Cladribine is a chemotherapy drug that is given mainly as a treatment for hairy cell leukaemia and (more rarely) chronic lymphocytic leukaemia. This information describes cladribine, how it is given and some of its possible side effects. It should ideally be read with our general information about chemotherapy, and about your type of leukaemia, which give further information and advice.

If you have any further questions you can ask your doctor or nurse at the hospital where you are having your treatment, or speak to one of our cancer support service nurses.

Cladribine is a colourless liquid after being dissolved from powder.

It is given as a drip (infusion) through a fine tube (cannula) that is inserted into a vein. Some people have their chemotherapy given through a fine plastic tube that is inserted under the skin into a vein near the collarbone (central line) or passed through a vein in their arm (PICC line). Your doctor or nurse will explain more about this to you.

When used to treat hairy cell leukaemia, cladribine is given as a continuous infusion for seven days. This might involve a short stay in hospital. Some people may have the treatment given through a small portable pump attached to a central or PICC line, so that they can have some of the treatment at home.

There are several different types of pump, but all are small enough to be carried on a belt or in a holster. Before you go home you should be given instructions on how to look after the pump. Your nurse should explain how to care for it and what to do if something goes wrong.

When the infusion is finished there may be some fluid left in the pump. This may be normal as some types of pump need to be overfilled to get the correct dose. You can check with your nurse or pharmacist whether you have this type of pump.

If cladribine is being used to treat chronic lymphocytic leukaemia it is given by drip (infusion) for two hours each day, for five days. Each five-day course of treatment is known as a cycle. After the treatment, you will have a few weeks of rest before the next cycle is given. More than one cycle of treatment may be given.

Each person's reaction to chemotherapy is different. Some people have very few side effects, while others may experience more. The side effects described in this information will not affect everyone who is given cladribine, and may be different if you are having more than one chemotherapy drug.

We have outlined the most common side effects and some of the less common ones, so you can be aware of them if they occur. However, we have not included those which are very rare and therefore extremely unlikely to affect you. If you do notice any effects that you think may be due to the drug, but are not listed in this information, please discuss these with your doctor or chemotherapy nurse.

Lowered resistance to infection Cladribine can reduce the production of white blood cells by the bone marrow, making you more prone to infection. This effect can begin seven days after treatment has been given, and your resistance to infection usually reaches its lowest point 10–14 days after chemotherapy. Your blood cells will then increase steadily, and will usually have returned to normal within 21–28 days.

Contact your doctor or the hospital straightaway if:

• your temperature goes above 38ºC (100.5ºF)
• you suddenly feel unwell (even with a normal temperature).

You will have a blood test before having more chemotherapy to make sure that your cells have recovered. Occasionally it may be necessary to delay your treatment if the number of blood cells (the blood count) is still low.

Bruising or bleeding Cladribine can reduce the production of platelets (which help the blood to clot). Let your doctor know if you have any unexplained bruising or bleeding, such as nosebleeds, blood spots or rashes on the skin, or bleeding gums.

Anaemia (low number of red blood cells) While having treatment with cladribine you may become anaemic. This may make you feel tired and breathless. Let your doctor or nurse know if you develop these symptoms.

Feeling sick (nausea) and being sick (vomiting) If you do feel sick this may begin a few hours after the treatment is given and last for a few days. It is usually mild, and your doctor can prescribe very effective anti-sickness (anti-emetic) drugs to prevent, or greatly reduce, nausea and vomiting. If the sickness is not controlled, or continues, tell your doctor; they can prescribe other anti-sickness drugs which may be more effective. Some anti-sickness drugs can cause constipation. Let your doctor or nurse know if this is a problem.

Skin rash A skin rash can sometimes occur while you are having the treatment or afterwards. It is important to let your doctor know if this happens.

Fatigue Fatigue can be a problem for the time that you are having the treatment. It is important to ensure that you rest and take things at your own pace.

Your liver and kidneys may be affected Cladribine may cause changes in the way that your liver and kidneys work. This is unlikely to cause you any harm, but your doctor will monitor this carefully. Samples of your blood will be taken from time to time to check how well your liver and kidneys are working (kidney function). If your kidney function is lower than normal for your age the dose of cladribine will be reduced.

Raised levels of uric acid in the blood Raised levels of uric acid can affect the kidneys. A drug called allopurinol may be given to protect the kidneys. It may also help to drink plenty of fluids. While you are taking cladribine your uric acid levels will be checked regularly by blood tests.

Problems with neurological function This is rare and is due to the effects of cladribine on the nervous system. If you notice a loss of sensation in your arms or legs, or feel confused or sleepy, it is important to let your doctor know straight away.

Fever and chills These may occur from the time that the drug is given, but they do not usually last long. Your doctor may prescribe medicines such as paracetamol to reduce this side effect.

Risk of blood clots Cancer can increase your risk of developing a blood clot (thrombosis), and having chemotherapy may increase this risk further. A blood clot may cause symptoms such as pain, redness and swelling in a leg, or breathlessness and chest pain. Blood clots can be very serious so it is important to tell your doctor straightaway if you have any of these symptoms. However, most clots can usually be successfully treated with drugs to thin the blood. Your doctor or nurse can give you more information.

Other medicines Some other medicines can be harmful to take when you are having chemotherapy. Let your doctor know about any medications you are taking, including non-prescribed drugs such as complementary therapies and herbal drugs.

Fertility Your ability to conceive or father a child may be affected by taking this drug. It is important to discuss fertility with your doctor before starting this treatment.

Contraception It is not advisable to become pregnant or father a child while taking cladribine, as the developing foetus may be harmed. It is necessary to use effective contraception while taking this drug, and for at least a few months afterwards. Again, discuss this with your doctor.

Discomfort at injection site Let your doctor or nurse know if, during or after the infusion, you have any discomfort or change in sensation in the area of the injection.

This section is based on our Cladribine factsheet which has been compiled using information from a number of reliable sources, including:

• Martindale: The Complete Drug Reference (35th edition). Eds. Sweetman et al. Pharmaceutical Press, 2007.
• British National Formulary (54th edition). British Medical Association and Royal Pharmaceutical Society of Great Britain, September 2007.
• The Medicines.org.uk website - www.medicines.org.uk (November 2007).
• The Chemotherapy Source Book (3rd edition). Ed. Perry. Lippincott, Williams and Wilkins, 2001.

For further references, please see general bibliography.