Benzenesulphonamide derivatives

A benzenesulphonamide derivative of the formula I

• 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 and are attached, defines a ring having 5 or 6 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 or two substituents, which may be the same or different, selected from hydroxy, (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 or imino;
• wherein Ar is phenylene which may optionally bear one or two substituents selected from halogeno, hydroxy, amino, trifluoromethyl, (1-4C)alkyl and (1-4C)alkoxy;
• wherein R.sup.4 is a 5- or 6-membered monocyclic heterocyclic moiety containing one or two nitrogen heteroatoms and optionally containing a further heteroatom selected from nitrogen, oxygen and sulphur, or a hydrogenated derivative thereof, which heterocyclic moiety may optionally bear one or two substituents selected from halogeno, hydroxy, amino, cyano, nitro trifluoromethyl, carbamoyl, oxo, thioxo, (1-4C)alkyl, (1-4C)alkoxy and (2-4C)alkanoylamino;
• R.sup.5 is hydrogen or (1-4C)alkyl;
• and
• R.sup.6 is hydrogen, halogeno, trifluoromethyl, (1-4C)alkyl or (1-4C)alkoxy;
• or a pharmaceutically-acceptable salt thereof.