Characterization of the physicochemical interactions between exenatide and two intestinal permeation enhancers: Sodium caprate (C) and salcaprozate sodium (SNAC).

A common approach to tackle the poor intestinal membrane permeability of peptides after oral administration is to formulate them with a permeation enhancer (PE). Increased oral bioavailability for oral peptide candidates has been reported from clinical trials when either salcaprozate sodium (SNAC) or sodium caprate (C) is incorporated in the formulation. However, little is known about how they physically interact with peptides in solution.

Comparison of the effects of the intestinal permeation enhancers, SNAC and sodium caprate (C): Isolated rat intestinal mucosae and sacs.

SNAC and C are intestinal permeation enhancers (PEs) used in formulations of peptides for oral delivery in clinical trials. Our aims were to compare their: (i) mechanism of action in isolated rat intestinal mucosae mounted in Ussing chambers and in non-everted gut sacs, (ii) effects on mucosa integrity in those models and also in in situ intra-jejunal instillations and (iii) interactions with intestinal mucus. SNAC increased the apparent permeability coefficient (P) of the paracellular marker, FITC-dextran 4000 (FD4), across isolated rat gastric mucosae in concentration-dependent fashion, whereas C did not, while both reduced the transepithelial electrical resistance (TEER).

A head-to-head Caco-2 assay comparison of the mechanisms of action of the intestinal permeation enhancers: SNAC and sodium caprate (C).

Salcaprozate sodium (SNAC) and sodium caprate (C) are the two leading intestinal permeation enhancers (PEs) in oral peptide formulations in clinical trials. There is debate over their mechanism of action on intestinal epithelia. The aims were: (i) to compare their effects on the barrier function by measuring transepithelial electrical resistance (TEER), permeability of FITC-4000 (FD4) across Caco-2 monolayers, and on immunohistochemistry of tight junction (TJ)-associated proteins; and (ii) to compare cellular parameters using conventional end-point cytotoxicity assays and quantitative high content analysis (HCA) of multiple sub-lethal parameters in Caco-2 cells.

Oral delivery of diabetes peptides - Comparing standard formulations incorporating functional excipients and nanotechnologies in the translational context.

While some orally delivered diabetes peptides are moving to late development with standard formulations incorporating functional excipients, the demonstration of the value of nanotechnology in clinic is still at an early stage. The goal of this review is to compare these two drug delivery approaches from a physico-chemical and a biopharmaceutical standpoint in an attempt to define how nanotechnology-based products can be differentiated from standard oral dosage forms for oral bioavailability of diabetes peptides. Points to consider in a translational approach are outlined to seize the opportunities offered by a better understanding of both the intestinal barrier and of nano-carriers designed for oral delivery.