Imatinib is a tyrosine kinase inhibitor (TKI). Tyrosine kinases are proteins in the body that control how cells grow and divide. Imatinib blocks (inhibits) signals in the cancer cells that make them grow and divide. Blocking the signals causes the cells to die.
Imatinib may be used to treat:
- chronic myeloid leukaemia (CML), a cancer of white blood cells
- a type of acute lymphoblastic leukaemia (ALL) called Philadelphia chromosome positive (Ph+ALL)
- blood disorders where some blood cells grow out of control (myelodysplastic and myeloproliferative conditions)
- blood disorders where blood cells called eosinophils grow out of control (advanced hypereosinophilic syndrome and chronic eosinophilic leukaemia).
It may also be used to treat:
- gastro-intestinal stromal tumours (GISTs), a rare type of cancer that affects the supporting tissue of the bowel or stomach
- dermatofibrosarcoma protuberans (DFSP), a rare type of cancer that affects the tissue under the skin
- other types of cancers as part of a clinical trial.
Imatinib is usually available for CML and GIST. For other conditions and cancers, it may only be available in some situations. Your cancer doctor can tell you if it is suitable for you. Some people may be given it as part of a clinical trial. If a drug is not available on the NHS, there may be different ways you are still able to have it. Your cancer doctor can give you advice.
Taking imatinib tablets
You normally take imatinib once a day. People taking a higher dose (800mg a day) usually take this in two doses of 400mg. You should take the tablets with a meal and a large glass of water.
If you find it hard to swallow the tablets, tell your doctor. They may suggest that you dissolve them in still water or apple juice. The liquid should be about 50ml for a 100mg tablet and 200ml for a 400mg tablet. Stir the liquid with a spoon until the tablets are completely dissolved and drink it immediately. Wash the glass and spoon straight away.
If you are sick just after taking the tablets, contact the hospital. You may need to take another dose.
If you forget to take a tablet, take it as soon as you remember, unless it is nearly time for your next dose. It is important that you do not take a double dose. Keep to your regular schedule and tell your doctor or nurse.
Here are some other things to remember about your tablets:
- Keep them in the original package and at room temperature, away from heat and direct sunlight.
- Keep them safe and out of the reach of children.
- If your treatment is stopped, return any remaining tablets to the pharmacist.
We explain the most common side effects of this treatment here. We also include some less common side effects. You may get some of the side effects we mention, but you are unlikely to get all of them.
If you are also having treatment with other cancer drugs, you may have some side effects that we have not listed here. Always tell your doctor, nurse or pharmacist about any side effects you have.
Your doctor can give you drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist explains. This means they will be more likely to work for you. Your nurse will give you advice about managing your side effects. After your treatment is over, most side effects start to improve.
Serious and life-threatening side effects
Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.
Contact the hospital
Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.
We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.
Risk of infection
This treatment can reduce the number of white blood cells in your blood. These cells fight infection. If the number of white blood cells is low, you are more likely to get an infection. A low white blood cell count is called neutropenia.
If you have an infection, it is important to treat it as soon as possible. Contact the hospital straight away on the 24-hour contact number you have if:
- your temperature goes over 37.5°C (99.5°F)
- you suddenly feel unwell, even with a normal temperature
- you have symptoms of an infection.
Symptoms of an infection include:
- feeling shaky
- a sore throat
- a cough
- needing to pass urine a lot.
It is important to follow any specific advice your cancer treatment team gives you.
The number of white blood cells will usually return to normal before your next treatment. You will have a blood test before having more treatment. If your white blood cell count is low, your doctor may delay your treatment for a short time.
Bruising and bleeding
This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot. Tell your doctor or nurse if you have any bruising or bleeding that you can’t explain. This includes:
- bleeding gums
- tiny red or purple spots on the skin that may look like a rash.
Anaemia (low number of red blood cells)
This treatment can reduce the number of red blood cells in your blood. These cells carry oxygen around the body. If the number of red blood cells is low, you may be tired and breathless. Tell your doctor or nurse if you feel like this.
