Immunosuppressive drugs are drugs that suppress the immune system; they are usually used in the prevention of organ rejection in organ transplant recipients or to treat autoimmune diseases. There are five major classes of immunosuppressants: there are the calcineurin inhibitors (CNIs), the mammalian target of rapamycin (mTOR) inhibitors (TORIs), corticosteroids (CCSs), monoclonal antibodies (mAbs), antimetabolites (AMBs) and alkylating agents (AKAs). They work via distinct mechanisms, have unique clinical profiles and affect unique immune cell ines.
The major alkylating agent used in immunosuppression is cyclophosphamide which is a nitrogen mustard that forms cross-links with base pairs on DNA strands, triggering apoptosis in rapidly-proliferating cells but also some slowly-proliferating cells like lymphocytes. Causes neutropenia too (usually reaches a nadir 1-2 weeks after treatment and full recovery takes about 3-4 weeks); red blood cell and platelet counts are relatively unaffected, usually.
Antimetabolites work by inhibiting the formation of crucial metabolites required for cell division, protein synthesis or other important biological processes. The major ones used as immunosuppressants include:
- Azathioprine (used to prevent organ rejection and to treat several autoimmune diseases; specifically active against proliferating lymphocytes, it inhibits antibody responses and cellular immunity)
- Mercaptopurine, active metabolite of azathioprine; most commonly used to treat cancers, but also used to treat inflammatory bowel disease.
- Methotrexate (used to treat several autoimmune diseases)
- ↑ 1.0 1.1 Brunton, LL; Chabner, BA; Knollmann, BC, ed. (2010). "Chapter 61. Cytotoxic Agents". Goodman & Gilman's Pharmacological Basis of Therapeutics (12th ed.). New York, USA: McGraw-Hill Professional. ISBN 978-0-07-162442-8.
- ↑ Brayfield, A, ed. (7 January 2014). "Cyclophosphamide". Martindale: The Complete Drug Reference. London, UK: Pharmaceutical Press. Retrieved 20 November 2014.
- ↑ Rossi, S, ed. (July 2014). "Azathioprine". Australian Medicines Handbook. Adelaide, Australia: Australian Medicines Handbook Pty Ltd. Retrieved 20 November 2014.
- ↑ Rossi, S, ed. (July 2014). "Mercaptopurine". Australian Medicines Handbook. Adelaide, Australia: Australian Medicines Handbook Pty Ltd. Retrieved 20 November 2014.