Comparison of various generations of superporous hydrogels based on chitosan-acrylamide and in vitro drug release.

The aim of the current research work was to prepare and evaluate different generations of superporous hydrogels (SPH) of acrylamide and chitosan using gas blowing technique and evaluate them for swelling, mechanical properties, FTIR, SEM, XRD, and in vitro drug release. The ingredients used were acrylamide, N,N'-methylene bisacrylamide, chitosan, Pluronic F127, ammonium per sulfate-N,N,N',N'-tetramethylenediamine, and sodium bicarbonate. All ingredients were mixed sequentially with thorough stirring. The effect of different drying conditions on properties of SPH was also evaluated. Ethanol treated batched showed maximum swelling properties due to uniform pores as indicated in SEM studies. Equilibrium swelling time was less than 10 min in all batches. Freeze drying led to lowering of density which is also supported by porosity and void fraction data. Maximum mechanical strength was found in superporous hydrogel interpenetrating networks due to crosslinked polymeric network. 70% drug was released at the end of 2 h, and further the release was sustained till the end of 24 h. In vitro drug release kinetics showed that drug release occurs by diffusion and follows Super Case II transport indicating that mechanism of drug release is not clear. Superporous hydrogel interpenetrating networks can be successfully used as sustained release gastroretentive devices.