SCH 546738 is a potent, orally active and non-competitive CXCR3 antagonist, the affinity constant ( K i ) of SCH 546738 binding to human CXCR3 receptor is determined to be 0.4 nM in multiple experiments. In Vitro The affinity of SCH 546738 binding to human CXCR3 receptor is determined by competition binding analysis using 35 S radiolabeled SCH 535390 (a sulfonamide analog of the CXCR3 compound series with a K d of 0.6 nM) as a competitive tracer. In addition, SCH 546738 displaces radiolabeled CXCL10 and CXCL11 from human CXCR3 with IC 50 ranging from 0.8 to 2.2 nM in a non-competitive manner. SCH 546738 potently and specifically inhibits CXCR3-mediated chemotaxis in human activated T cells with IC 90 about 10 nM. MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo SCH 546738 has strong cross-species activities with IC 50 of 1.3 nM, 6.4 nM, 5.9 nM and 4.2 nM in inhibiting the binding of [ 125 I]hCXCL10 to CXCR3 of monkey, dog, mouse and rat origin, respectively. SCH 546738 is a selective and potent CXCR3 antagonist with a good PK for in vivo studies . MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:Human CXCR3 0.4 nM (Ki)