Abstract: A compound of Formula (I), and its pharmaceutically acceptable salt or salts and physiologically hydrolysable derivatives in free form or salt form: wherein R1 is independently selected from F, Cl, Br, CN, NH2, OH, CHO, COOH, oxo, C1-4alkyl, C1-4alkoxy, CONH2 (optionally mono- or di-substituted by C1-4alkyl) and SO2NH2, R2 is independently selected from C1-6allkyl substituted by R3 wherein the C1-6alkyl chain optionally comprises one or two heteroatoms select from O; R3 is selected from aryl, C3-6cycloalkyl, C3-6heterocyclyl and C3-6heteroaryl, wherein the heterocyclyl and heteroaryl rings are nitrogen containing; and wherein R3 is optonally substituted by one or more groups selected from R1; n1 is zero or an integer from 1 to 2; n2 is an integer from 1 to 2; and the sum of n1 and 2 is less than or equal to 2; R5 is selected from any group defined for R1 and R2; R6a and R6b are independently selected from H or C1-4alkyl; R7 is independently selected from F, Cl, Br, CN, NH2, OH, CHO, COOH, oxo, C1-4al