Derivatives of naphthyridine

Claim 1

3-Carboxy-4-oxo-1,40dihydro-1, 8-napthyridines of the formula ##STR5## wherein R 1 is selected from the group consisting of straight and branched alkyl of 1-7 carbon atoms and cycloalkyl, Z stands for oxygen, n is 0 or 1, and R 2 is selected from the group consisting of the group OH; the group C 6 H 5 ; the group --NHR 1 wherein R 1 has the same definition as above; the group ##STR6## wherein R 3 is selected from the group consisting of straight and branched alkyl of 1-7 carbon atoms, cycloalkyl, NH 2 , NHNH 2 , OR 1 wherein R 1 has the same definition as above, phenyl, phenyl--OH and phenyl--NO 2 and wherein R 4 stands for O or NH; the group C 6 H 5 --R 1 wherein R 1 has the same definition as above; the group C 6 H 5 --Hal wherein Hal is a halogen; and a heterocyclic group selected from the group consisting of ##STR7## wherein R 1 has the same definition as above; and physiologically acceptable salts thereof.