Investigation of pH-sensitive galactopyranoside glycol hydrogels as effective vehicles for oral drug delivery

High-loading-capacity pH-sensitive glycol hydrogels were developed using allyl alpha-D-galactopyranoside as a biodegradable and biocompatible carbohydrate. These new pH-sensitive glycol polymers were obtained through the free-radical polymerization of methacrylic acid and allyl alpha-D-galactopyranoside using 1,6-hexanediol diacrylate and 1,6-hexanediol propoxylate diacrylate as crosslinker. The novel sugar-bearing galactopyranoside-based hydrogels were analyzed to test their hydrolytic behavior in vitro, considering their potential application as drug delivery systems. Equilibrium swelling studies were carried out in enzyme-free simulated gastric and intestinal fluids (SGF and SIF; pH 8 and pH 1, respectively). A model drug, olsalazine (an azo derivative of 5-aminosalicylic acid), was entrapped in these gels, and their in vitro release profiles were established separately in SGF and SIF at 37 A degrees C. The swelling and drug release profiles revealed that the amount of drug released and swelling of the hydrogels depended on the methacrylic acid content and the crosslinker type and content.