YM49598 is a novel non-peptide tachykinin receptor antagonist. YM49598 exhibited high binding affinities at NK(2) (pK(i) = 9.94 +/- 0.03) and NK(1) (pK(i) = 9.09 +/- 0.02) receptors, respectively. YM-49598 was almost inactive but produced a potent inhibition (IC(50) = 11 +/- 7 microg x kg(-1)) of the contraction of the rat urinary bladder induced by challenge with the NK(1)-selective receptor agonist [Sar9,Met(O(2))11]substance P sulphone (0.3 microg x kg(-1)).
