Heterocyclic derivatives, processes for the use thereof and pharmaceutical compositions containing them

The invention provides compounds of the general formula (I) and physiologically acceptable salts and hydrates thereof, in which one of R1 and R2 represents hydrogen, halogen or a C1-4 alkyl group which may be optionally substituted by hydroxy or C1-4 alkoxy, and the other represents the group R4R5NAlk- in which Alk represents a straight or branched alkylene chain of 1 to 6 carbon atoms; R3, which may be in either the 2 or 3-position, represents the where X represents -CH2-, -O- or -S-; n represents zero, 1 or 2; m represents 2, 3 or 4; and R7 represents hydrogen, alkyl, alkenyl, aralkyl, or C2-6 alkyl substituted by hydroxy or alkoxy; and R8 represents hydrogen, alkyl, alkenyl, aralkyl, hydroxyalkyl, acyloxyalkyl, alkoxyalkyl, aryloxyalkyl, aralkyloxyalkyl, aminoalkyl, alkylaminoalkyl, dialkylaminoalkyl, hydroxy or alkoxy, or the group NR10R11; with the provisos that where R2 represents the group R4R5Nalk then R3 is in the 2-position; where R2 represents hydrogen then R3 is in the 3-position; and where R2 represents halogen or C1-4 alkyl optionally substituted by hydroxy or C1-4 alkoxy, and R3 is in the 2-position, then R8 cannot represent amino C1-6 alkyl, C1-6 alkylamino C1-6 alkyl, di-C1-6 alkylamino C1-6 alkyl or a group NR10R11. The compounds of formula (I) show pharmacological activity as selective histamine H2-antagonists.