Contents of this article
Peptides have gained growing attention in biomedical research due to their specificity, versatility, and therapeutic potential. Despite their promise, one of the biggest challenges in peptide science is ensuring effective administration. Peptides are fragile, highly susceptible to enzymatic degradation, and often show poor membrane permeability, which limits bioavailability. The method of delivery is often the deciding factor in whether a peptide achieves clinical success. Understanding the strengths and limitations of each strategy is essential for advancing peptide-based therapies.
Challenges in Peptide delivery
Delivering peptides effectively is complex. The main obstacles include:
- Enzymatic degradation: peptides given orally or subcutaneously are rapidly broken down by proteases in the digestive tract or bloodstream.
- Poor membrane permeability: due to size and hydrophilicity, many peptides struggle to cross biological barriers.
- Rapid renal clearance: small peptides are quickly eliminated, reducing half-life.
- Oral limitations: the gastrointestinal tract exposes peptides to acid and enzymes, leading to major bioactivity loss before absorption.
These factors make oral administration, while most convenient for patients, particularly difficult.
Peptide delivery methods
Lipid-based nanoparticles
Lipid-based nanoparticles such as liposomes can encapsulate peptides, protecting them from degradation and improving pharmacokinetics. The lipid bilayer enables sustained release, and functionalization with targeting ligands can direct peptides to specific tissues. However, challenges include stability, peptide leakage, and scale-up for manufacturing.
Polymeric and dendrimer nanoparticles
Polymeric nanoparticles and dendrimers can be engineered to release peptides in response to triggers like pH, temperature, or enzymes. They improve peptide stability and uptake, but their complexity raises challenges in reproducibility, large-scale production, and regulatory approval.
Microneedle arrays
Microneedle (MN) arrays are a minimally invasive option that bypasses the skin barrier. Dissolving or coated microneedles deliver peptides directly into systemic circulation without the pain of traditional injections. Research has shown success with insulin and growth hormone, but limitations include dose consistency and peptide stability during storage.
Invasomes and transdermal delivery
Invasomes are lipid vesicles enhanced with penetration enhancers like terpenes and ethanol to increase peptide absorption through the skin. They avoid needle use and reduce infection risk but are limited by peptide size and hydrophilicity; small, lipophilic peptides permeate better than large hydrophilic ones.
Oral delivery enhancements
Oral delivery is still the “holy grail” of peptide administration. Strategies such as enteric coatings, enzyme inhibitors, and absorption enhancers protect peptides from stomach acid and boost uptake. Nanoparticle encapsulation and mucoadhesive systems also show promise. Still, only a limited number of peptides are suitable for oral use today.
Bioprinting and controlled-release systems
Bioprinting uses hydrogels and self-assembling peptides to create 3D scaffolds that release peptides in a controlled manner. This approach mimics the extracellular matrix, supporting stability and localized therapy. While precise, it faces hurdles in reproducibility, large-scale manufacturing, and regulation.
Factors affecting delivery success
The effectiveness of any delivery system depends on:
- Peptide properties: molecular size, charge, and hydrophobicity.
- Formulation stability: resistance to proteases, storage conditions.
- Administration route: matching pharmacokinetics with delivery goals.
The most successful strategies combine protection from degradation, enhanced absorption, and controlled release. Methods lacking one of these aspects often fail to achieve therapeutic plasma levels.
Peptides are highly promising therapeutic agents but remain limited by their fragility and low bioavailability. Cutting-edge delivery methods including nanoparticles, microneedle arrays, invasomes, oral formulations, and bioprinting systems, are steadily overcoming these barriers. Each method brings its own trade-offs, but as technology advances, peptide delivery will continue to improve, unlocking broader clinical applications.
Research sources:
Therapeutic peptides and their delivery using lipid-based nanoparticles
Jui-Hung Yen, Chun-Chun Chang, Tien-Yuan Wu, Chin-Hao Yang, Hao-Jen Hsu and Je-Wen Liou. Published in Tzu Chi Medical Journal 2025 | DOI: 10.4103/tcmj.tcmj_321_24
Lipid-Polymer Hybrid Nanoparticles as a Smart Drug Delivery System for Peptide/Protein Delivery
Alharith A. A. Hassan, Eslam Ramadan, Katalin Kristó, Géza Regdon, Jr. and Tamás Sovány. Published in MDPI Pharmaceutics 2025 | DOI: 10.3390/pharmaceutics17060797
Yao Li, Qiu Chen, Tingting Wang, Zengkai Ji, Sagar Regmi, Haibin Tong, Jian Ju and Aifang Wang. Published in Journal of Nanobiotechnology 2025 | DOI: 10.1186/s12951-025-03432-9
Invasome: A Novel Nanocarrier for Transdermal Drug Delivery