A compound of formula (I), ** Formula ** or a pharmaceutically acceptable salt thereof, wherein Ar is selected from the group consisting of: 4-isobutylphenyl, 2- (2,6-dichlorophenylamino) phenyl, 3-isopropylphenyl , 3-pent-3-ylphenyl, 3-phenoxyphenyl, 3-benzoylphenyl, 3- acetylphenyl, 3- [CH3-CH (OH)] phenyl, 3- [C6H5-CH (OH)] phenyl and 3 (α-methylbenzyl ) phenyl, R is H, X represents: a linear or branched C1-C6 alkylene, optionally substituted in C1 with a -CO2R3 group or with a CONHR4 group in which R4 represents hydrogen, linear or branched C2-C6 alkyl or with a OR3 group, wherein R3 represents H, a linear or branched C1-C6 alkyl group, or a linear or branched C2-C6 alkenyl group； a group (CH2) m-B- (CH2) n, in which B is a CONH group or an oxygen atom, m is an integer from 1 to 3 and n is an integer from 2 to 3； or X, together with the N atom of the omega-amino group and with R1, forms a cycloaliphatic ring containing nitrogen selected from 1-methylpiperidin-4-yl and 1,5-tropan-3-yl； R1 and R2 are independently selected from the group consisting of hydrogen, a C2-C3 hydroxyalkyl group, linear or branched C1-C6 alkyl； or R1 and R2, together with the N atom to which they are attached, form a 3-7 membered heterocyclic ring containing nitrogen of formula (II) ** Formula ** in which p is an integer from 0 to 3, Y represents a single bond, CH2, O, S or an N-Rc group, in which Rc is H or C1-C4 alkyl, or, where R1 is as defined above, R2 represents a group of formula (III): ** Formula ** in which Ra is H and Rb is hydrogen, hydroxyl, C1-C4 alkyl or an NRdRe group in which Rd and Re are each independently H, C1-C4 alkyl； or Ra and Rb, together with the nitrogen atoms to which they are attached, form a 5-7 membered heterocyclic ring； or said compound is selected from (R) -2- (3-isobutyl) phenyl-N- [3- (dimethylamino) propyl] propionamide and (R), (R ', S') - 2- [3- (α -hydroxy-α-methylbenzyl) phenyl] -N- (3-dimethylaminopropyl) propionamide for use as a medicament for th
