Compounds of the general formula (I) ##STR1##

are described wherein R¹ and R², which may be the same or different, is each a hydrogen atom or a CF₃, CF₂H or CFH₂ group, provided that when one of R¹ and R² is a hydrogen atom, then the other is a CF₃, CF₂H or CFH₂ group, and the salts, solvates or hydrates thereof. Compounds of the invention are potent MMP inhibitors which advantageously do not cause tendonitis in a relevant animal model. Compounds of the invention may be expected to be of use in medicine, especially where the avoidance of side effects, such as joint pain, is desired.