• Keep this leaflet. You may need to read it again.
• If you have any further questions, ask your doctor, pharmacist or nurse.
• This medicine has been prescribed for you only. Do not pass it on to others. It may harm them, even if their signs of illness are the same as yours.
• If you get any side effects talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. See section 4.

1 What Mercaptopurine is and what it is used for
2 What you need to know before you take Mercaptopurine
3 How to take Mercaptopurine
4 Possible side effects
5 How to store Mercaptopurine
6 Contents of the pack and other information

If you are allergic to 6-mercaptopurine or any of the other ingredients of this medicine (see section 6).

Do not get vaccinated with yellow fever vaccine whilst you are taking 6-mercaptopurine because it may be fatal.

Talk to your doctor or pharmacist or nurse before taking Mercaptopurine if:

• you have recently received, or are due to receive, a vaccination (vaccine). If you have been vaccinated with yellow fever vaccine
• you take Mercaptopurine, you should not have a live organism vaccine (for example; flu vaccine, measles vaccine, BCG vaccine, etc.) until advised it is safe to do so by your doctor. This is because some vaccines may give you an infection if you receive them while you are taking Mercaptopurine
• you have kidney or liver problems, as your doctor will need to check that they are working properly
• you have a condition where your body produces too little of the enzyme called TPMT (thiopurine methyltransferase) as your doctor may need to adjust the dose
• you are planning to have a baby. This applies to both men and women. 6-mercaptopurine may harm your sperm or eggs (see ‘Pregnancy, breast-feeding and fertility’ below)
• you have an inherited mutation in the NUDT15-gene (a gene which is involved in the break-down of Mercaptopurine in the body), you have a higher risk of infections and hair loss, and your doctor may in this case give you a lower dose
• you have an allergy to a medicine called azathioprine (also used to treat cancer)
• you have, or have not, had chicken pox, shingles or hepatitis B (a liver disease caused by a virus)
• you have a genetic condition called Lesch-Nyhan Syndrome

If you are receiving immunosuppressive therapy, taking Mercaptopurine could put you at greater risk of:

• Tumours, including skin cancer. Therefore, when taking Mercaptopurine, avoid excessive exposure to sunlight, wear protective clothing and use protective sunscreen with a high protection factor
• lymphoproliferative disorders:
  • Treatment with Mercaptopurine increases your risk of getting a type of cancer called lymphoproliferative disorder. With treatment regimen containing multiple immunosuppressants (including thiopurines), this may lead to death
  • A combination of multiple immunosuppressants, given concomitantly increases the risk of disorders of the lymph system due to a viral infection (Epstein-Barr virus (EBV) - associated lymphoproliferative disorders)

Taking Mercaptopurine could put you at greater risk of:

• developing a serious condition called Macrophage Activation Syndrome (excessive activation of white blood cells associated with inflammation), which usually occurs in people who have certain types of arthritis
• Some patients with inflammatory bowel disease who have received 6-mercaptopurine have developed a rare and aggressive type of cancer called Hepatosplenic T-cell Lymphoma (see section 4, Possible side effects)

The use of 6-mercaptopurine for the treatment of inflammatory bowel disease (IBD) is an unlicensed indication

Infections

When you are treated with Mercaptopurine the risk of viral, fungal and bacterial infections is increased and the infections may be more serious. See also section 4.

Tell your doctor before starting treatment whether or not you have had chickenpox, shingles or hepatitis B (a liver disease caused by a virus).

Blood tests

• Treatment with Mercaptopurine may affect your bone marrow. This means you may have a reduced number of white blood cells, platelets and (less commonly) red blood cells in your blood. Your doctor will carry out blood tests daily when you are at the beginning of your treatment (induction) and at least weekly when you are further along into your treatment (maintenance). This is in order to monitor the levels of these cells in your blood. If you stop treatment early enough, your blood cells will return to normal.

Liver function

• Mercaptopurine is toxic to your liver. Therefore, your doctor will carry out weekly liver function tests when you are taking Mercaptopurine. If you already have liver disease, or if you are taking other medications which may affect your liver, your doctor will carry out more frequent tests. If you notice the whites of your eyes or your skin turn yellow (jaundice) tell your doctor immediately as you may need to stop your treatment immediately.

Vitamin B3 deficiency (Pellagra)

Tell your doctor immediately if you have diarrhoea, localised pigmented rash (dermatitis) or deterioration of your memory, reasoning and thinking skills (dementia), as these symptoms may indicate a vitamin B3 deficiency. Your doctor will prescribe vitamin supplements (niacin/nicotinamide) to improve your condition.

