Before taking mercaptopurine

Before taking mercaptopurine make sure your doctor or pharmacist knows:

• If you are pregnant, trying for a baby or breast-feeding.
• If you know you have an inherited deficiency of an enzyme called thiopurine methyltransferase (TPMT).
• If you have liver or kidney problems.
• If you are taking other medicines, including those available to buy without a prescription, herbal or complementary medicines. It is particularly important that your doctor knows if you are taking allopurinol.
• If you have ever had an allergic reaction to this or to any other medicine.

How to take mercaptopurine

• Mercaptopurine is prescribed by a hospital specialist.
• Your dose will be worked out according to your weight.
• Before beginning your treatment, read the manufacturer's printed information leaflet.
• Take mercaptopurine exactly as you have been directed. Swallow the tablets with a drink of water.
• If you forget to take a dose and you do not remember until the next day, leave out the missed dose. Do not take two doses together to make up for a forgotten dose.

Getting the most from your treatment

• It is important that you do not become pregnant while you are taking mercaptopurine. If this affects you, ask your doctor for advice and make sure you use effective contraception.
• While you are taking mercaptopurine do not have any immunisations (vaccinations) without talking to your doctor first. Mercaptopurine lowers your body's resistance and there is a chance that you may get an infection from some vaccines.
• Keep your regular doctor's appointments and appointments for blood tests so your progress can be monitored.
• If you are having any treatment like an operation or dental treatment, tell the person carrying out the treatment that you are taking mercaptopurine.
• If you buy any medicines, check with a pharmacist that they are safe to take with mercaptopurine.
• Any unwanted tablets must be disposed of in a special way - ask your local pharmacy for advice.

Can mercaptopurine cause problems ?

Mercaptopurine can lower the number of white cells in your blood, increasing the chance of you getting an infection. You should take certain precautions to reduce the risk of infection - if possible, avoid people with infections and let your doctor know if you think you are getting a sore throat or if you have a high temperature.

Your doctor will have discussed with you the possibility of unwanted side-effects of treatment with mercaptopurine. Let your doctor know if you experience any of the following or any other symptoms which you think may be due to this medicine:

How to store mercaptopurine

• Keep all medicines out of the reach and sight of children.
• Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

References

• Manufacturer's PIL, Puri-Nethol® Tablets, Aspen Europe GmbH, electronic Medicines Compendium. Dated September 2008, accessed September 2010.
• British National Formulary; 60th Edition (September 2010) British Medical Association and Royal Pharmaceutical Society of Great Britain, London (link to current BNF)