Biologics that bind to tumor necrosis factor (TNF-α) include etanercept, adalimumab, infliximab, certolizumab, and golimumab. TNF-α inhibitors are used when arthritis is not well controlled with conventional DMARDs such as methotrexate. The body produces TNF-α during an injury. Fever, pain, swelling, and signs of inflammation are usually accompanied by the production of TNF-α. TNF-α inhibitors block the action of TNF in joints and other parts of the body. This reduces the inflammation and symptoms due to rheumatoid arthritis.
In a 12-month trial, the efficacy of different TNF-inhibitors was studied. At the end of 12 months, based on The Disease Activity Score (DAS), a good response was achieved by 59.6% of patients on adalimumab, 59.2% of patients on etanercept, and 51.9% of patients with infliximab. The DAS is a rheumatoid arthritis activity index measuring the severity of the disease based on information such as swollen and tender joints. In a different study, 6000 patients with active RA were enrolled. Responses were based on a standard measure of improvement set by American College of Rheumatology (ACR). For example, if there was a 70% improvement in RA symptoms, the results would be considered as ACR 70. In this study, 19 to 21% of patient with early RA and receiving methotrexate alone had ACR70 compared to 33 to 40% of patients on a combination of TNF-inhibitor and methotrexate therapy. The side effects of TNF-inhibitors as a class include injection site reactions (rash, redness, itching), infections, headache, and nausea.
Dosage of TNF-Inhibitors