Peptides are short chains of amino acids linked by covalent peptide bonds, typically composed of between 2 and 50 residues. When the chain reaches 10 to 20 amino acids, it is classified as an oligopeptide; beyond 20 it becomes a polypeptide, and chains longer than approximately 50 residues are generally considered proteins [1].

Despite their modest size, peptides operate at the center of biological signaling. The human body produces hundreds of endogenous peptides that regulate fundamental processes such as blood glucose homeostasis, reproduction, water balance, inflammation, and tissue repair. Among the most familiar are insulin, oxytocin, vasopressin, and glucagon [2].

Therapeutic peptides bridge the gap between small molecules and biologics through their programmable architectures and multifaceted biointerfaces. As of 2023, over 80 peptide drugs have gained global approval, with more than 200 peptides in clinical development.

— Signal Transduction and Targeted Therapy, Nature (2024)

How Peptides Work in the Body

Peptides typically exert their effects by binding to specific cell-surface receptors, which triggers a cascade of intracellular signaling events. This mechanism resembles that of larger biologics such as therapeutic proteins and monoclonal antibodies, but peptides offer distinct advantages: lower immunogenicity, reduced production costs, and enhanced tissue penetration due to their smaller molecular weight [3].

Because peptides are metabolized into their constituent amino acids, they leave no foreign residue in the body. This clean metabolic profile is one reason they have become a rapidly growing class of therapeutic agents.

The Rise of Peptide Therapeutics

The global peptide drug market reached approximately USD 42 billion in 2022 and is projected to grow at a compound annual growth rate of 10% through 2032 [4]. Between 2016 and 2022, the U.S. Food and Drug Administration approved 26 peptide drugs, and more than 200 additional peptides are currently in clinical development. An additional 400 to 600 peptides remain in preclinical research.

This expansion is driven by breakthroughs in peptide engineering, including cyclization, D-amino acid substitution, N-methylation, and PEGylation, all of which enhance stability and bioavailability [5].

Key Therapeutic Areas

• Metabolic disorders, including type 2 diabetes and obesity (e.g., semaglutide, tirzepatide)
• Oncology and targeted drug delivery
• Infectious diseases and antimicrobial resistance
• Tissue regeneration and wound healing
• Neurology and cognitive function

References

[1] Wang L., et al. Therapeutic peptides: current applications and future directions. Signal Transduct Target Ther. 2022;7(1):48. doi:10.1038/s41392-022-00904-4

[2] Muttenthaler M., King G.F., Adams D.J., Alewood P.F. Trends in peptide drug discovery. Nat Rev Drug Discov. 2021;20(4):309-325.

[3] Lau J.L., Dunn M.K. Therapeutic peptides: Historical perspectives, current development trends, and future directions. Bioorg Med Chem. 2018;26(10):2700-2707.

[4] Rossino G., et al. Peptides as Therapeutic Agents: Challenges and Opportunities in the Green Transition Era. Molecules. 2023;28(20):7165. doi:10.3390/molecules28207165

[5] Zhu B., et al. Therapeutic Peptides: Recent Advances in Discovery, Synthesis, and Clinical Translation. Pharmaceuticals. 2025. PMC12154100.