Peptide is a term applied to small proteins comprised of short chains of amino acids (roughly 40 or fewer). The body uses a wide variety of peptides as hormones and signaling molecules to stimulate and regulate key biological pathways. Well-known examples of natural peptides include insulin, endorphins, and somatropin (growth hormone).
Peptide medicines can be used to replace or mimic the functions of naturally occurring peptides or to emulate the ability of peptides to engage targets in a highly potent and selective manner. Some peptide therapies can be made using chemical processes, while others are produced inside genetically modified cells.