MK-0812 Succinate is a potent and selective CCR2 antagonist with high affinity at CCR2 . In Vitro MK-0812 is a potent and selective CCR2 antagonist. MK-0812 completely blocks all MCP-1 mediated response in a concentration dependent manner, with an IC 50 of 3.2 nM. This value is similar to the potency observed for the inhibition of 125 I-MCP-1 binding by MK-0812 on isolated monocytes (IC 50 4.5 nM). In fact, MK-0812 not only completely blocks the shape change response to exogenous MCP-1, but also results in a monocyte forward scatter measurement below unstimulated or basal levels. The addition of MK-0812 to rhesus blood also inhibits MCP-1 induced monocyte shape change. The IC 50 for MK-0812 in whole blood assays is 8 nMMCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo MK-0812 (30 mg/kg, p.o.) reduces the frequency of Ly6G - Ly6C hi monocytes in the peripheral blood, while no impact on circulating Ly6G + Ly6C + neutrophil frequency is observed. In addition, MK-0812 treatment causes a dose-dependent reduction in circulating Ly6C hi monocytes and a corresponding elevation in the CCR2 ligand CCL2 . MK-0812 is administered by continuous i.v. infusion to maintain a constant level of the drug in blood. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:CCR2