If you are very anaemic, you may need a drip to give you extra blood cells. This is called a blood transfusion.
This is usually mild. Your doctor can prescribe anti-sickness (anti-emetic) drugs to prevent or reduce sickness and vomiting. Taking imatinib with food also helps. Tell your doctor if the sickness isn't controlled or if it continues. They can give you other anti-sickness drugs that may work better for you.
If you have diarrhoea, contact the hospital for advice. Try to drink at least 2 litres (3½ pints) of fluids every day. It can help to avoid alcohol, caffeine, milk products, high-fat foods and high-fibre foods.
This treatment may cause headaches. If this happens, tell your doctor or nurse. They can give you painkillers.
Leg aches or cramps
If you are worried about these, tell your doctor. They can give you drugs to make you more comfortable.
Build-up of fluid
This is fairly common. It is not usually harmful, but can be upsetting. Many people gain weight or develop swelling around the eyes and ankles because of fluid build-up. Drugs that make you pass more urine (diuretics) can help get rid of some fluid, but it often settles down by itself. If you put on a lot of weight quickly, let your doctor know.
Effects on the eyes
Imatinib can cause eye pain, dry or watery eyes, or changes in vision. If your eyes are affected, tell your doctor. You should be careful when driving or operating machinery if your vision has changed.
This treatment may affect your skin. It can cause a rash, which may be itchy. Your doctor or nurse can tell you what to expect. If your skin feels dry, try using an unperfumed moisturising cream every day.
Always tell your doctor or nurse about any skin changes or if they get worse. They can give you advice and may prescribe creams or medicines to help. Any changes to your skin are usually temporary and improve when treatment finishes.
Changes to your taste or loss of appetite
You may notice changes to your taste or lose your appetite while you are having imatinib. This can be mild and may only last a few days. If it doesn’t improve, you can ask to see a dietitian or specialist nurse at your hospital. They can give you advice on improving your appetite and coping with taste changes.
Some people have indigestion or acid reflux (acid comes up from the stomach into the gullet) when taking this treatment. Tell your doctor if you are affected as they can prescribe treatment to help.
This treatment can cause sleeplessness (insomnia) in some people. If you are finding it difficult to sleep, talk to your doctor or specialist nurse.
Breathlessness and a cough
You may feel more out of breath than normal or develop a cough. Let your doctor know if you notice this.
Effects on the liver
Imatinib may cause changes in the way that your liver works. Your doctor will take blood samples to check your liver is working properly.
If you have had Hepatitis B (a liver infection) in the past, imatinib can make it active again. Your doctor or nurse will talk to you about this and test you for Hepatitis B. It is important to let your doctor know straight away if you feel unwell or have any severe side effects, even if they are not mentioned above.
Some medicines can be harmful when you are taking imatinib. This includes medicines you can buy in a shop or chemist. They may make imatinib less effective or increase the side effects it can cause. Tell your doctor and check with your pharmacist about any medicines you are taking, including over-the-counter drugs such as paracetamol, complementary therapies and herbal drugs.
People taking thyroid treatment
If you have had your thyroid removed and are taking levothyroxine, talk to your doctor. Imatinib can affect how levothyroxine works.
Effects on the heart
If you have heart problems, these may be made worse by imatinib. Your doctor will monitor you during your treatment to check for any problems. If you have chest pains or any worsening symptoms, speak to your doctor immediately.
Women are advised not to become pregnant during their treatment. This is because imatinib may harm a developing baby. It is important to use contraception during treatment and for several months afterwards. You can talk to your doctor or nurse about this.
Women are advised not to breastfeed during treatment and for a few months afterwards. This is in case there is any imatinib in their breast milk.
Some brands of imatinib contain a small amount of lactose. If you have a lactose intolerance, talk to your doctor before you start taking this.
If you need to go into hospital for any reason, always tell the doctors and nurses that you are having treatment with imatinib. You shouldn’t stop or restart imatinib without advice from your cancer doctor. Tell the doctors and nurses the name of your cancer doctor so they can ask them for advice.