The invention relates to compounds of the general formula (I) ##STR1## and physiologically acceptable salts, hydrates and bioprecursors thereof, in which Q represents a benzene ring in which incorporation into the rest of the molecule is through bonds at the 1- and 3- or 1- and 4- positions: Z represents one of the groups ##STR2## where X represents NCN, NSO.sub.2 Methyl, NSO.sub.2 Phenyl or CHNO.sub.2. The compounds show pharmacological activity as selective histamine H.sub.2 -antagonists.
The invention relates to compounds of the general formula (I) ##STR1## and physiologically acceptable salts or hydrates thereof, in which the substituents are defined later in the specification. The compounds show pharmacological activity as selective histamine H.sub.2 -antagonists.