Mucoadhesive Polymers for Oral Transmucosal Drug Delivery: A Review

Abstract

Abstract:The oral mucosa offers an interesting site for the application of dosage forms that release drugs within/throughout the oral mucosa, by assuring a high drug bioavailability for topic and systemic effects. However, the relative permeability of the oral mucosa and the washing effect related to the oral fluids and mechanical stresses must be considered in the formulation of oral dosage forms. Since a sustained drug release can be guaranteed only if dosage forms remain in contact with the oral site of absorption/application for a prolonged time, the development of mucoadhesive dosage forms is mandatory. The mucoadhesion is a complex phenomenon and the mucoadhesive bond consists of two different parts, the mucoadhesive polymers and the mucous substrate. In addition to factors related to the oral mucosa and oral environment features, the physical-chemical characteristics of mucoadhesive polymers must be also considered as factors influencing the mucoadhesive bonds. While it is not possible to modify the mucosal features or it is possible to modify or inhibit only in part certain mucosal processes, the knowledge of polymer properties influencing mucoadhesive bonds allows to modify or to control these properties in developing increasingly effective mucoadhesive systems. The aims of this review are to discuss the several mechanisms and factors behind the phenomenon of mucoadhesion with particular reference to the features of the oral environment, oral mucosa, and polymeric compounds influencing mucoadhesion process. Finally, a brief mention to the main mucoadhesive dosage forms designed for oral transmucosal drug delivery is made.

Bioadhesive drug delivery system of diltiazem hydrochloride for improved bioavailability in cardiac therapy

“…Although the marked increase in surface area during swelling can promote drug release, the increase in diffusion path length of the drug may paradoxically delay the release. In addition, the thick gel layer formed on the swollen film surface is capable of preventing matrix disintegration and controlling additional water penetration [15].…”

“…The buccal mucosa is one of the most suitable sites for MDDS [2,[4][5][6][7][8]. Attempts have been made to formulate various mucoadhesive devices including tablets, films, patches, disks, strips, ointments and gels [9][10][11][12][13][14][15][16]. Buccal film may be preferred over adhesive tablet in terms of flexibility and comfort.…”

Programming of Influenza Vaccine Broadness and Persistence by Mucoadhesive Polymer-Based Adjuvant Systems

“…These interactions are thought to be a result of the hydrogen bonds between g-PGA and the proton-accepting groups within the mucus glycoprotein. It was concluded that the mucoadhesive polymer could interact with the mucin molecule by physical chain entanglements followed by hydrogen bond formation with the sugar residues on the oligosaccharide chains, forming a strengthened gel network, thus allowing the polymer to remain adhesive for extended periods of time (38,39). As the polymer would be in an expanded uncoiled state at the pH of the medium (6.2) due to the electrostatic repulsion arising from the ionized functional groups, the polymer would be more susceptible to mechanical chain entanglement and secondary interactions with the mucus glycoprotein.…”

“…These experimental results suggest that g-PGA increased the residence time of the codelivered OVA Ags in the mucus layer and acted as a controlled-release reservoir for the nasal epithelial cells. We speculated that g-PGA could interact with mucin molecules through physical chain entanglements and form hydrogen bonds with the sugar residues on the oligosaccharide chains (38,39). Because g-PGA is in the expanded uncoiled state at the pH of the nasal secretions (pH 6.0-6.5), the electrostatic repulsion arising from the ionized functional groups renders g-PGA more susceptible to mechanical chain entanglement and secondary interactions with the mucous glycoprotein (40).…”

Buccal Transmucosal Delivery System of Enalapril for Improved Cardiac Drug Delivery: Preparation and Characterization

“…Mucoadhesive polymers are used for the formulation of TMDDS. These polymers generally are the polymers and their different grades with high molecular weight, high viscosity, greater flexibility and optimum chain length [9][10][11][12][13].…”