The authors recently described the synthesis and characterization of MDL 105,212, a non peptide tachykinin antagonist with high affinity for NK1 and NK2 receptors.Here, the authors report the synthesis and structure-activity relationships for a series of analogs of MDL 105,212, I (Ar1 = 3-ClC6H4, 4-FC6H4, 3-pyridyl, etc., Ar2 = Ph, 3-MeOC6H4, 4-FC6H4, 3-, 4-pyridyl, R1R2N, = H2N, piperidino, morpholino, 4-methylpiperidino) and II (Ar2 = Ph, 3-, 4-pyridyl, R1R2N = H2N, morpholino, 4-methylpiperidino), with regards to NK1 and NK2 receptor binding affinity, phys.-chem. characterization; in vitro absorption potential; in vitro metabolic stability; and efficacy in a capsaicin-challenge conscious guinea pig model after oral administration.