Sun and UV light

While you are taking mercaptopurine, you are more sensitive to the sun and UV light. You must make sure you limit your exposure to sunlight and UV light, wear protective clothing and use a sun cream with a high sun protection factor (SPF).

Low blood sugar (sweating more than usual, nausea, dizziness, confusion, etc.) has sometimes been seen in children, mainly in children under the age of six or with a low body mass index. Talk to your child´s doctor if this happens.

If you are not sure if any of the above applies to you, talk to your doctor or pharmacist before taking Mercaptopurine.

Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines.

In particular, tell your doctor or pharmacist if you are taking any of the following:

• Ribavirin (used to treat viruses)
• Other cytotoxic medicines (chemotherapy – used to treat cancer)
• Allopurinol, thiopurinol, oxipurinol or febuxostat (used to treat gout)
• Olsalazine or mesalazine (used to treat a Crohn’s disease and bowel problem called ulcerative colitis)
• Sulfasalazine (used to treat rheumatoid arthritis or ulcerative colitis)
• Methotrexate (used to treat cancer, rheumatoid arthritis or skin disease (severe psoriasis))
• Infliximab (used to treat certain bowel diseases (Crohn’s disease and ulcerative colitis), rheumatoid arthritis, ankylosing spondylitis or skin disease (severe psoriasis)
• Warfarin or acenocoumarol (used to ‘thin’ the blood)
• Anti-epileptic medicines such as phenytoin, carbamazepine. Blood levels of anti-epileptic medicines may need to be monitored and doses adjusted if necessary

Having vaccines while you are taking Mercaptopurine

If you are going to have a vaccination speak to your doctor or nurse before you have it. If you take Mercaptopurine, you should not have a live vaccine (like polio, measles, mumps and rubella.) until advised it is safe to do so by your doctor. This is because some vaccines may give you an infection if you have them whilst you are taking Mercaptopurine.

You can take Mercaptopurine with food or on an empty stomach, but the choice of method should be consistent from day to day. You should take your medicine at least 1 hour before or 2 hours after having milk or dairy products.

Do not take mercaptopurine if you are planning to have a baby without first speaking to your doctor for advice. This applies to both men and women. Mercaptopurine may harm your sperm or eggs. Reliable contraception must be used to avoid pregnancy whilst you or your partner are taking mercaptopurine. Both men and women should continue to use effective contraception for at least 3 months after stopping treatment. If you are already pregnant, you must talk to your doctor before taking mercaptopurine. Mercaptopurine should not be handled by women who are or planning to be pregnant or breast-feeding. Do not breast-feed while taking Mercaptopurine. Ask your doctor, pharmacist or midwife for advice.

Taking mercaptopurine during pregnancy may cause severe, excessive itching without a rash. You may also experience nausea and loss of appetite at the same time, which may indicate a condition called cholestasis of pregnancy (a disease of the liver during pregnancy). Talk with your doctor immediately, as this condition can cause harm to your unborn child.

It is not expected that Mercaptopurine will affect your ability to drive or use machines, but no studies have been done to confirm this.

If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this medicine.

You can take Mercaptopurine with food or on an empty stomach, but the choice of method should be consistent from day to day. You should take your medicine at least 1 hour before or 2 hours after having milk or dairy products.

It is important to take Mercaptopurine in the evening to make the medicine more effective.

If you take more Mercaptopurine than you should, you may feel sick, vomit or have diarrhoea. Tell your doctor immediately or go to a hospital immediately straight away. Take the medicine pack with you.

Tell your doctor. Do not take a double dose to make up for a forgotten dose.

Do not stop taking your medicine unless your doctor tells you to or you may get a relapse of your condition

Low blood sugar levels (sweating more than usual, nausea, dizziness, confusion, etc.) have been reported in some children receiving Mercaptopurine, the frequency is not known; However, most of the children were under the age of six years old and had a low body weight.

If you get any side effects or if the side effects get worse, talk to your doctor, nurse or pharmacist. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the

By reporting side effects you can help provide more information on the safety of this medicine.

The active substance is 6-mercaptopurine. Each tablet contains 50mg of 6-mercaptopurine. The other ingredients are lactose, maize starch, modified maize starch, stearic acid and magnesium stearate.

Mercaptopurine tablets are a pale yellow colour and are marked with ‘PT / 50’. Your Mercaptopurine tablets are in bottles of 25 tablets.

Marketing Authorisation holder:

Manufacturer:

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To listen to or request a copy of this leaflet in Braille, large print or audio please call, free of charge:

0800 198 5000 (UK only)

Please be ready to give the following information:

Product name Mercaptopurine 50mg Tablets

Reference number: PL 39699/ 0047

This is a service provided by the Royal National Institute of Blind People.