Why the Same Absorption Trick Helps Some Oral Peptide Drugs but Hurts Others
Permeation enhancers like SNAC (used in oral semaglutide) promote release of hydrophobic peptides but inhibit water-soluble peptides — meaning oral formulations must be carefully matched to each drug.
Quick Facts
What This Study Found
Two permeation enhancers — sodium caprate and SNAC (the technology behind oral semaglutide) — have opposite effects on different types of peptide drugs depending on the peptide's water solubility. In the presence of intestinal bile salts, both enhancers promoted the release of hydrophobic (fat-loving) peptides but inhibited the release of water-soluble peptides from molecular aggregates.
SNAC caused insulin to form more beta-sheet structures, while sodium caprate preserved insulin's alpha-helical and random coil structures. These structural changes matter because they affect whether the peptide drug is active or aggregated when it reaches the intestinal wall. The findings suggest that permeation enhancer selection must be matched to each specific peptide's physical properties.
Key Numbers
2 permeation enhancers (SNAC + sodium caprate) · 4 peptides (octreotide, hexarelin, degarelix, insulin) · taurocholate bile salt · all-atom molecular dynamics simulations
How They Did This
All-atom molecular dynamics simulations modeling interactions between two permeation enhancers (SNAC and sodium caprate), four peptide drugs (octreotide, hexarelin, degarelix, insulin), and intestinal bile salt (taurocholate). Supplemented with experimental FTIR spectroscopy to analyze insulin secondary structure changes in the presence of enhancers.
Why This Research Matters
SNAC is the absorption enhancer that makes oral semaglutide (Rybelsus) possible — the first oral GLP-1 drug. Understanding exactly how SNAC and other enhancers interact with peptide drugs at the molecular level is critical for designing the next generation of oral peptide pills. This study reveals that the same enhancer can help or hinder absorption depending on the peptide's properties, which has major implications for oral formulation development.
The Bigger Picture
Oral semaglutide proved that peptide pills are possible, but scaling that success to other peptide drugs requires understanding why SNAC works for semaglutide specifically. This study reveals that the molecular interactions are highly peptide-specific — the same enhancer that enables oral semaglutide might not work for oral insulin or other peptide drugs. This knowledge is essential for the pharmaceutical industry's push to develop more oral peptide therapeutics.
What This Study Doesn't Tell Us
Computational simulations model molecular interactions but may not fully capture the complexity of the intestinal environment, including mucus layers, epithelial cells, pH gradients, and enzymatic activity. The study tested four peptides, but the principles may not generalize to all peptide drugs. Experimental validation of the predicted release profiles in biological systems would strengthen the conclusions.
Questions This Raises
- ?Can the molecular interaction principles identified here be used to predict which enhancer will work best for a given peptide drug?
- ?Does SNAC's effect on insulin's beta-sheet formation reduce or enhance insulin's biological activity?
- ?Could new permeation enhancers be designed that work universally across both hydrophobic and hydrophilic peptides?
Trust & Context
- Key Stat:
- Opposite effects SNAC and sodium caprate promote hydrophobic peptide release but inhibit water-soluble peptide release — the same enhancer can help or hinder depending on the drug
- Evidence Grade:
- This is a computational study using molecular dynamics simulations with experimental FTIR validation. While it provides valuable molecular-level insights, the findings need biological validation in intestinal absorption models to confirm clinical relevance.
- Study Age:
- Published in 2023 in Nanoscale. Very current, directly relevant to the ongoing race to develop oral peptide drugs building on the success of oral semaglutide.
- Original Title:
- Revealing the interaction between peptide drugs and permeation enhancers in the presence of intestinal bile salts.
- Published In:
- Nanoscale, 15(47), 19180-19195 (2023)
- Authors:
- Hossain, Shakhawath, Kneiszl, Rosita, Larsson, Per
- Database ID:
- RPEP-06960
Evidence Hierarchy
Frequently Asked Questions
What is SNAC and why is it important for oral peptide drugs?
SNAC (sodium N-[8-(2-hydroxybenzoyl) amino] caprylate) is the absorption enhancer that makes oral semaglutide (Rybelsus) possible. It helps the peptide drug cross the stomach lining and enter the bloodstream. This study shows SNAC works differently depending on the peptide's chemical properties — it's not a universal solution for all oral peptide drugs.
Why can't most peptide drugs be taken as pills?
Peptides are destroyed by stomach acid and digestive enzymes, and even if they survive, they're usually too large and polar to cross the intestinal wall. Absorption enhancers like SNAC can help, but this study shows the interaction is peptide-specific — enhancers that work for one peptide may not work for another, making oral formulation a drug-by-drug challenge.
Read More on RethinkPeptides
Cite This Study
https://rethinkpeptides.com/research/RPEP-06960APA
Hossain, Shakhawath; Kneiszl, Rosita; Larsson, Per. (2023). Revealing the interaction between peptide drugs and permeation enhancers in the presence of intestinal bile salts.. Nanoscale, 15(47), 19180-19195. https://doi.org/10.1039/d3nr05571j
MLA
Hossain, Shakhawath, et al. "Revealing the interaction between peptide drugs and permeation enhancers in the presence of intestinal bile salts.." Nanoscale, 2023. https://doi.org/10.1039/d3nr05571j
RethinkPeptides
RethinkPeptides Research Database. "Revealing the interaction between peptide drugs and permeati..." RPEP-06960. Retrieved from https://rethinkpeptides.com/research/hossain-2023-revealing-the-interaction-between
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.