A compound of formula wherein R 1 is C 1-6 alkyl optionally substituted by a hydroxyl group; R 2 is H or C 1-6 alkyl optionally substituted by a hydroxyl group; R 3 is H; Ar is a naphthyl or a phenyl ring either of which may be optionally substituted by one or more (for example 1 or 2) groups independently selected from C 1-6 alkyl, C 1-6 alkoxy, amino, and C 1-4 mono or di-alkyl amino; X is pyridine or pyrimidine; Q is selected from: a) a saturated or unsaturated, branched or unbranched C 1-10 alkyl chain, wherein at least one carbon (for example 1, 2 or 3 carbons, suitably 1 or 2, in particular 1 carbon) is replaced by a heteroatom selected from O, N, and S p, wherein said chain is optionally, substituted by one or more groups (for example 1, 2 or 3 groups) independently selected from oxo, halogen, an aryl group, a heteroaryl group, a heterocyclyl group and a C 3-8 cycloalkyl group, each aryl, heteroaryl, heterocyclyl or C 3-8 cycloalkyl group bearing 0 to 3 substituents selected from halogen, hydroxyl, C 1-6 alkyl, C 1-6 alkoxy, C 1-6 haloalkyl, amino, C 1-4 mono or di-alkyl amino, C 1-4 mono or di-acyl amino, S qC 1-6 alkyl, C 0-6 alkylC C 1-6 alkyl and C 0-6 alkylC C 1-6 heteroalkyl, with the proviso that the atom linked directly to the carbonyl in -NR 3 C - is not an oxygen or a sulfur atom; and b) a C 0-8 alkyl-heterocycle said heterocyclyl group comprising at least one heteroatom (for example 1, 2 or 3, suitably 1 or 2, in particular 1 heteroatom) selected from O, N, and S, and is optionally substituted by one, two or three groups independently selected from halogen, hydroxyl, C 1-6 alkyl, C 1-6 alkoxy, C 1-6 haloalkyl, amino, C 1-4 mono or di-alkyl amino, C 1-4 mono or di-acyl amino, S q C 1-6 alkyl, C 0-6 alkylC C 1-6 alkyl and C 0-6 alkylC C 1-6 heteroalkyl; p is 0, 1 or 2; and q is 0, 1 or 2 or a pharmaceutically acceptable salt thereof, including all stereoisomers, tautomers and isotopic derivatives thereof. wherein R 1 is C 1-6 alkyl optionally substituted by a hydroxyl group; R 2 is H or C 1-6 alkyl optionally substituted by a hydroxyl group; R 3 is H; Ar is a naphthyl or a phenyl ring either of which may be optionally substituted by one or more (for example 1 or 2) groups independently selected from C 1-6 alkyl, C 1-6 alkoxy, amino, and C 1-4 mono or di-alkyl amino; X is pyridine or pyrimidine; Q is selected from: a) a saturated or unsaturated, branched or unbranched C 1-10 alkyl chain, wherein at least one carbon (for example 1, 2 or 3 carbons, suitably 1 or 2, in particular 1 carbon) is replaced by a heteroatom selected from O, N, and S p, wherein said chain is optionally, substituted by one or more groups (for example 1, 2 or 3 groups) independently selected from oxo, halogen, an aryl group, a heteroaryl group, a heterocyclyl group and a C 3-8 cycloalkyl group, each aryl, heteroaryl, heterocyclyl or C 3-8 cycloalkyl group bearing 0 to 3 substituents selected from halogen, hydroxyl, C 1-6 alkyl, C 1-6 alkoxy, C 1-6 haloalkyl, amino, C 1-4 mono or di-alkyl amino, C 1-4 mono or di-acyl amino, S qC 1-6 alkyl, C 0-6 alkylC C 1-6 alkyl and C 0-6 alkylC C 1-6 heteroalkyl, with the proviso that the atom linked directly to the carbonyl in -NR 3 C - is not an oxygen or a sulfur atom; and b) a C 0-8 alkyl-heterocycle said heterocyclyl group comprising at least one heteroatom (for example 1, 2 or 3, suitably 1 or 2, in particular 1 heteroatom) selected from O, N, and S, and is optionally substituted by one, two or three groups independently selected from halogen, hydroxyl, C 1-6 alkyl, C 1-6 alkoxy, C 1-6 haloalkyl, amino, C 1-4 mono or di-alkyl amino, C 1-4 mono or di-acyl amino, S q C 1-6 alkyl, C 0-6 alkylC C 1-6 alkyl and C 0-6 alkylC C 1-6 heteroalkyl; a) a saturated or unsaturated, branched or unbranched C 1-10 alkyl chain, wherein at least one carbon (for example 1, 2 or 3 carbons, suitably 1 or 2, in particular 1 carbon) is replaced by a heteroatom selected from O, N, and S p, wherein said chain is optionally, substituted by one or more groups (for example 1, 2 or 3 groups) independently selected from oxo, halogen, an aryl group, a heteroaryl group, a heterocyclyl group and a C 3-8 cycloalkyl group, each aryl, heteroaryl, heterocyclyl or C 3-8 cycloalkyl group bearing 0 to 3 substituents selected from halogen, hydroxyl, C 1-6 alkyl, C 1-6 alkoxy, C 1-6 haloalkyl, amino, C 1-4 mono or di-alkyl amino, C 1-4 mono or di-acyl amino, S qC 1-6 alkyl, C 0-6 alkylC C 1-6 alkyl and C 0-6 alkylC C 1-6 heteroalkyl, with the proviso that the atom linked directly to the carbonyl in -NR 3 C - is not an oxygen or a sulfur atom; and each aryl, heteroaryl, heterocyclyl or C 3-8 cycloalkyl group bearing 0 to 3 substituents selected from halogen, hydroxyl, C 1-6 alkyl, C 1-6 alkoxy, C 1-6 haloalkyl, amino, C 1-4 mono or di-alkyl amino, C 1-4 mono or di-acyl amino, S qC 1-6 alkyl, C 0-6 alkylC C 1-6 alkyl and C 0-6 alkylC C 1-6 heteroalkyl, b) a C 0-8 alkyl-heterocycle said heterocyclyl group comprising at least one heteroatom (for example 1, 2 or 3, suitably 1 or 2, in particular 1 heteroatom) selected from O, N, and S, and is optionally substituted by one, two or three groups independently selected from halogen, hydroxyl, C 1-6 alkyl, C 1-6 alkoxy, C 1-6 haloalkyl, amino, C 1-4 mono or di-alkyl amino, C 1-4 mono or di-acyl amino, S q C 1-6 alkyl, C 0-6 alkylC C 1-6 alkyl and C 0-6 alkylC C 1-6 heteroalkyl; p is 0, 1 or 2; and q is 0, 1 or 2