A compound of formula or a pharmacologically acceptable salt thereof wherein: Ar 1 and Ar 2 are each phenyl; a is an integer of from 0 to 1; R 1 is selected from the group consisting of alkyl having from 1 to 4 carbon atoms, halogen, haloalkyl having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, haloalkoxy having from 1 to 4 carbon atoms, and hydroxyl; b is 3; R 2 is selected from the group consisting of halogen, haloalkyl having from 1 to 3 carbon atoms, and haloalkoxy having from 1 to 3 carbon atoms, and where each substituent R 2 may be the same or different; W is NR 4a, wherein R 4a is selected from the group consisting of hydrogen, alkyl having from 1 to 3 carbon atoms and phenyl; Y and Z are each a group of formula (CR 5a R 5b) n1 wherein each n1 is 0; R 5a and R 5b are the same or different and each is selected from the group consisting of hydrogen atoms, alkyl groups, cycloalkyl groups, aryl groups and heteroaryl groups; V is (CR 3a R 3b) p CON(R 3b)X, wherein said group is in the 3- ( meta) or 4- ( para) position with respect to the substituent Z, wherein p is an integer of 0 or 1, R 3a and R 3b are the same or different and each is selected from the group consisting of hydrogen and alkyl having from 1 to 4 carbon atoms, and X is a substituent selected from the group consisting of hydroxyalkyl having from 1 to 4 carbon atoms, polyalkylene glycol residues of general formula HO-[(CR 6a R 6b) c1 -O-(CR 6c R 6d) c2] c3 - wherein c1 and c2 are the same or different and each is an integer of from 1 to 3, c3 is an integer of from 1 to 10 and R 6a, R 6b, R 6c and R 6d may be the same or different and each is a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms. Ar 1 and Ar 2 are each phenyl; a is an integer of from 0 to 1; R 1 is selected from the group consisting of alkyl having from 1 to 4 carbon atoms, halogen, haloalkyl having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, haloalkoxy having from 1 to 4 carbon atoms, and hydroxyl; b is 3; R 2 is selected from the group consisting of halogen, haloalkyl having from 1 to 3 carbon atoms, and haloalkoxy having from 1 to 3 carbon atoms, and where each substituent R 2 may be the same or different; W is NR 4a, wherein R 4a is selected from the group consisting of hydrogen, alkyl having from 1 to 3 carbon atoms and phenyl; Y and Z are each a group of formula (CR 5a R 5b) n1 wherein each n1 is 0; R 5a and R 5b are the same or different and each is selected from the group consisting of hydrogen atoms, alkyl groups, cycloalkyl groups, aryl groups and heteroaryl groups; V is (CR 3a R 3b) p CON(R 3b)X, wherein said group is in the 3- ( meta) or 4- ( para) position with respect to the substituent Z, wherein p is an integer of 0 or 1, R 3a and R 3b are the same or different and each is selected from the group consisting of hydrogen and alkyl having from 1 to 4 carbon atoms, and X is a substituent selected from the group consisting of hydroxyalkyl having from 1 to 4 carbon atoms, polyalkylene glycol residues of general formula HO-[(CR 6a R 6b) c1 -O-(CR 6c R 6d) c2] c3 - wherein c1 and c2 are the same or different and each is an integer of from 1 to 3, c3 is an integer of from 1 to 10 and R 6a, R 6b, R 6c and R 6d may be the same or different and each is a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms.