Bicyclic heterocyclic derivatives as 5-lipoxygenase inhibitors

A bicyclic heterocyclic derivative of the formula I

• wherein Q is benzimidazolyl or a hydrogenated derivative thereof, which may optionally bear one or two oxo or thioxo substituents and up to four further substituents selected from halogeno, hydroxy, cyano, amino, (1-4C)alkyl, (1-4C)alkoxy, fluoro-(1-4C)alkyl, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, amino-(1-4C)alkyl, (1-4C)alkylamino-(1-4C)alkyl, di-[(1-4C)-alkyl]amino-(1-4C)alkyl, phenyl and phenyl-(1-4C)alkyl, and
• wherein said phenyl or phenyl-(1-4C)alkyl substituent may optionally bear a substituent selected from halogeno, (1-4C)alkyl and (1-4C)alkoxy;
• wherein A.sup.1 is a direct link to X.sup.1 or is (1-3C) alkylene;
• wherein X.sup.1 is oxy, thio, sulphinyl, sulphonyl or imino;
• wherein Ar is phenylene which may optionally bear one or two substituents selected from halogeno, hydroxy, amino, nitro, cyano, carbamoyl, ureido, (1-4C)alkyl, (1-4C)alkoxy, (1-4C)alkylamino, di-[(1-4C)alkyl]amino, fluoro-(1-4C)alkyl and (2-4C)alkanoylamino;
• wherein R.sup.1 is (1-4C)alkyl, (3-4C)alkenyl or (3-4C)alkynyl;
• and
• wherein R.sup.2 and R.sup.3 together form a group of the formula --A.sup.2 --X.sup.2 --A.sup.3 -- which, together with the carbon atom to which A.sup.2 and A.sup.3 are attached,
• defines a ring having 5 to 7 ring atoms, wherein A.sup.2 and A.sup.3, which may be the same or different, each is (1-3C)alkylene and X.sup.2 is oxy, thio, sulphinyl or sulphonyl, and which ring may bear one, two or three substituents, which may be the same or different, selected from hydroxy, (1-4C)alkyl and (1-4C)alkoxy;
• or wherein R.sup.1 and R.sup.2 together form a group of the formula --A.sup.2 --X.sup.2 --A.sup.3 -- which, together with the oxygen atom to which A.sup.2 is attached and with the carbon atom to which A.sup.3 is attached, defines a ring having 5 to 7 ring atoms, wherein A.sup.2 and A.sup.3, which may be the same or different, each is (1-3C)alkylene and X.sup.2 is oxy, thio, sulphinyl or sulphonyl, and which ring may bear one, two or three (1-4C)alkyl substituents, and
• wherein R.sup.3 is (1-4C)alkyl, (2-4C)alkenyl or (2-4C)alkynyl, or a pharmaceutically-acceptable salt thereof.