Phenoyalkylpiperazine derivatives

A compound selected from those of formula (I):

• ##STR17## in which Ar represents phenyl, naphthyl, but Ar is not trisubstituted phenyl when RB is methyl, substituted phenyl or substituted naphthyl,
• n represents 1,
• RB represents alkyl, A represents a single bond and RA and RC, which are identical or different, represent, independently of one another, hydrogen or a group chosen from halogen, alkyl, alkyl substituted by one or a number of halogens, and alkoxy,
• it being understood that, except when otherwise mentioned,
• the terms "alkyl" and "alkoxy" denote linear or branched saturated groups having 1 to 6 carbon atoms inclusive,
• the term "substituted" concerning the phenyl and naphthyl substituents means that the latter can be substituted by one to three groups chosen from hydroxyl, alkyl, alkyl substituted by one or a number of halogens, alkoxy and halogen,
• an optical isomer thereof in the pure form or in the form of a mixture, and an addition salt thereof with a pharmaceutically-acceptable acid or base.