Histamine antagonist triadiazole derivatives, compositions, and method of use therefor

A compound of formula (1):

• ##STR7## or a pharmaceutically acceptable salt thereof, where R.sup.1 and R.sup.2 are the same or different and are hydrogen, C.sub.1-6 alkyl, C.sub.1-6 alkoxy or halogen;
• R.sup.3 is optionally substituted phenyl or optionally substituted pyridyl, where the optional substituents are one or more C.sub.1-6 alkyl, C.sub.1-6 alkoxy, or hydroxy groups or halogen atoms;
• or furanyl or thienyl optionally substituted by a C.sub.1-6 alkyl group;
• a is from 1 to 6;
• b is from 2 to 4;
• R.sup.4 is CH.sub.2 R.sup.5 where R.sup.5 is phenyl substituted by sulphonamido or a carboxyl group or an ester thereof, pyridyl substituted with a carboxyl group or an ester thereof and optionally further substituted with a C.sub.1-6 alkyl group, N-oxo-pyridyl optionally substituted with a C.sub.1-6 alkyl group, or an imidazolyl, pyridazinyl, pyrimidinyl, pyrazinyl or benzimidazolyl group;
• and
• r is 1 or 2.