Preparation and Evaluation of PEGylated Poly-L-ornithine Complex as a Novel Absorption Enhancer

Abstract

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...

Enhancement Effect of Poly-L-ornithine on the Nasal Absorption of Water-Soluble Macromolecules in Rats

“…5,6) Cationic polymers, such as chitosan and PLA, enhance the in vivo nasal absorption of various water-soluble macromolecules without cytotoxicity to the nasal mucosa. [11][12][13][14][15]17) It has also been reported that these absorption-enhancing effects are dependent on the molecular weight and concentration. Thus, the molecular weight and concentration of polycationic compounds may be involved in their enhancing effect on the absorption of polar macromolecules.…”

“…11,12) In addition, poly-L-arginine (PLA), a cationic polymer, has also been shown to increase the permeability of various hydrophilic macromolecules with-out exerting any cytotoxic effect on the nasal membrane. [13][14][15] All of these permeation enhancers, which both have an enhancing ability and are safe, are cationic polymers. We therefore focused on the cationic polymer poly-L-ornithine (PLO) as a promising permeation enhancer.…”

“…16) Of note, it has been reported that the enhancing effects of chitosan and PLA are dependent on the molecular weight and concentration applied. [11][12][13][14][15]17) This suggests that the enhancement effect of PLO may also be influenced by its molecular weight and concentration, but there were only few reports about its effect of PLO.…”

Synthesis and characterization of innovative poly(lactide-co-glycolide)-(poly-l-ornithine/fucoidan) core–shell nanocarriers by layer-by-layer self-assembly

“…1a) is a biocompatible and low immunogenic polyelectrolyte, 9 within a primary amine side chain and charged when exposed to physiological environment, similar to poly-L-arginine, poly-L-lysine. 10 PLO possesses a wide variety of biological activities, such as enhancing the proliferation, migration and neuronal differentiation/regeneration responses of neural stem/progenitor cells, and also enhances the nasal absorption of hydrophilic macromolecular drugs.…”

“…The detection sensitivity of this kit is higher than other tetrazolium salts. We have performed both dose as well as time dependent inhibition rate, with increasing doses (1,5,10,25, and 50 mg mL…”