Royal College of Surgeons in Ireland
Formulation strategies to improve the efficacy of intestinal permeation enhancers.pdf (2.48 MB)

Formulation strategies to improve the efficacy of intestinal permeation enhancers

Download (2.48 MB)
journal contribution
posted on 2022-06-02, 09:09 authored by Sam MaherSam Maher, David J Brayden
The use of chemical permeation enhancers (PEs) is the most widely tested approach to improve oral absorption of low permeability active agents, as represented by peptides. Several hundred PEs increase intestinal permeability in preclinical bioassays, yet few have progressed to clinical testing and, of those, only incremental increases in oral bioavailability (BA) have been observed. Still, average BA values of ~1% were sufficient for two recent FDA approvals of semaglutide and octreotide oral formulations. PEs are typically screened in static in vitro and ex-vivo models where co-presentation of active agent and PE in high concentrations allows the PE to alter barrier integrity with sufficient contact time to promote flux across the intestinal epithelium. The capacity to maintain high concentrations of co-presented agents at the epithelium is not reached by standard oral dosage forms in the upper GI tract in vivo due to dilution, interference from luminal components, fast intestinal transit, and possible absorption of the PE per se. The PE-based formulations that have been assessed in clinical trials in either immediate-release or enteric-coated solid dosage forms produce low and variable oral BA due to these uncontrollable physiological factors. For PEs to appreciably increase intestinal permeability from oral dosage forms in vivo, strategies must facilitate co-presentation of PE and active agent at the epithelium for a sustained period at the required concentrations. Focusing on peptides as examples of a macromolecule class, we review physiological impediments to optimal luminal presentation, discuss the efficacy of current PE-based oral dosage forms, and suggest strategies that might be used to improve them.


Science Foundation Ireland (SFI)

European Regional Development Fund (ERDF) under grant number 13/RC/2073_2 (SFI CURAM Centre for Medical Devices)



The original article is available at

Published Citation

Maher S, Brayden DJ. Formulation strategies to improve the efficacy of intestinal permeation enhancers. Adv Drug Deliv Rev. 2021;177:113925

Publication Date

18 August 2021

PubMed ID



  • School of Pharmacy and Biomolecular Sciences

Research Area

  • Chemistry and Pharmaceutical Sciences


Elsevier BV


  • Published Version (Version of Record)