By mouth, once daily. The dosage is based upon your body weight and is started usually at a dose of 1mg/kg each day and may be increased to 1.5mg/kg daily.
A small number of patients may experience side effects that will prevent them from continuing with treatment. Should you develop symptoms that might be related to your treatment please let me know.
Side effects that you should look out for include:
Nausea / vomiting and loss of appetite (<20% and often during second week of treatment)
Abdominal pain – should this develop, the drug should be stopped immediately. There may be inflammation in the pancreas gland; this is rare however.
Adverse effects on the blood so that the bone marrow does not make enough blood cells (1-2%)
Fever, weakness and fatigue (rare)
Unusual bleeding / bruising (rare)
Inflammation in the liver or jaundice (rare; <1%)
There is some evidence to suggest that the risk of lymphoma may be increased slightly. In addition, some forms of skin cancer are more common whilst taking mercaptopurine. It is sensible to use sunscreens and or protective clothing to reduce sunlight exposure.
Usually 6-12 weeks.
Yes, there is no known interaction with alcohol.
Mercaptopurine is safe to take in pregnancy. These is no evidence that it increases the risk of miscarriage or low birth weight above that associated with inflammatory bowel disease per se.
Women receiving mercaptopurine ideally should avoid breast feeding.
Keep all medicines out of the reach of children. Never give any medication prescribed for you to anyone else. It may harm them even if their symptoms are the same as yours.
Whilst taking this treatment, you will need regular blood tests to monitor blood cell counts and liver function. Once the dose of treatment is stable, the frequency of blood testing will be reduced. The testing will be performed at your GP surgery, your GP and I will be responsible for keeping an eye on the blood test results.
For the first 8 weeks of treatment a blood test (full blood count and liver function test) will need to be performed every week and if these are satisfactory, then every 12 weeks thereafter.
Immunisation with LIVE vaccines should be avoided (Influenza and pneumovax can be given). Please discuss with your GP if necessary.
Other medicines that you are prescribed may interact with mercaptopurine such as allopurinol (for gout), warfarin (for blood thinning) and certain antibiotics (co-trimoxazole and trimethoprim). You should discuss these with your GP.