There is provided a compound of formula (I), wherein X, Y, Z, R
1
, R
2
, R
3
, R
4
, and R
5
have meanings given in the description, and pharmaceutically-acceptable salts thereof, which compounds are useful in the treatment of diseases in which inhibition of the activity of microsomal prostaglandin E synthase-1 is desired and/or required, and particularly in the treatment of inflammation.