pH-sensitive freeze-dried chitosan-polyvinyl pyrrolidone hydrogels as controlled release system for antibiotic delivery

The aim of this study was to develop a pH-sensitive chitosan/polyvinyl pyrr olidone (PVP) based controlled drug release system for antibiotic delivery. The hydrogels were synthesised by crosslinking chitosan and PVP blend with glutaraldehyde to form a semi-interpenetrating polymer network (semi-IPN). The semi-IPN formation was confirmed by Fourier transform infrared spectro scopic (FTIR) analysis. Semi-IPNs, viz, air-dried and freeze-dried, were co mpared for their surface morphology, wettability, swelling properties and p H-dependent swelling. Air- and freeze-dried membranes were also incorporate d with amoxicillin and antibiotic release was studied. Porous freeze-dried hydrogels (pore diameter, 39.20+/-2.66 mu m) exhibited superior pH-dependen t swelling properties over non-porous air-dried hydrogels. A high octane co ntact angle (144.20+/-0.580) of hydrogel was indicative of its hydrophilic nature. Increased swelling of hydrogels, under acidic conditions, was due t o the protonation of a primary amino group on chitosan, as confirmed by FTI R analysis. Freeze-dried membranes released around 73% of the amoxicillin ( 33% by air-dried) in 3 h at pH 1.0 and, thus, had superior drug-release pro perties to air-dried hydrogels. Freeze-dried membranes could serve as poten t candidates for antibiotic delivery in an acidic environment. (C) 2000 Pub lished by Elsevier Science B.V. All rights reserved.