The degrees of cyclooxygenase (COX)-selectivity of various traditional non-steroidal anti-infammatory drugs (tNSAIDs) and coxibs (open circles). The concentrations required to inhibit COX-1 and COX-2 by 50% (IC50) have been measured using whole blood assays of COX-1 and COX-2 activity in vitro.18 The line indicates equivalent COX-1 and COX-2 inhibition. Drugs plotted below the line are more potent inhibitors of COX-2 than drugs plotted above the line. The distance to the line is a measure of selectivity. Lumiracoxib is the compound with the highest degree of selectivity for COX-2 as its distance to the line is the largest. Celecoxib and diclofenac have similar degrees of COX-2 selectivity, as their distances to the line are similar; however, diclofenac is active at lower concentrations and, thus, located more to the left. (Updated from FitzGerald GA, Patrono C. The coxibs, selective inhibitors of cyclooxygenase-2.
