Self-Emulsifying Lipid System Achieves 12% Oral Bioavailability for a Model Polypeptide | Research

The takeaway

Self-emulsifying inverted lipid phases achieved 12.1% oral bioavailability for a model polypeptide in rats, compared to only 1.5% without emulsifying agents, demonstrating the need for bile salt-independent emulsification.

12.1% oral bioavailability
Self-emulsifying dry lipid formulation achieved remarkably high polypeptide absorption vs 1.5% without emulsification

What the researchers found

Self-emulsifying ILP (se-ILPdry) achieved 12.10% oral bioavailability for HRP polypeptide vs 1.54% for non-emulsifying ILPdry, with rapid and complete emulsification in gastric and intestinal fluids.

Why it matters

Achieving 12% oral bioavailability for a polypeptide is remarkable and could enable oral formulations of injectable peptide drugs, improving patient compliance.

How the study worked

Formulation development of ILP and se-ILP (dry and wet), emulsification characterization via turbidity in bile salt media, kinetics in simulated GI fluids, and in vivo oral pharmacokinetics in rats using HRP as model polypeptide.

What this study cannot tell us

Tested with HRP as model polypeptide, which may not predict results for therapeutic peptides. Rat GI conditions differ from human. Long-term stability of formulations not assessed.

How to read the evidence

Well-designed formulation study with systematic in vitro characterization and in vivo validation. Strong proof-of-concept needing therapeutic peptide validation.

When this study was published

Published in 2025.

The bigger picture

Self-emulsifying lipid systems could become a general platform for oral delivery of peptide and protein drugs that currently require injection.

Questions still open

Would this se-ILP system work for therapeutic peptides like insulin or GLP-1 drugs?
How does formulation stability affect bioavailability over shelf life?
Can the dry formulation be converted to oral capsules for human use?

Common questions

Why is 12% bioavailability impressive for an oral peptide?

Most peptide drugs have less than 1% oral bioavailability because they're destroyed in the gut. Achieving 12% means this lipid delivery system protects the peptide and helps it absorb effectively — a major technical achievement.

Could this make injectable drugs into pills?

Potentially. If this technology works for therapeutic peptides like insulin or GLP-1 drugs, it could turn daily or weekly injections into oral medications, which most patients would prefer.

Read the original research

Oral (poly)peptide delivery: On the emulsifying properties of inverted lipid phases under gastrointestinal conditions.

Journal of controlled release : official journal of the Controlled Release Society, 390, 114508

View on PubMed ↗Publisher’s paper ↗

Citation

Ebert, Melanie Lena; Postina, Annika; Schmidt, Marlene Ramona; Laffleur, Flavia; Kali, Gergely; Bernkop-Schnürch, Andreas. (2026). Oral (poly)peptide delivery: On the emulsifying properties of inverted lipid phases under gastrointestinal conditions.. Journal of controlled release : official journal of the Controlled Release Society, 390, 114508. https://doi.org/10.1016/j.jconrel.2025.114508