A compound of formula (I) or a pharmaceutically acceptable salt thereof: ##STR1## wherein: R.sub.1 and R.sub.2 are independently hydrogen, C.sub.1-6 alkyl or together are a group X which is C.sub.3-6 polymethylene optionally interrupted by O, S or NR.sub.6 wherein R.sub.6 is hydrogen or C.sub.1-6 alkyl;R.sub.3 is phenyl, optionally substituted by one or more substituents selected from halogen, CF.sub.3, nitro, C.sub.1-6 alkyl, C.sub.1-6 alkoxy, C.sub.1-6 alkylthio, C.sub.2-7 alkanoyl, carboxyl, C.sub.1-6 alkoxycarbonyl, cyano, CONR.sub.7 R.sub.8 wherein R.sub.7 and R.sub.8 are selected from hydrogen or C.sub.1-6 alkyl or together are a group X; NR.sub.9 R.sub.10 wherein R.sub.9 and R.sub.10 are selected from hydrogen, C.sub.1-6 alkyl, C.sub.2-7 alkanoyl or C.sub.1-6 alkylsulphonyl or together are a group X; SO.sub.2 NR.sub.11 R.sub.12 wherein R.sub.11 and R.sub.12 are selected from hydrogen or C.sub.1-6 alkyl or together are a group X or S(O).sub.m R.sub.13 wherein m is 1 or 2 and R.sub.13 is C.sub.1-6 alkyl;R.sub.4 and R.sub.5 are independently selected from hydrogen, C.sub.1-6 alkyl, cyano, amino, aminocarbonyl or aminocarbamoyl optionally substituted by one or two C.sub.1-6 alkyl groups or together are a group X, halogen, CF.sub.3, nitro, C.sub.1-6 alkoxy, C.sub.1-6 alkylthio, C.sub.2-7 alkanoyloxy, C.sub.1-6 alkoxy or hydroxy, or together are methylenedioxy or C.sub.3-5 polymethylene, having anti-inflammatory and/or anti-rheumatic activity, a process for their preparation and their use as pharmaceuticals.