Fabrication and In vitro Evaluation of Carbopol/Polyvinyl Alcohol-based pH-sensitive Hydrogels for Controlled Drug Delivery

Background:: Diclofenac sodium has a short half-life (about 1.5 hours), requiring repeated administration, and as a result, serious complications, such as GI bleeding, peptic ulcer, and kidney and liver dysfunction, are generated. Hence, a sustained/controlled drug delivery system is needed to overcome the complications caused by the administration of diclofenac sodium. Aims:: This study aimed to fabricate and evaluate carbopol/polyvinyl alcohol-based pH-sensitive hydrogels for controlled drug delivery. Objective:: pH-sensitive carbopol/polyvinyl alcohol graft-poly(acrylic acid) hydrogels (Cp/PVA-g-PAa hydrogels) were developed for the controlled delivery of diclofenac sodium. Methods:: The combination of carbopol/polyvinyl alcohol, acrylic acid, and ethylene glycol dimethacrylate was used as polymer, monomer, and cross-linker, respectively. The effects of the formulation’s composition on porosity, swelling index, and release pattern of diclofenac sodium from the developed hydrogels were investigated. Results:: An increase in porosity and swelling was observed with the increasing amounts of carbopol and acrylic acid, whereas polyvinyl alcohol showed the opposite effect. Due to the formation of a highly viscous system, the drug release decreased with the increasing concentrations of carbopol and polyvinyl alcohol while increased with increasing acrylic acid concentration. The pH-responsive properties of the fabricated hydrogels were demonstrated by dynamic swelling and drug release studies at three different pH values. Higher dynamic swelling and diclofenac sodium (model drug) release were found at high pH values compared to low pH values, i.e., pH 7.4 > 4.6 > 1.2, respectively. Cytotoxicity studies reported no toxic effect of the prepared hydrogels, thus indicating that the prepared hydrogels are safe to be used on clinical basis. Conclusion:: The prepared carbopol/polyvinyl alcohol crosslinked hydrogel can be used as a promising carrier for the controlled release of drugs.