The present invention relates to piperidine derivatives of formula (I) ##STR00001## specifically 2-(R)-(4-Fluoro-2-methyl-phenyl)-4-(S)-((8aS)-6-oxo-hexahydro-pyrrolo[1,2- -a]-pyrazin-2-yl)-piperidine-1-carboxylic acid [1-(R)-(3,5-bis-trifluoromethyl-phenyl)-ethyl]-methylamide maleate and pharmaceutical compositions thereof, useful in the treatment of conditions mediated by tachykinins.