sentences:  First, the ion-pair site interactivity with the bridgehead nitrogen; second, the accessory binding site interactivity with the benzhydryl group; and third, the specific site interactivity with the (2-methoxybenzyl) amino side chain.Studies have shown that compounds with piperidine ring have selectivity for NK1 receptor over NK2, NK3, opioid and 5-HT receptors.By adding an N-heteroaryl-2-phenyl-3-(benzyloxy) group to the piperidine, a selective NK1 receptor antagonist is produced.