Formulation Strategies to Make Intestinal Permeation Enhancers Work for Oral Peptide Drugs | Research

The takeaway

Review of formulation strategies that optimize intestinal permeation enhancers for oral peptide delivery, covering how to maximize enhancer-peptide co-localization and overcome the gastrointestinal barriers that limit oral peptide absorption.

Formulation is the bottleneck
Oral peptides are possible (Rybelsus proved it) but ~1% bioavailability means 99% of the drug is wasted. Better formulations could transform this ratio

What the researchers found

Formulation strategies including enteric coatings, nanoparticle co-encapsulation, mucoadhesive formulations, and timed-release systems optimize intestinal permeation enhancer efficacy for oral peptide delivery.

Why it matters

Oral semaglutide (Rybelsus) proved oral peptides are possible, but its bioavailability is still low (~1%). Better formulation strategies could dramatically improve oral peptide drug absorption and efficacy.

The numbers in context

~1% BA; FDA approvals: oral semaglutide, oral octreotide; challenges: dilution, transit, luminal interference

How the study worked

Narrative review of formulation approaches for optimizing IPE-peptide co-delivery and overcoming GI barriers.

Who was studied

N/A (review of oral peptide delivery research and clinical trials)

What this study cannot tell us

Review article. Most strategies preclinical. No single formulation approach solves all challenges. Patient-to-patient variability in GI conditions complicates universal formulation design.

How to read the evidence

Not applicable (formulation science review).

When this study was published

Published 2021. Oral peptide formulation continues advancing rapidly.

The bigger picture

Oral peptide delivery is transitioning from impossible to practical. Formulation science is the remaining bottleneck — turning proof-of-concept (Rybelsus) into high-bioavailability products.

Questions still open

Can formulation alone increase oral peptide bioavailability from 1% to >10%?
Which IPE-formulation combination shows the most promise for clinical use?
Would combination formulation strategies provide additive absorption benefits?

Common questions

Why is oral semaglutide bioavailability only ~1%?

Even with SNAC permeation enhancer, 99% of oral semaglutide is destroyed or not absorbed. The enhancer and peptide must arrive at the same gut location simultaneously, the stomach must be empty, and the absorption window is narrow. Better formulations aim to solve these challenges.

What is a permeation enhancer?

Permeation enhancers are molecules that temporarily open the tight junctions between gut lining cells, creating brief windows for peptide drugs to pass through. The challenge is getting the enhancer and drug to the same spot at the right time — which is where formulation strategy comes in.

Read the original research

Formulation strategies to improve the efficacy of intestinal permeation enhancers.

Advanced drug delivery reviews, 177, 113925

View on PubMed ↗Publisher’s paper ↗

Citation

Maher, Sam; Brayden, David J. (2021). Formulation strategies to improve the efficacy of intestinal permeation enhancers.. Advanced drug delivery reviews, 177, 113925. https://doi.org/10.1016/j.addr.2021.113925