Abstract: The present invention relates to excipients for stabilizing active agents, in particular peptides, polypeptides, nucleic acids, viruses, virus-like particles, proton pump inhibitors and antibiotics. The excipient reduces aggregate and/or particle formation in preparations comprising said agents. The excipient is a diamide of a dicarboxylic acid comprising at least one N—H amido group, at least one unsubstituted or substituted N-hydroxyethylamido group and/or at least one unsubstituted N-hydroxymethylamido group. In particular, the excipient is N,N,N?,N?-tetrakis-(2-hydroxyethyl) adipinic acid amide.