Firocoxib is a coxib exhibiting high selectivity to inhibit COX-2. In vitro canine whole blood assays have demonstrated Firocoxib to be 350–430-fold more selective for COX-2 than for COX-1. COX-1 is constitutively expressed and enzymatically active in a variety of sites, including the stomach, intestine, kidneys, and platelets. COX-1 is the isoform largely responsible for the physiologic functions of eicosanoids, including gastric mucosal protection, renal blood flow, and vascular hemostasis. COX-2 expression is primarily induced by mediators such as serum growth factors, cytokines, and mitogens. COX-2 is primarily responsible for the synthesis of eicosanoids associated with inflammation.