Compounds of the formula I wherein R1 is C1-C6alkyl, C1-C6haloalkyl, C3-C6cycloalkyl, wherein C3-C6cycloalkyl is optionally substituted with CF3, methyl, ethyl or one or two F； R2a and R2b are independently H, F and CH3O； R3 is F or CH3； or a pharmaceutically acceptable salt, hydrate or N-oxide thereof, for the use in the prophylaxis or treatment of a disorder characterised by inappropriate expression or activation of cathepsin S.一種式I化合物，其中R1為C1-C6烷基、C1-C6鹵烷基、C3-C6環烷基，其中C3-C6環烷基視情況經CF3、甲基、乙基或一或兩個F取代；R2a及R2b獨立地為H、F及CH3O；R3為F或CH3；或其醫藥學上可接受之鹽、水合物或N-氧化物，其係用於預防或治療以組織蛋白酶S之不適當表現或活化為特徵之病症。
