There are described compounds of formula I, ##STR1## in which Ar.sub.1 and Ar.sub.2, which may be the same or different, each independently represent phenyl or pyridinyl, the phenyl or the pyridinyl each optionally being substituted by one or more of halogen; hydroxy; --COOR.sub.12 ; trihalomethyl; alkoxy C1 to 6; alkyl C1 to 6; --NR.sub.1 R.sub.2 ; alkoxy C1 to 6 substituted by --NR.sub.1 R.sub.2 or by phenyl; or alkyl C1 to 6 substituted by --NR.sub.1 R.sub.2 or by --COOR.sub.12 ;R.sub.1 and R.sub.2, which may be the same or different, each independently represent hydrogen or alkyl C1 to 6,R.sub.3 represents hydrogen, alkyl C1 to 6, alkanoyl C1 to 6, benzoyl, --COOR.sub.8, or --CONHR.sub.11,R.sub.4, R.sub.5, R.sub.6 and R.sub.7, which may be the same or different each independently represent hydrogen, alkyl C1 to 6 or phenyl,R.sub.8 represents alkyl C1 to 6 or aryl,R.sub.11 represents alkyl C1 to 6 or aryl,R.sub.12 represents hydrogen or alkyl C1 to 6, and pharmaceutically acceptable derivatives thereof.There are also described compositions containing the compounds and methods for their preparation.The compounds are indicated for use as pharmaceutical, eg antiinflammatory agents.