Amide derivative

An amide derivative of formula (I) or a salt thereof,

• wherein:
• Z represents 1,2,4-oxadiazol-3-yl, 4-oxazolyl, 1,2,3-triazol-2yl or 2-pyridyl group;
• A represents a substituted or unsubstituted aryl group , a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted saturated hydrocarbon ring-fused aryl group or a substituted or unsubstituted saturated heterocyclic ring-fused aryl group, provided that the saturated hydrocarbon ring-fused aryl or saturated heterocyclic ring-fused aryl group is bonded to a nitrogen atom via a carbon atom in an aromatic ring;
• X represents -CO- or -S(O)2-;
• R3represents a substituted or unsubstituted alkyl , a substituted or unsubstituted alkenyl, a substituted or unsubstituted alkenyl , a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted cycloalkenyl, a substituted or unsubstituted aryl, or a substituted or unsubstituted heterocyclic group, or NRaRb;
• and
• Ra and Rb are the same or different from each other and represents H, a lower alkyl, lower alkenyl, lower alkenyl, cycloalkyl, cycloalkenyl, aryl, 5- or 6-membered monocyclic heteroaryl which has 1 to 4 hetero atoms selected from a group consisting of N, S and O, or lower alkylene-aryl group.