The invention provides the compounds of formula (I) ##STR1##

in which:

R¹ is selected from the group consisting of H, C_1-6alkyl, C_1-2alkyl substituted by one to five fluorine atoms, C_3-6alkenyl, C_3-6alkynyl, C_3-10cycloalkylC_0-6alkyl, C_4-12bridged cycloalkyl, A(CR⁴R⁵)_n and B(CR⁴R⁵)_n;

R² is C_1-2alkyl substituted by one to five fluorine atoms;

R³ is selected from the group consisting of C_1-6alkyl, NH₂ and R⁷CONH;

R⁴ and R⁵ are independently selected from H or C_1-6alkyl;

A is an unsubstituted 5- or 6-membered heteroaryl or an unsubstituted 6-membered aryl, or a 5- or 6-membered heteroaryl or a 6-membered aryl substituted by one or more R⁶;

R⁶ is selected from the group consisting of halogen, C_1-6alkyl, C_1-6alkyl substituted by one more fluorine atoms, C_1-6alkoxy, C_1-6alkoxy substituted by one or more F, NH₂SO₂ and C_1-6alkylSO₂;

B is selected from the group consisting of ##STR2##

where ##STR3##

defines the point of attachment of the ring;

R⁷ is selected from the group consisting of H, C_1-6alkyl, C_1-6alkoxy, C_1-6alkylOC_1-6alkyl, phenyl, HO₂CC_1-6alkyl, C_1-6alkylOCOC_1-6alkyl, C_1-6alkylOCO, H₂NC_1-6alkyl, C_1-6alkylOCONHC_1-6alkyl and C_1-6alkylCONHC_1-6alkyl; and

n is 0 to 4.

Compounds of formula (I) are potent and selective inhibitors of COX-2 and are of use in the treatment of the pain, fever and inflammation of variety of conditions and diseases.