Patent ID: 8592581

Claim:
A compound of formula (I), or a pharmaceutically acceptable salt thereof, wherein: R 1 and R 2 are each independently H, alkyl or haloalkyl; R 3 and R 4 are each independently H, alkyl, haloalkyl or aryl; R 5 is alkyl or cycloalkyl or cycloalkyl-alkyl, each of which may be optionally substituted with one or more OH groups; R 6 is selected from cyclopropylamino, cyclopropylmethylamino, cyclobutylamino, cyclobutylmethylamino and where one of X, Y and Z is N and the remainder are CR 9 ; R 7 , R 8 and each R 9 are independently H, alkyl or haloalkyl, wherein at least one of R 7 , R 8 and each R 9 is other than H.