A compound of formula I or an enantiomer, diastereomer, tautomer or isotopic variant thereof; or a pharmaceutically acceptable salt or solvate thereof; wherein X is N or CR 1; Y is N or CR 2; R 1 is H, alkoxy, halo, triazolyl, thiazolyl, pyridazinyl, pyrimidinyl, oxazolyl, isoxazolyl, oxadiazolyl, pyridyl, phenyl or pyrazolyl, wherein triazolyl, thiazolyl, pyridazinyl, pyrimidinyl, oxazolyl, isoxazolyl, oxadiazolyl, pyridyl, phenyl or pyrazolyl is optionally substituted with up to two substituents selected from the group consisting of halo and alkyl; R 2 is H, alkyl, alkoxy, or halo; Z is NH, N-CH 3, N-CH 2 CH 3, N-CH 2 -cyclopropyl, N-C(=O)CH 3, N-CH 2 CH 2 OCH 3 or O; R 3 is H, alkyl, alkoxy, halo, triazolyl, thiazolyl, pyridazinyl, pyrimidinyl, oxazolyl, isoxazolyl, oxadiazolyl, pyridyl, phenyl or pyrazolyl, wherein triazolyl, thiazolyl, pyridazinyl, pyrimidinyl, oxazolyl, isoxazolyl, oxadiazolyl, pyridyl, phenyl or pyrazolyl is optionally substituted with up to two substituents selected from the group consisting of halo and alkyl; R 4 is H or alkyl; or R 3 and R 4, together with the atoms to which they are attached, form a 6-membered aryl ring or a 5- or 6-membered heteroaryl ring; R 5 is phenyl, pyridyl, pyrazinyl, benzoxazolyl, pyridazinyl, naphthyridinyl or pyrimidinyl, wherein the pyridyl, pyrazinyl, benzoxazolyl, pyridazinyl, naphthyridinyl or pyrimidinyl is optionally substituted with up to two groups selected from the group consisting of halo, alkoxy, hydroxymethyl and alkyl; and n is 1 or 2, wherein "alkyl" is a straight- or branched-chain alkyl group having from 1 to 12 carbon atoms in the chain or a mono-cyclic, non-aromatic hydrocarbon group having from 3 to 7 carbon atoms and is optionally substituted with one or more halogen atoms. X is N or CR 1; Y is N or CR 2; R 1 is H, alkoxy, halo, triazolyl, thiazolyl, pyridazinyl, pyrimidinyl, oxazolyl, isoxazolyl, oxadiazolyl, pyridyl, phenyl or pyrazolyl, wherein triazolyl, thiazolyl, pyridazinyl, pyrimidinyl, oxazolyl, isoxazolyl, oxadiazolyl, pyridyl, phenyl or pyrazolyl is optionally substituted with up to two substituents selected from the group consisting of halo and alkyl; R 2 is H, alkyl, alkoxy, or halo; Z is NH, N-CH 3, N-CH 2 CH 3, N-CH 2 -cyclopropyl, N-C(=O)CH 3, N-CH 2 CH 2 OCH 3 or O; R 3 is H, alkyl, alkoxy, halo, triazolyl, thiazolyl, pyridazinyl, pyrimidinyl, oxazolyl, isoxazolyl, oxadiazolyl, pyridyl, phenyl or pyrazolyl, wherein triazolyl, thiazolyl, pyridazinyl, pyrimidinyl, oxazolyl, isoxazolyl, oxadiazolyl, pyridyl, phenyl or pyrazolyl is optionally substituted with up to two substituents selected from the group consisting of halo and alkyl; R 4 is H or alkyl; or R 3 and R 4, together with the atoms to which they are attached, form a 6-membered aryl ring or a 5- or 6-membered heteroaryl ring; R 5 is phenyl, pyridyl, pyrazinyl, benzoxazolyl, pyridazinyl, naphthyridinyl or pyrimidinyl, wherein the pyridyl, pyrazinyl, benzoxazolyl, pyridazinyl, naphthyridinyl or pyrimidinyl is optionally substituted with up to two groups selected from the group consisting of halo, alkoxy, hydroxymethyl and alkyl; and n is 1 or 2, wherein "alkyl" is a straight- or branched-chain alkyl group having from 1 to 12 carbon atoms in the chain or a mono-cyclic, non-aromatic hydrocarbon group having from 3 to 7 carbon atoms and is optionally substituted with one or more halogen atoms.