Updated publication reference for PubMed record(s): 31051282. The affinity purification/MS identification methodology reported here can be viewed as a routine pharmacoproteomic approach to investigate the serum interactome of peptide drugs, identifying proteins affecting bioavailability and thus assisting the peptide drug development process. The specific results described here enlighten the serum stability issues of peptide Ctn[15-34] and ratifiy its promising future as an anti-infective lead.