MK-8318 is an effective and selective antagonist of the CRTh2 receptor (Ki: 5.0 nM).

CRTH2/DP2 receptor:5.0 nM (ki), cAMP:8.0 nM, CYP2D6:50 μM, CYP3A4:50 μM, β-arrestin:3.5 nM, CYP2C9:50 μM

MK-8318 suppresses β-arrestin, cAMP, CYP3A4, CYP2C9, and CYP2D6 (IC50s: 3.5±2.1 nM, 8.0±6.8 nM, 50 μM, 50 μM and 50 μM).

MK-8318 displays 76% LAR efficacy and 114% AHR efficacy. MK-8318 blocks late airway response (LAR) and airway hyperresponsiveness (AHR) after i.v. infusion at 1 mg/kg, in a sheep model. MK-8318 also shows good efficacy on BAL cells/pulmonary function from ovalbumin sensitized and challenged Brown Norway rats at 3, 10, and 30 mg/kg oral dosing.