Cyclic octapeptides and pharmaceutical preparations thereof, as well as processes for their manufacture, and their use

Cyclic octapeptides of the formula (I) in which Aaa represents a radical of a straight-chained alpha , omega -diaminoalkanoic acid having from 4 to 7 carbon atoms, trp represents a radical L-Trp or, especially, D-Trp, or a radical derived therefrom, which carries a halogen atom in the indole nucleus, AcA represents an acyl radical Ac of an optionally substituted carboxylic acid which is positioned at the omega -amino group, or represents an amidino group or hydrogen, and AcB represents an acyl radical Ac1 of an amino acid or of an oligopeptide which is positioned at the epsilon -amino group, or, preferably, represents hydrogen, as well as physiologically tolerable salts and therapeutically acceptable complexes thereof can be used as antidiabetics and for the treatment of gastro-intestinal bleeding in an analogous manner to somatostatin. They can be obtained by conventional processes of peptide chemistry, especially by the cyclization of corresponding linear peptides.