Mercaptopurine (also called 6-Mercaptopurine, 6-MP or its brand name Purinethol) is an immunosuppressive drug used to treat leukemia. It is also used for pediatric non-Hodgkin's lymphoma, polycythemia vera, psoriatic arthritis, and inflammatory bowel disease (such as Crohn's Disease and ulcerative colitis). Mechanisms of Action Mercaptopurine inhibits purine nucleotide synthesis and metabolism. This alters the synthesis and function of RNA and DNA. Mercaptopurine interferes with nucleotide inte… (More on Mercaptopurine)