In many rheumatic diseases, inflammation causes damage to parts of the body, such as what happens to the joints in rheumatoid arthritis. In many cases, inflammation results from autoimmunity, a malfunction of the immune system where one's own tissues or organs are not recognized as such and are attacked by the body's immune system. Chemotherapy slows cell reproduction and decreases certain products made by these cells, and therefore may help people with certain inflammatory and autoimmune diseases. Because of the suppressive effect of chemotherapy on autoimmunity, these drugs are sometimes called immunosuppressive drugs. Although there are many chemotherapy drugs, only three have widespread use in treating rheumatic diseases today.
Most patients can take methotrexate by mouth in a single, weekly dose.
Some patients prefer to take it as an injection once a week. Azathioprine Azathioprine has been used for many years as an immunosuppressive drug to prevent graft rejection in patients receiving kidney transplants. Usually taken in a single daily dose by mouth, it is also used to suppress the abnormal immune response in some patients with vasculitis, systemic lupus erythematosus, rheumatoid arthritis and vasculitis. Cyclophosphamide Cyclophosphamide is considerably more powerful and toxic than methotrexate and azathioprine. It is used to treat the most aggressive and dangerous rheumatic diseases, such as severe systemic lupus erythematosus and some forms of vasculitis.