Peptide
A peptide is a short chain of amino acids, the small building blocks that proteins are made from. GLP-1 and amylin are peptides. Peptides are bigger than most pill-type drugs but smaller than large proteins.
For experts
Therapeutic peptides are chains of amino acids, usually with molecular weights of about 500-5000 Da, occupying a space between small molecules and larger biologics. For US regulatory purposes, FDA defines a protein as an alpha amino acid polymer with a specific, defined sequence greater than 40 amino acids in size, so chains of 40 or fewer amino acids fall outside that definition of a protein; amylin, at 37 amino acids, is an example of a peptide hormone.
Sources (3)
- 01Therapeutic peptides: current applications and future directionsSignal Transduction and Targeted Therapy (PubMed Central, NCBI/NLM) · 2022-02-14 · accessed 2026-09-29
- 0221 CFR 600.3 - Definitions (including the definition of a protein)Electronic Code of Federal Regulations (eCFR), Office of the Federal Register · 2026-09-25 · accessed 2026-09-29
- 03Amylin: Pharmacology, Physiology, and Clinical PotentialPharmacological Reviews (indexed in PubMed, NCBI/NLM) · 2015-07 · accessed 2026-09-29