<qa>  What is the active ingredient in a drug currently sold by the trade names Remicade,Background: Infliximab is the active ingredient in a drug currently sold by the trade names Remicade, Remsima and Inflectra. Infliximab neutralizes tumor necrosis factor TNF α, a chemical messenger cytokine in the immune system, and belongs to a class of drugs called TNF inhibitors. This class of drug comprises effective, biological agents used in the treatment of chronic inflammatory diseases. The use of TNF inhibitors is increasing, and infliximab is the third bestselling drug by value in Norway in 2013. By being a recombinant monoclonal antibody with a murine region, infliximab is associated with infusion reactions. 8-55 of patients receiving infliximab have an infusion reaction. Infusion reactions are unintended reactions that occur during infusion of the drug and up to 14 days after. The incidence varies widely in different studies and seems difficult to determine due to variations in reporting of reactions, different definitions of reactions and retrospective data collection. Protective factors, risk factors and the causes of the reactions are not well known. Different treatment strategies are being used, but evidence of efficacy varies. 