Sodium [2′-[(cyclopropanecarbonyl-ethyl-amino)-methyl]-4′-(6-ethoxy-pyridin-3-yl)-6-methoxy-biphenyl-3-yl]-acetate (AM432): A potent, selective prostaglandin D₂ receptor antagonist

Compound 21 (AM432) was identified as a potent and selective antagonist of the DP₂ receptor (CRTH2). Modification of a bi-aryl core identified a series of tri-aryl antagonists of which compound 21 proved a viable clinical candidate. AM432 shows excellent potency in a human whole blood eosinophil shape change assay with prolonged incubation, a comparatively long off-rate from the DP₂ receptor, excellent pharmacokinetics in dog and in vivo activity in two mouse models of inflammatory disease after oral dosing.