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. 1. Introduction With the advent of new generation drugs, increasing attention is being given to the new methodologies for sustained and better control of drug administration (as discussed by Risbud and Bhonde [1]). Site specific delivery using novel formulation designs would improve local therapy in GI tract, optimize systemic absorption, and minimize premature drug degradation. However, the inability to confine the dosage form in desired area of GIT is one of major difficulties (as discussed by Patel and Amiji [2]). Various technical advancements in fabrication of dosage forms have been explored in this area to retain the dosage form in upper part of gastrointestinal (GI) tract. Small transit time of the dosage form is the main factor responsible for suboptimal absorption making traditional extended release development challenging. A variety of systems such as floating systems, bioadhesive systems, raft systems, expanding systems, swelling systems, and low-density systems have been fabricated as gastroretentive drug delivery (as discussed by Rocca et al. [3] and Bardonnet et al. [4]). Hydrogel polymers are structurally loosely cross-linked networks which have the ability to absorb considerable amounts of