Development of a Non-Aqueous Dispersion to Improve Intestinal Epithelial Flux of Poorly Permeable Macromolecules

Intestinal permeation enhancers (PEs) offer an attractive strategy to enable oral peptide administration. However, optimal presentation of peptide and PE from solid-dosage forms is offset by slow dissolution rates in the small intestine, which reduces the likelihood that the PE can reach the threshold concentration for sufficient permeability enhancement. The purpose of this study was to design a PE-based liquid dispersion that can improve intestinal permeation of macromolecules across Caco-2 monolayers and isolated rat/human intestinal mucosae mounted in Ussing chambers. An enhancer screen in monolayers based on permeability (TEER, P_app [¹⁴C]-mannitol) and cytotoxicity (MTT assay) initially identified methyl 10-hydroxydecanoate (10-OHC₁₀CH₃) as a candidate. 10-OHC₁₀CH₃ (20 mM) increased the P_app of fluorescent dextran of 4 kDa (FD4) (167-fold), 10 kDa (FD10) (429-fold), and 40 kDa (FD40) (520-fold) across monolayers. Blends of 10-OHC₁₀CH₃ with low molecular weight PEGs (0.2-1 kDa) formed liquid dispersions in which enhancement capacity across monolayers of 10-OHC₁₀CH₃ was increased over 10-OHC₁₀CH₃ alone in the order PEG₂₀₀ < PEG₄₀₀ < PEG₆₀₀ < PEG₁₀₀₀. Finally, a 1:5 ratio of 10-OHC₁₀CH₃ (10-20 mM)/PEG₆₀₀ (50-100 mM) increased the P_app of [¹⁴C]-mannitol across rat and human intestinal mucosae. This study highlights the potential future role for non-aqueous, PE-based liquid dispersions in oral delivery of macromolecules.