Cyclic peptide of formulaI,X1-GQRETPEGAEAKPWY-X2whereinX1 comprises an amino acid (sequence), with 1 to 4 members, comprising natural and unnatural amino acids, and X2 comprises a natural amino acid, and wherein X1 comprises the N-terminal amino acid left in position 1, and X2 the C-terminal amino acid in the ultimate, right position, in the form of a lyophilisate without additives and/or stabilizers and its use.