Immunosuppressive drugs suppress actions of the immune system and its inflammatory response. These drugs are useful for very active IBD that does not respond to standard therapy and help maintain remission. An immunosuppressant is often combined with a steroid to speed up response during active disease. In some instances, an immunosuppressant drug may also be given along with an anti-TNF drug, such a infliximab or adalimumab, in order to further improve upon the short and long term effectiveness of these drugs.
The immunosuppressants used in IBD are azathioprine (Imuran), mercaptopurine (6-MP, Purinethol), methotrexate, and cyclosporine (Neoral, Sandimmune). Patients on immunosuppresive drugs require regular blood tests to monitor for potential adverse effects.
Azathioprine is a prodrug of 6-mercaptopurine. These agents are often used for maintenance therapy of Crohn's disease and for active disease that does not respond to steroids. It is also used for maintenance therapy in patients with ulcerative colitis who cannot take 5-ASA drugs because of side effects or for those patients in whom 5-ASA does not adequately maintain remission. Rare but serious side effects effects of azathioprine and 6-mercaptopurine include: pancreatitis, hepatitis, and bone marrow suppression.
Methotrexate is an effective alternative for patients with Crohn's disease who have failed other treatments and cannot tolerate other immunosuppressive drugs. Its use is limited by its uncommon but serious side effects such as liver damage and lung inflammation.
Cyclosporine, given intravenously, is occasionally used for treatement of severe active ulcerative colitis that is not responding to other therapies. Side effects occur commonly with cyclosporine and the beneficial effect of treatment is often not maintained when patients are switched to the oral form of the drug. Thus, it is not useful in long-term maintenance therapy.