Effect of ethylene glycol dimethacrylate on swelling and on metformin hydrochloride release behavior of chemically crosslinked pH–sensitive acrylic acid–polyvinyl alcohol hydrogel

Background: The present work objective was to prepare and to observe the effect of ethylene glycol dimethacrylate on swelling and on drug release behavior of pH-sensitive acrylic acid–polyvinyl alcohol hydrogel. Methods: In the present work, pH sensitive acrylic acid–polyvinyl alcohol hydrogels have been prepared by free radical polymerization technique in the presence of benzoyl peroxide as an initiator. Different crosslinker contents were used to observe its effect on swelling and on drug release. Dynamic and equilibrium swelling studies of prepared hydrogels were investigated in USP phosphate buffer solutions of pH 1.2, 5.5, 6.5 and 7.5 with constant ionic strengths. Hydrogels were evaluated for polymer volume fraction, solvent interaction parameter, molecular weight between crosslinks, number of links per polymer chain, diffusion coefficient, sol–gel fraction and porosity. To demonstrate the release pattern of the drug, zero-order, first-order, higuchi and korsmeyer-peppas models were applied. Quality and consistency of hydrogels was examined by FTIR and surface morphology of hydrogels was examined by SEM. Results: Decrease in swelling and in drug release was seen by increasing content of ethylene glycol dimethacrylate. A remarkable high swelling was observed at high pH indicating the potential of this hydrogel for delivery of drugs to intestine. By increasing the concentration of ethylene glycol dimethacrylate, porosity decreased. Order of release was observed first order in all cases and the mechanism was non–fickian diffusion. FTIR confirmed the formation of network. SEM results showed the incorporation of drug. Conclusion: The prepared hydrogels can be suitably used for targeted drug delivery to the intestine.