Chemotherapy drugs decrease the ability of rapidly growing cancer cells to reproduce and in some cases deprive them of nutrients needed to grow. Chemotherapy medication can also help treat rheumatoid arthritis, a specific type of autoimmune arthritis in which the immune system, which normally attacks invaders, attacks the body's own cells instead. Chemotherapy agents suppress the immune system, decreasing joint damage and slowing disease progression, MayoClinic.com explains.
Methotrexate
Methotrexate, sold as Rheumatrex or Trexall, is the first-line chemotherapy treatment for rheumatoid arthritis, according to the Johns Hopkins Arthritis Center. It falls under the category of a DMARD, or disease modifying anti-rheumatic drug. Methotrexate is given once a week in oral or injection form; it has anti-inflammatory effects at doses given for rheumatoid arthritis, the Merck Manual states. Methotrexate is often given in combination with other medications to increase efficacy. It can cause liver and kidney damage, bone marrow suppression and pneumonitis, a potentially fatal disease of the lungs. Lung disease affects up to 5 percent of those taking the drug, University of Maryland Medical Center reports. Around 20 percent of people taking methotrexate stop the drug due to lesser side effects such as nausea and vomiting, rash, hair loss, mouth sores and aching muscles.
Cyclophosphamide
Cyclophosphamide, sold as Cytoxan, is a strong immunosuppressant that decreases the immune system response that causes the symptoms of rheumatoid arthritis. It is used to treat severe cases of rheumatoid arthritis. Cytoxan is given orally or intravenously and can cause liver damage, premature ovarian failure, hemorrhagic cystitis, immune system suppression leading to increased risk of infection and possibly increase the risk of developing cancer, especially bladder cancer, Johns Hopkins Arthritis Center warns. Blood counts must be monitored to recognize serious problems early.
Azathioprine
Azathioprine, sold as Imuran, is like Cytoxan in that it has serious immunosuppressive side effects and is largely used to treat severe rheumatoid arthritis. Nausea and hair loss are common side effects, but liver damage, bone marrow suppression and increased risk of cancer development may also occur, Johns Hopkins Arthritis Center states.
Rituximab
Rituximab, sold as Rituxan, depletes B cells that can cause inflammatory reactions. Rituxan is used only for people who have had poor response from tumor necrosis factor, or TNF antagonist drugs, Johns Hopkins Arthritis Center says. Rituxan is initially administered intravenously in two doses given two weeks apart. Infusion reactions such as hives, fever, chills, changes in blood pressure and difficulty breathing can occur, most commonly with the first infusion. Other side effects include increased susceptibility to infection, bone marrow suppression and possible increased cancer risk, according to Merck Manuals.
