Abstract: A compound of Formula (I) and pharmaceutically and/or veterinarily acceptable derivatives thereof, wherein R1 is H, C1-6alkyl, —C(X)Y, C3-8cycloalkyl, aryl, het, aryl-C1-4alkyl or het-C1-4alkyl, wherein the cycloalkyl, aryl or het groups are optionally substituted by at least one substituent independently selected from C1-8alkyl, C1-8alkoxy, OH, halo, CF3, OCF3, SCF3, hydroxy-C1-6alkyl, C1-4alkoxy-C1-6alkyl and C1-4alkyl-S—C1-4alkyl; R2 is aryl or heteroaryl, each optionally substituted by at least one substituent independently selected from C1-8alkyl, C1-8alkoxy, OH, halo, CF3, OCF3, SCF3, hydroxy-C1-6alkyl, C1-4alkoxy-C1-6alkyl and C1-4alkyl-S—C1-4alkyl; R3 is C1-6alkyl, C3-8cycloalkyl, C3-8cycloalkyl-C1-6alkyl, aryl, het, aryl-C1-4alkyl or het-C1-4alkyl, wherein the cycloalkyl, aryl or het groups are optionally substituted by at least one substituent independently selected from C1-6alkyl, C1-6alkoxy, OH, halo, CF3, OCF3, SCF3, hydroxy-C1-6alkyl, C1-4alkoxy —C1-6alkyl and C1-4alkyl-S—C1-4alkyl; X is S