compounds of the following formula wherein r 1 r 2 , n , ar 1 and a 2 are as defined in the specification , in vivo - hydrolysable precursors thereof , pharmaceutically acceptable salts thereof , the use in therapy and pharmaceutical compositions and methods of treatment using the same . the example compounds are 1 -- 1 - phenylethyl ) piperazine derivatives . the compounds are neurokinin 1 receptor antagonist and / or serotonin reuptake inhibitors , with medical indications for depression and other disorders