YM49598 is a tachykinin receptor antagonist. YM49598 exhibited high binding affinities at NK(1) (pK(i) = 9.09 + - 0.02) and NK(2) (pK(i) = 9.94 + - 0.03) receptors, respectively. YM49598 was almost inactive but produced a potent inhibition (IC(50) = 11 +