Busulfan is a chemotherapy drug. It is most often used to treat chronic myeloid leukaemia (CML), but may sometimes be used before a stem cell transplant for other types of cancer and leukaemia. This information describes busulfan, 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 cancer or leukaemia, which give more 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.

Busulfan is available as 2mg white tablets, and as a colourless liquid after being dissolved from a white powder.

Busulfan is given:

• As tablets swallowed whole.

• As a drip (infusion) through a fine tube (cannula) inserted into a vein. It may be given through a central line, which is inserted under the skin into a vein near the collarbone, or through a PICC line, which is inserted into a vein in the crook of your arm when used as a high-dose treatment. The infusion usually takes about two hours.

Chemotherapy is usually given as a course of several sessions (or cycles) of treatment over a few months. The length of your treatment and the number of cycles you have will depend on the type of cancer for which you are being treated.

Busulfan is sometimes given alongside other chemotherapy as part of a combination treatment (regimen). Your nurse or doctor will discuss your treatment plan with you.

Each person's reaction to chemotherapy is different. Some people have very few side effects, while others may experience more. The side effects described here will not affect everyone who is given busulfan, 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 that you can be aware of them if they occur. However, we have not included those that are very rare and therefore extremely unlikely to affect you. If you do notice any effects which you think may be due to the drug but which are not listed in this information, please discuss them with your doctor or chemotherapy nurse.

Lowered resistance to infection Busulfan can reduce the production of white blood cells by the bone marrow, making you more prone to infection. This effect can occur between 10–30 days after treatment has been given. Your blood cells will then increase steadily, and will usually return to normal levels over several weeks.

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 Busulfan 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 busulfan you may become anaemic. This may make you feel tired and breathless. You may need to have a transfusion of blood if the number of red blood cells becomes too low.

Skin changes Your skin may darken due to excess production of pigment in some areas.

Tiredness and feeling weak You may feel very tired. It is important to allow yourself plenty of time to rest.

Raised levels of uric acid in the blood A drug called allopurinol may be given to stop this happening. Allopurinol is taken as tablets. It may also help to drink plenty of fluids. While you are taking busulfan your uric acid levels may be checked regularly by blood tests.

Changes to the lungs Busulfan may cause some changes to the lungs. Tell your doctor if you smoke and if you notice any coughing or breathlessness. You may have a chest x-ray to check your lungs before you are given any busulfan.

Irritation of the bladder It is important to drink plenty of fluids to prevent the irritation. If you are having high-dose busulfan treatment you may sometimes be given fluids through a drip to help protect the bladder. If you notice any blood in your urine tell your doctor or nurse.

Skin changes Busulfan can cause a rash, which may be itchy. Your doctor can prescribe medicine to help with this.

Hair loss Hair loss does not usually occur if you take busulfan as tablets. It can occur if busulfan is taken as a high-dose intravenous treatment. The hair loss is temporary and your hair will return to normal once the treatment ends.

Your liver may be temporarily affected Busulfan may cause changes in the way that your liver works, but your liver will return to normal when the treatment is finished. This is unlikely to cause any symptoms or harm you, but your doctor will monitor this carefully. Samples of your blood will be taken from time to time to check how well your liver is working.

Feeling sick (nausea) and being sick (vomiting) This is a rare side effect unless you are having high does of busulfan through a vein. If you do feel sick this may begin a few hours after the treatment is given and last for up to five days. 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.

Sore mouth and ulcers Your mouth may become sore or you may notice small ulcers during this treatment. Drinking plenty of fluids, and cleaning your teeth regularly and gently with a soft toothbrush, can help to reduce the risk of this happening. Tell your nurse or doctor if you have any of these problems, as they can prescribe special mouthwashes and medicines, which prevent or clear any mouth infection.

Taste changes You may notice that your food tastes different. Normal taste will usually come back after the treatment finishes.

Diarrhoea This can usually be easily controlled with medicine, but let your doctor know if it is severe or if it continues. It is important to drink plenty of fluids if you have diarrhoea.

Loss of appetite A dietitian or specialist nurse at your hospital can give advice about how to boost your appetite, cope with eating difficulties and maintain your weight.

Dizziness, blurred vision or confusion These side effects are very rare and occur only with high-dose treatment. If you notice any of these effects tell your doctor immediately.

Second cancer With long-term use of this drug over many years, there is a very small risk of developing a second cancer. Your doctor or nurse will discuss this risk with you.

Cataracts (clouding of the eye's lens) Rarely these can occur some years after busulfan treatment. Let your doctor know if you notice any change in your eyesight.

Swelling and tenderness of the breasts This may be experienced by both men and women.

Fever and chills These may occur soon after the drug is given, but they do not usually last long. Your doctor may prescribe medicines to reduce this effect.

Fits or seizures When high doses of busulfan are given there is a small risk of seizures. Your doctor can discuss this with you and you may need to take medication to help prevent them.

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

Contraception It is not advisable to become pregnant or father a child while taking busulfan, 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.

• It is important to take your tablets at the right times. You must take them as directed by your doctor.
• Keep the tablets in the original packaging and store them at room temperature, away from heat and direct sunlight.
• Keep the tablets in a safe place where children cannot reach them, as busulfan could harm them.
• If your doctor decides to stop the treatment, return any remaining tablets to the pharmacist. Do not flush them down the toilet or throw them away.
• If you are sick just after taking the tablets let your doctor know as you may need to take another dose. Do not take another tablet without first telling your doctor.
• If you forget to take a tablet do not take a double dose. Inform your doctor and keep to your regular dose schedule.

This section is based on our Busulfan 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.
• The Medicines.org.uk website - www.medicines.org.uk (November 2007).
• British National Formulary (54th edition). British Medical Association and Royal Pharmaceutical Society of Great Britain, September 2007.
• The Chemotherapy Source Book (3rd edition). Ed. Perry. Lippincott, Williams and Wilkins, 2001.

For further references, please see general bibliography.