TNF alpha is a protein that is produced during the inflammatory response. It both starts as well as perpetuates inflammation. Increased levels of TNF are found in several inflammatory conditions including rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis. Drugs that block tumor necrosis factor (TNF) have been found to be particularly effective for the treatment of these serious types of inflammatory arthritis. Infliximab (Remicade) is a monoclonal chimeric antibody (part human, part mouse) directed against TNF alpha. Infliximab is approved for use alone or combined with methotrexate for treating moderate to severe rheumatoid arthritis. It also is approved for the treatment of active psoriatic arthritis and ankylosing spondylitis. Infliximab is administered intravenously. The recommended dose for the treatment of rheumatoid arthritis is 3 mg/kg as a single dose. The initial dose should be followed by additional 3 mg/kg doses two and six weeks after the first dose. The maintenance dose depends on the patients response. It can be increased to a maximum of 10 mg/kg every 4 weeks. The most common side effects of infliximab are upper respiratory tract infections, urinary tract infections, cough, rash, back pain, nausea, vomiting, abdominal pain, headache, weakness and fever. Infusion reactions, which are sometimes severe, may occur. Side effects such as blood pressure changes, chest pain, shortness of breath, rash, itching, fever and chills may occur during or shortly after administration. These reactions could possibly be due to an allergy to the drug. They are more common among patients who develop antibodies to infliximab and are less likely to occur in patients who are taking drugs that suppress the immune system, such as methotrexate. Infliximab should be discontinued if serious reactions occur. Serious infections have been reported with other drugs that block TNF- alpha, and infections have been reported during treatment with infliximab. Therefore, infliximab should not be used in patients with serious infections. Infliximab should be discontinued if a serious infection develops during treatment. Before starting infliximab, persons should have tuberculosis skin testing, because of reports of reactivation of tuberculosis in patients taking infliximab. There have been rare cases of serious liver injury in people taking infliximab. Screening for hepatitis B may be a good idea. Infliximab should not be used in patients with congestive heart failure or other significant heart disease. Approximately half of infliximab-treated patients in clinical trials developed a positive ANA during the trial compared with approximately one-fifth of placebo-treated patients. Anti-dsDNA antibodies were newly detected in approximately one-fifth of infliximab-treated patients compared with 0% of placebo-treated patients. Reports of lupus and lupus-like syndromes, however, remain uncommon. Decreased white and red blood cell and decreased platelet counts have been reported with infliximab. Vasculitis (inflammation of arteries) also has been reported. Patients with rheumatoid arthritis, particularly patients with very active disease and/or chronic exposure to immunosuppressive therapies, may be at a higher risk (up to several fold) than the general population for the development of lymphoma. It is not known whether anti-TNF therapy raises this level of risk. Infliximab should not be used in combination with anakinra (Kineret). |
