Oral gingival delivery systems from chitosan blends with hydrophilic polymers

Chitosan blends with hydrophilic polymers including polyvinylalcohol (PVA), polyethyleneoxide (PEO) and polyvinylpyrrolidone (PVP), were investigated as candidates for oral gingival delivery systems. The bioavailabilty conferred by the chitosan blend delivery systems, as concluded from dog studies, was shown to be comparable to that based on chitosan alone, especially for those blends involving high molecular weight hydrophilic polymers. Results from differential scanning calorimetry and dynamic mechanical thermal analysis, Fourier transform infrared spectroscopy and tensile testing, indicated that the chitosan/PEO and chitosan/PVP blends showed evidence of miscibility in all blend ratios studied, while the chitosan/PVA blend only showed evidence of interaction for the (50:50) and (80:20) blends, but not for the (20:80) blend. However, even a phase separated system may show interesting and exploitable properties, as evidenced by the tensile testing data for the high molecular weight PVA blend (20:80). The study also indicated that chitosan blends were superior in other properties compared to chitosan alone. These included improved comfort and reduced irritation, ease of processing, improved film quality, improved flexibility, and enhanced dissolution. Blends of chitosan with different hydrophilic polymers could thus be promising candidates for formulation in oral mucosal delivery systems. (C) 2002 Elsevier Science B.V. All rights reserved.