Polycationic compounds, such as poly-L-arginine and poly-L-ornithine (PLO), enhance the nasal absorption of hydrophilic macromolecular drugs. However, the bio availability corresponding to the dose of these enhancers has not been obtained in an open system study, where an administered solution is transferred to the pharynx because they do not exhibit mucoadhesion/retention in the nasal cavity. In this study, we prepared PEGylated-poly-L-ornithine (PEG-PLO) and investigated the effects of PEGylation on in vitro adhesion/retention properties, permeation enhancement efficiency, and cytotoxicity. PEG-PLO bearing 3-4 polyethylene glycol (PEG) chains per PLO molecule was more retentive than unmodified PLO on an inclined plate. The permeability of a model drug, FD-4, across Caco-2 cell sheets was enhanced by PEG-PLO as well as by PLO. PLO showed cytotoxicity at high concentrations, whereas PEG-PLO did not decrease cell viability, even above the concentration giving a sufficient enhancement effect. These findings suggest that PEGylation of polycationic absorption enhancers improves their adhesion/retention and decreases their cytotoxicity, which may lead to enhancers with greater utility.Key words poly-L-ornithine (PLO); polyethylene glycol (PEG); permeation enhancer Bioactive peptides, such as insulin, teriparatide, liraglutide, and somatropin, have been used widely as therapeutic drugs because of their intrinsic and effective activities, however, they have poor permeability across the epithelium because they are hydrophilic macromolecules. Orally administered peptides are often inactivated in the gastrointestinal tract, and thus peptides are usually administered as injectable formulations. However, injection can result in poor compliance because it is painful and burdensome. 1) Therefore, alternative routes of administration are required.The nasal mucosa has a large surface area for absorption because of its villus structure. Drugs absorbed across the nasal mucosa avoid the hepatic first pass effect because of the abundant vasculature under the nasal mucosa.2) The intranasal route is effective for absorbing high molecular weight drugs 3) and is usually not painful. Therefore, intranasal administration is an important alternative route to injection for peptides and proteins.Polycationic compounds, such as poly-L-arginine (PLA), poly-L-lysine, and poly-L-ornithine (PLO), enhance the transmucosal absorption of hydrophilic macromolecules.4,5) PLA enhances the paracellular permeability of rabbit nasal mucosa and Caco-2 cell sheets reversibly.6,7) The absorption of hydrophilic macromolecules across the nasal mucosa in rats is also increased by co-administration with PLA. 8) PLA enhances the permeability by altering the localization of tight junction proteins from the cell-cell junction to the intracellular space without causing cytotoxicity. 9) Therefore, polycationic absorption enhancers are useful in developing efficient transmucosal drug delivery systems.Nevertheless, it is difficult to increase the bioavailability of dr...

PLA induced the transient internalization of TJ proteins in cell-cell junctions via clathrin-mediated endocytosis, subsequently increasing the permeability of the Caco-2 cell monolayer to FD-4 via a paracellular route.

We report a novel smart micellar system utilising a phenylboronic acid (PBA) derivative whose viscosity increases on adding diol compounds such as sugar or sugar alcohol.

We investigated whether poly-l-arginine (PLA) enhances the paracellular permeability of the Caco-2 monolayer to hydrophilic macromolecules and clarified the disposition of tight junction (TJ) proteins. The transepithelial electrical resistance (TEER) and fluorescein isothiocyanate (FITC)-dextran (FD-4) permeation were determined after treatment with PLA. TJ proteins were visualized using immunofluorescence microscopy after PLA exposure and depletion, and their expression levels were determined. The barrier function of TJs was also evaluated by measuring the alterations in the TEER and in the localization of TJ proteins. PLA induced an increase in hydrophilic macromolecule, FD-4, permeation through Caco-2 cell monolayers and a decrease in the TEER in a concentration-dependent manner, without any significant impact on the cell viability. This increased paracellular permeability induced by PLA was found to be internalized of claudin-4, ZO-1, tricellulin and mainly occludin from cell-cell junction to the subcellular space. ZO-1 appeared to play an important role in the reconstitution of TJ strand structures following PLA depletion. These results indicate that the PLA led to the internalization of TJ proteins to the subcellular space, subsequently increasing the permeability of the Caco-2 cell monolayer to FD-4 via a paracellular route.

