, the usual adult dose is 600 mg daily.
For MDS/MPD in adult patients, the starting dose is 400 mg daily.
For some types of ASM, HES, or CEL, the starting dose is 100 mg daily. Depending on how you respond to the treatment and on the side effects you experience, you doctor may increase your dose to 400 mg daily.
For DFSP in adult patients, imatinib is taken as 800 mg daily. Doses of 800 mg should be taken as 400 mg twice a day, in the morning and evening.
Imatinib should be taken by mouth, with a meal and a large glass of water. Avoid drinking grapefruit juice while you are taking imatinib. Swallow the tablets whole.
If you are not able to swallow the tablet(s) whole, the tablet(s) may be dissolved in a glass of water or apple juice. Stir with a spoon to completely disintegrate. This liquid must be swallowed immediately. Rinse the glass with the same fluid and drink this as well.
Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.
It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.
Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.
Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.
Who should NOT take this medication?
Do not take this medication if you are allergic to imatinib or any ingredients of the medication.
This medication should not be used except under direct supervision by an experienced physician.
What side effects are possible with this medication?
Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.
The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.
The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.
Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.
- abdominal pain or bloating
- blurred vision
- bone pain
- changes in appetite
- difficulty sleeping
- dry mouth
- gas (flatulence)
- increased muscle tension
- increased skin sensitivity to the sun
- increased tear production
- indigestion or heartburn
- itchy, dry skin
- itchy eyes
- joint pain
- joint swelling
- loss of appetite
- muscle pain
- muscle spasms and cramps
- night sweats
- numbness or tingling of the hands of feet
- skin rash
- slowed growth in children and adolescents
- taste disturbance
- unusual hair loss or thinning
- weight loss
Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.
Check with your doctor as soon as possible if any of the following side effects occur:
- abdominal pain
- difficult or painful breathing
- hearing problems
- numb or cold toes and fingers
- severe headache
- signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
- signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don’t stop bleeding)
- signs of electrolyte imbalance (e.g., muscle pain or cramps, weakness, irregular heart beat)
- signs of fluid retention (e.g., rapid weight gain and swelling)
- signs of infection (e.g., fever, severe chills, sore throat, mouth ulcers)
- signs of kidney problems (e.g., increased urination at night, decreased urine production, blood in the urine)
- signs of liver damage (e.g., yellow skin or eyes, abdominal pain, dark urine, clay-coloured stools, loss of appetite, or nausea and vomiting)
- signs of low blood pressure (e.g., dizziness, lightheadedness)
- signs of muscle damage (e.g., muscle pain, tenderness or weakness, or brown or discoloured urine) - especially if you also have a fever or a general feeling of being unwell
- symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
- vision changes
Stop taking the medication and seek immediate medical attention if any of the following occur:
- signs of a serious allergic reaction (e.g., abdominal cramps, swelling of lips, hives, difficulty breathing, nausea, vomiting, swelling face and throat)
- chest pain
- irregular or pounding heartbeat
- severe abdominal pain
- severe painful swelling of an extremity (i.e., arms or legs)
- severe skin reactions on a large area of the body or on the lips (e.g., ulcers, blisters, pain, redness, severe rash, skin peeling)
- shortness of breath
- signs of bleeding in the stomach (e.g., bloody, black, or tarry stools, coughing up blood, vomiting blood or material that looks like coffee grounds)
- signs of fluid in the lungs (e.g., cough, chest pain, difficulty breathing, coughing up blood)
- signs of heart attack (e.g., sudden chest pain or pain radiating to the back, down the arm, or in the jaw; sensation of fullness of the chest; nausea; vomiting; sweating; anxiety)
- signs of stroke due to bleeding into the brain (e.g., sudden or severe headache; sudden loss of coordination; vision changes; sudden slurring of speech; or unexplained weakness, numbness, or pain in arm or leg)
- symptoms of heart failure (e.g., leg swelling, chest pain, or shortness of breath)
Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.
Are there any other precautions or warnings for this medication?
Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Anemia: Imatinib may cause low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired, or pale skin, contact your doctor as soon as possible.
Your doctor will do blood tests regularly to monitor the number of specific types of blood cells, including red blood cells, in your blood.
Bleeding: Imatinib may cause a reduced number of platelets in the blood, which can make it difficult to stop cuts from bleeding. If you notice any signs of bleeding, such as frequent nosebleeds, unexplained bruising, or black and tarry stools, notify your doctor as soon as possible. Your doctor will order routine blood tests to make sure potential problems are caught early.
Drowsiness/reduced alertness: This medication is not expected to make you drowsy and impair your ability to drive or use machinery. However, it may make some people feel weak. Do not drive or use machinery until you know how this medication affects you.
Fluid retention: This medication can cause serious fluid retention. If you experience unexpected rapid weight gain or swelling in your feet, ankles, lower legs, or hands, contact your doctor immediately. Your doctor will weigh and monitor you regularly for signs of fluid retention while you are taking this medication.
