A cyclic peptide of forumula (I) X GQRETPEGAEAKPWY X wherein X comprises an amino acid (sequence) with 1 to 4 members including natural or unnatural amino acids and X2 comprises a natural amino acid and wherein X contains the N terminal amino acid on the left in position 1 and X contains the C terminal amino acid in the last position on the right in the form of a lyophilisate without additives and/or stabilizers and the use thereof.