No abstract

Herein, we report anomalous glucose (Glc)-responsive gelation/solation in 3-aminophenylboronic acid-modified hyaluronic acid.

We have already reported that poly-l-arginine (PLA) remarkably enhanced the in vivo nasal absorption of hydrophilic macromolecules without producing any significant epithelial damage in rats. In the present study, we examined whether PLA could enhance the absorption of a model hydrophilic macromolecule, fluorescein isothiocyanate-dextran (FD-4), across the intestinal mucosa, as well as the nasal mucosa, by an in situ closed-loop method using the rat intestine. PLA was found to enhance the intestinal absorption of FD-4 in a concentration-dependent manner within the concentrations investigated in this study, but segment-specific differences were found to be associated with this effect (ileum>jejunum>duodenum≧colon). The factors responsible for the segment-specific differences were also investigated by intestinal absorption studies using aprotinin, a trypsin inhibitor, and an analysis of the expression of occludin, a tight junction protein. In the small intestine, the differences in the effect of PLA on the absorption of FD-4 may be related to the enzymatic degradation of PLA. In the colon, the reduced effect of PLA on the absorption of FD-4 may be related to the smaller surface area for absorption and the higher expression of occludin compared with other segments.Key words poly-l-arginine; intestinal absorption; enhancer; fluorescein isothiocyanate-dextran (FD-4); occludin; aprotininWe have already reported that poly-l-arginine (PLA), a polycation, remarkably enhanced the in vivo nasal absorption of hydrophilic macromolecules in rats and increased their in vitro permeation across the rabbit nasal epithelium without producing any significant epithelial damage. [1][2][3][4][5] This effect is caused by the opening of tight junctions (TJ) in the epithelial cells. PLA plays an important role in opening the TJ in these cells, and the reaction induced by PLA appears to be reversible.4,6) Therefore, PLA is considered to be promising as an absorption enhancer for transnasal drug delivery. Although some studies have examined whether PLA can also enhance the absorption of hydrophilic macromolecules across the nasal epithelium, conjunctiva, alveolar epithelium, and Caco-2 cell sheets, [7][8][9][10] there have been no studies looking at PLA᾿s absorption enhancing effect across the intestinal mucosa. The intestinal mucosa is an important tissue particularly for the absorption of orally administered drugs.The intestinal absorption of hydrophilic macromolecules is well known to be typically very poor.11) The small intestine has an extensive surface area for absorption, but various digestive enzymes exist in the gastrointestinal tract. The property of intestinal mucosa differs from that of the nasal mucosa in some respects. Therefore, in order to improve the absorption of hydrophilic macromolecules, various strategies such as the use of absorption enhancers, protease inhibitors and chemical modification have been examined in the intestinal mucosa as well as the nasal mucosa. [12][13][14][15] It was recently reported that the TJ ba...

We reported that the introduction of polyethylene glycol (PEG) to poly-l-ornithine (PLO), which is an homopolymeric basic amino acid having absorption-enhancement ability, prolonged retention time in an in vitro inclined plate test, probably due to an increase in viscosity caused by PEGylation. The aim of the present study is to investigate whether the introduction of PEG chains to PLO improves intranasal retention and transnasal absorption in vivo. We performed intranasal administration experiments using PLO and PEG-PLO with a model drug, fluorescein isothiocyanate dextran (FD-4), in rats under closed and open systems. In the open system, transition of plasma FD-4 concentration after co-administration with unmodified PLO was low, and the area under the plasma concentration-time curve (AUC) decreased to about 60% of that in the closed system. In contrast, the AUC after co-administration with PEG-PLO in the open system was about 90% of that in the closed system, and the transition of plasma FD-4 concentration and FD-4 absorption profile were similar to those of the closed system. These findings indicate that introducing PEG chains to homopolymeric basic amino acids (HPBAAs) is a very useful method for developing a functional absorption enhancer that can exhibit an efficient in vivo absorption-enhancing effect.