Mercaptopurine (6-MP), sold under the brand name Purinethol among others, is a medication used for cancer and autoimmune diseases. Specifically it is used to treat acute lymphocytic leukemia (ALL), chronic myeloid leukemia (CML), Crohn's disease, and ulcerative colitis. For ALL it is generally used with methotrexate. It is taken by mouth.
Common side effects include bone marrow suppression, liver toxicity, vomiting, and loss of appetite. Other serious side effects include an increased risk of future cancer and pancreatitis. Those with a genetic deficiency in thiopurine S-methyltransferase are at higher risk of side effects. Use in pregnancy may harm the baby. Mercaptopurine is in the thiopurine and antimetabolite family of medications.
Mercaptopurine was approved for medical use in the United States in 1953. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. The wholesale cost in the developing world is about 18.42 to 200.16 USD a month. In the United Kingdom this costs the NHS about 121.13 pounds per month. In the United States the wholesale cost is about 99.16 USD per month as of 2016.