Oral administration of therapeutic peptides is hindered by poor absorption across the gastrointestinal barrier and extensive degradation by proteolytic enzymes. Here, we investigated the absorption of orally delivered semaglutide, a glucagon-like peptide-1 analog, coformulated with the absorption enhancer sodium N-[8-(2-hydroxybenzoyl) aminocaprylate] (SNAC) in a tablet. In contrast to intestinal absorption usually seen with small molecules, clinical and preclinical dog studies revealed that absorption of semaglutide takes place in the stomach, is confined to an area in close proximity to the tablet surface, and requires coformulation with SNAC. SNAC protects against enzymatic degradation via local buffering actions and only transiently enhances absorption. The mechanism of absorption is shown to be compound specific, transcellular, and without any evidence of effect on tight junctions. These data have implications for understanding how highly efficacious and specific therapeutic peptides could be transformed from injectable to tablet-based oral therapies.

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Biomacromolecules have transformed our capacity to effectively treat diseases; however, their rapid degradation and poor absorption in the gastrointestinal (GI) tract generally limit their administration to parenteral routes. An oral biologic delivery system must aid in both localization and permeation to achieve systemic drug uptake. Inspired by the leopard tortoise’s ability to passively reorient, we developed an ingestible self-orienting millimeter-scale applicator (SOMA) that autonomously positions itself to engage with GI tissue. It then deploys milliposts fabricated from active pharmaceutical ingredients directly through the gastric mucosa while avoiding perforation. We conducted in vivo studies in rats and swine that support the applicator’s safety and, using insulin as a model drug, demonstrated that the SOMA delivers active pharmaceutical ingredient plasma levels comparable to those achieved with subcutaneous millipost administration.

The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin superfamily of cell surface molecules. As a pattern-recognition receptor capable of binding a diverse range of ligands, it is typically expressed at low levels under normal physiological conditions in the majority of tissues. In contrast, the lung exhibits high basal level expression of RAGE localised primarily in alveolar type I (ATI) cells, suggesting a potentially important role for the receptor in maintaining lung homeostasis. Indeed, disruption of RAGE levels has been implicated in the pathogenesis of a variety of pulmonary disorders including cancer and fibrosis. Furthermore, its soluble isoforms, sRAGE, which act as decoy receptors, have been shown to be a useful marker of ATI cell injury. Whilst RAGE undoubtedly plays an important role in the biology of the lung, it remains unclear as to the exact nature of this contribution under both physiological and pathological conditions.

The large number of drug candidates with poor dissolution characteristics seen in the past decade, has fostered interest in so-called "enabling formulations", i.e., formulations which shall make such drugs bio-available. Development of enabling formulations is currently being guided by the following (simplified) hypothesis: If a poorly soluble drug (BCS class II drug) can be transferred into a solubilized state, one can achieve an absorption profile close to that of a soluble drug (BCS class I drug). Thus, formulation development typically endeavors to achieve the most robust solubility enhancement. Here we critically review both common in vitro approaches and experimental data available in literature pertaining to the solubility and permeability of poorly soluble drugs from enabling formulations, and discuss their interplay. Recent in vitro data indicate, that commonly employed surfactants as well as endogenous surfactants present in the intestine, although enhancing drug solubility, mostly hamper drug permeation. Mechanistic studies demonstrate a direct correlation between passive transcellular diffusion and the concentration of molecularly dissolved drug. The latter may be reduced due to partitioning into micelles or other solubilizing carriers, but enhanced in supersaturating formulations. We conclude thus that biopharmaceutical assessment approaches that rely on the amount of molecularly dissolved drug should guide us towards successful enabling formulations.