Grapefruit juice: Grapefruit juice affects how imatinib is removed from the body and may cause too much of the medication to build up in the body. Do not drink grapefruit juice while taking this medication.
Heart problems and heart failure: Rarely, heart problems including heart failure, have been reported with the use of imatinib. If you are at risk for heart problems such as heart failure (e.g., people with high blood pressure, diabetes, and coronary artery disease), discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Contact your doctor immediately if you have symptoms of heart failure such as leg swelling, chest pain, or shortness of breath.
Infection: As well as killing cancer cells, imatinib can reduce the number of cells that fight infection in the body (white blood cells). If possible, avoid contact with people with contagious infections. Tell your doctor immediately if you notice signs of an infection, such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness. Your doctor will do blood tests regularly to monitor the number of specific types of blood cells in your blood.
Kidney function: If you have kidney problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Liver function: Imatinib may affect liver function. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function with blood tests regularly while you are taking this medication.
Muscle effects: In rare cases, serious muscle damage has been associated with the use of this medication. Report any unexplained muscle pain, tenderness, weakness or cramps, or any brown or discoloured urine to your doctor immediately, particularly if you are also experiencing malaise (a general feeling of being unwell) or fever.
Stomach problems: Imatinib may cause stomach irritation or bleeding. To reduce stomach irritation, take this medication with food and a large glass of water. If you experience signs of stomach bleeding (e.g., severe stomach pain, black stools, vomiting blood, dizziness), get immediate medical attention.
Thyroid: If you have hypothyroidism due to removal of thyroid gland, you may need closer monitoring of your thyroid levels. Let your doctor know if you are experiencing unusual tiredness, weight gain, hair loss, unusually dry skin, mood changes, and intolerance to cold temperatures.
Tumour lysis syndrome: Imatinib, like many other cancer medications, causes many cancer cells to be suddenly killed when treatment is first started. This can overwhelm the body with waste products from the cells. As a result, the body may not be able to keep up with getting rid of all the waste. When this happens, you may experience nausea and shortness of breath, and notice cloudy urine or joint pain. This is called tumour lysis syndrome. Your doctor may prescribe some medications to help your body get rid of the waste products. Make sure you understand how to use these medications and report any of these signs or symptoms to your doctor immediately.
Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately. Women of childbearing age who are taking imatinib should use an effective method of birth control during treatment.
Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking imatinib, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
Children: The safety and effectiveness of using this medication have not been established for children less than 2 years of age. Growth may be slowed in children and adolescents that take this medication.
Seniors: Seniors have a greater risk of fluid retention than younger patients. Contact your doctor if you experience a sudden increase in weight or swelling of the ankles, lower legs, or hands. Your doctor will weigh and monitor you closely.
What other drugs could interact with this medication?
There may be an interaction between imatinib and any of the following:
- alpha blockers (e.g., alfuzosin, doxazosin, silodosin, tamsulosin)
- amphotericin B
- anticancer medications (e.g., cabazitaxel, docetaxel, doxorubicin, etoposide, ifosfamide, irinotecan, vincristine)
- "azole" antifungal medications (e.g., fluconazole, itraconazole, ketoconazole)
- beta-blockers (e.g., atenolol, propranolol, metoprolol)
- bacillus Calmette-Guerin (BCG)
- barbiturates (e.g., butalbital, pentobarbital, phenobarbital)
- benzodiazepines (e.g., chlordiazepoxide, clonazepam, diazepam, lorazepam)
- calcium channel blockers (e.g., nifedipine, diltiazem, verapamil, amlodipine, felodipine)
- corticosteroids (e.g., dexamethasone, prednisone, methylprednisolone)
- estrogens (e.g., conjugated estrogen, estradiol, ethinyl estradiol)
- "gliptin" diabetes medications (e.g., linagliptin, saxagliptin, sitagliptin)
- grapefruit juice
- HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delaviridine, efavirenz, etravirine, nevirapine)
- HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
- macrolide antibiotics (e.g., azithromycin, clarithromycin, erythromycin)
- nitrates (e.g., isosorbide dinitrate, isosorbide mononitrate)
- peginterferon alfa-2b
- progestins (e.g., dienogest, levonorgestrel, medroxyprogesterone, norethindrone)
- proton pump inhibitors (PPIs; e.g., esomeprazole, lansoprazole, omeprazole, pantoprazole, rabeprazole)
- St. John's wort
- selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, duloxetine, fluoxetine, paroxetine, sertraline)
- "statin" anticholesterol medications (e.g., atorvastatin, lovastatin, simvastatin)
- tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, trimipramine)
- other tyrosine kinase inhibitors (e.g., dasatinib, imatinib, nilotinib, sunitinib)
If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:
- stop taking one of the medications,
- change one of the medications to another,
- change how you are taking one or both of the medications, or
- leave everything as is.
An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.
Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.