Timapiprant sodium inhibits mast cell activation of Th2 lymphocytes and eosinophils. Timapiprant sodium is a potent and selective D prostanoid receptor 2 antagonist. Timapiprant sodium potently displaces [3H] PGD2 from human recombinant DP2 (Ki=13 nM), rat recombinant DP2 (Ki=3 nM), human native DP2 (Ki=4 nM).