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 Philadelphia chromosome positive chronic myeloid leukemia (Ph+ CML) in chronic phase. It works by affecting enzymes that play a role in certain cancer cells.

It is also used to treat adults with Ph+ CML in blast crisis (sudden attack), accelerated phase (fast growth), or chronic phase (long-term illness) after the failure of interferon-alpha therapy.

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 be used to treat certain types of gastrointestinal stromal tumours (GIST), a cancer of the stomach and bowels. 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.

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.

The dose of imatinib varies depending on the condition being treated. Your doctor will tell you how many tablets to take per day and how often to take them.

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 taking the 400 mg tablet and it is too large to swallow, you may break it into 2 pieces and swallow each piece with a glass of water. Alternatively, 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. If you vomit after taking a dose, do not take a replacement dose. Take your next dose at the usual time.

Store this medication at room temperature, in its original package, protect it from light and moisture, and keep it out of the reach of children.

100 mg
Each dark yellow to brownish orange, round, biconvex, film-coated tablet, debossed with "FG" and "1" on either side of breakline on one side and plain on the other side, contains 100 mg of imatinib (as mesylate beta crystals). Nonmedicinal ingredients:  colloidal anhydrous silica, crospovidone, hypromellose, iron oxide red, iron oxide yellow, magnesium stearate, microcrystalline cellulose, polyethylene glycol, and talc.

400 mg
Each dark yellow to brownish orange, oval, biconvex, film-coated tablet, debossed with "FG" and "2" on either side of breakline on one side and plain on the other side, contains 400 mg of imatinib (as mesylate beta crystals). Nonmedicinal ingredients: colloidal anhydrous silica, crospovidone, hypromellose, iron oxide red, iron oxide yellow, magnesium stearate, microcrystalline cellulose, polyethylene glycol, and talc.

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.

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
• constipation
• cough
• diarrhea
• difficulty sleeping
• dizziness
• dry mouth
• fatigue
• gas (flatulence)
• headache
• increased muscle tension
• increased skin sensitivity to the sun
• increased tear production
• indigestion or heartburn
• itchy, dry skin
• itchy, dry eyes
• joint pain
• joint swelling
• loss of appetite
• mouth sores
• muscle pain
• muscle spasms and cramps
• nausea
• night sweats
• numbness or tingling of the hands of feet
• skin rash
• slowed growth (children and adolescents)
• taste disturbance
• unusual hair loss or thinning
• vomiting
• weakness
• 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
• cellulitis (red, hot, painful, swollen areas under the skin)
• changed or unusual menstrual bleeding
• difficult or painful breathing
• eye infection
• fainting
• fever
• hearing problems
• numb or cold toes and fingers
• pain or difficulty walking
• red or swollen palms of the hands or soles of the feet
• 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 inflammatory bowel disease (e.g., nausea, vomiting, diarrhea, stomach pain, fever)
• 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
• swelling around the eyes or eyelids
• symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
• symptoms of lung problems (e.g., cough, difficult or painful breathing)
• vision changes

Stop taking the medication and seek immediate medical attention if any of the following occur:

• chest pain
• irregular or pounding heartbeat
• seizures
• 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 a serious allergic reaction (e.g., abdominal cramps, swelling of lips, hives, difficulty breathing, nausea, vomiting, swelling face and throat)
• 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 build-up in the abdomen (e.g., shortness of breath, feeling full, abdominal pain)
• 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.

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.

Hepatitis B: People who have hepatitis B or have had hepatitis B infection are at risk of the infection returning when they are taking imatinib or after stopping the medication. If you have a history of hepatitis B infection, 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.

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: Decreased kidney function or kidney disease may cause this medication to build up in the body, causing side effects. 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.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Male fertility: There is evidence that men who take imatinib may experience decreased fertility. If this is a concern, speak to your doctor about fertility preservation.

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.

Rarely, imatinib can cause perforation (holes) in the stomach or intestines. If you experience severe abdominal pain, fever, vomiting, or black and tarry stools, contact your doctor immediately.

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 breast-feeding 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. Children and adolescents who take this medication may experience slowed growth.

Seniors: Seniors have a greater risk of fluid retention than younger people taking this medication. 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.

There may be an interaction between imatinib and any of the following:

• acetaminophen
• alpha-blockers (e.g., alfuzosin, doxazosin, silodosin, tamsulosin)
• amiodarone
• anticancer medications (e.g., cabazitaxel, docetaxel, doxorubicin, etoposide, ifosfamide, irinotecan, vincristine)
• antipsychotics (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• apixaban
• aprepitant
• "azole" antifungal medications (e.g., fluconazole, itraconazole, ketoconazole)
• beta-blockers (e.g., atenolol, propranolol, metoprolol)
• bacillus Calmette-Guerin (BCG)
• baricitinib
• benzodiazepines (e.g., chlordiazepoxide, alprazolam, clonazepam, diazepam, lorazepam, triazolam)
• bosentan
• bromocriptine
• buprenorphine
• buspirone
• calcium channel blockers (e.g., nifedipine, diltiazem, verapamil, amlodipine, felodipine)
• cannabis
• clindamycin
• cobicistat
• colchicine
• conivaptan
• corticosteroids (e.g., budesonide, dexamethasone, fluticasone, prednisone, methylprednisolone)
• cyclosporine
• darifenacin
• denosumab
• disopyramide
• domperidone
• dronedarone
• echinacea
• elbasvir and grazoprevir
• eletriptan
• elexacaftor, tezacaftor, and ivacaftor
• eliglustat
• enzalutamide
• eplerenone
• ergot alkaloids (e.g., ergotamine, dihydroergotamine)
• flibanserin
• gemfibrozil
• grapefruit juice
• guanfacine
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., efavirenz, etravirine, nevirapine, rilpivirine)
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• ibuprofen
• ivabradine
• lansoprazole
• leflunomide
• lemborexant
• levothyroxine
• lidocaine
• lomitapide
• lumacaftor and ivacaftor
• macrolide antibiotics (e.g., azithromycin, clarithromycin, erythromycin)
• maraviroc
• mesalamine
• methadone
• mifepristone
• modafinil
• naloxegol
• narcotic analgesics (e.g., codeine, fentanyl, oxycodone)
• natalizumab
• ocrelizumab
• ofatumumab
• olsalazine
• phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• pimecrolimus
• praziquantel
• quinidine
• quinine
• rifabutin
• rifampin
• rivaroxaban
• roflumilast
• rupatadine
• St. John's wort
• salmeterol
• saxagliptin
• seizure medications (e.g., carbamazepine, clobazam, levetiracetam, phenobarbital, phenytoin, primidone, topiramate, valproic acid, zonisamide)
• serotonin antagonists (e.g., granisetron, ondansetron)
• sertraline
• sirolimus
• solifenacin
• sphingosine 1-phosphate receptor (S1P) receptor inhibitors (e.g., fingolimod, ponesimod, siponimod)
• "statin" anticholesterol medications (e.g., atorvastatin, lovastatin, simvastatin)
• sulfasalazine
• tacrolimus
• ticagrelor
• tocilizumab
• tolterodine
• tolvaptan
• trazodone
• tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, trimipramine)
• other tyrosine kinase inhibitors (e.g., ceritinib, dasatinib, imatinib, nilotinib, sunitinib)
• vaccines
• warfarin
• zopiclone

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.