Gum Acacia and Methacrylic Acid Hydrogels: Preparation and Swelling Characteristics

pH sensitive hydrogels of gum acacia (GA) and poly(methacrylic acid)(PMA) were synthesized by ceric ion initiated graft copolymerization in aqueous medium in the presence of varying amount of N, N–methylene bisacrylamide as a crosslinking agent. The copolymers were characterized by FTIR spectroscopy and swelling measurement. These hydrogels were used for the in vitro drug release studies using paracetamol as the model drug. The drug release was studied as a function of pH. The release was much slower in first 3 hrs at pH 1.2 for all the hydrogels which may attribute to the matrix compaction and stabilization through hydrogen bonding at lower pH. At pH 7.4 the amount of drug release was 60 – 70% in 12 hr. The kinetic study shows that the release of the drug from hydrogels was probably controlled by the swelling and relaxation of the polymers indication a super case II transport. These results indicate that the hydrogels may be useful to overcome the harsh environment of the stomach and can be used as excipient in colon targeting matrices.