Inorganic metal salts as additives in the design of cellulose/arabinogalactan hydrogels for prolonged delivery of simvastatin in simulated bio-fluids

In this study, carboxymethylcellulose and arabinogalactan were used to create an interpenetrating network (IPN) hydrogel system in the presence of AlCl3 alone or in combination with ZnSO4 salts. Ionotropic gelation caused the polymer sol droplets to transform into hydrogel particles in the presence of salts. The impact of salts on hydrogel properties was evaluated in terms of morphology, drug entrapment efficiency, swelling, and drug release kinetics. The cellulose IPN hydrogel particles containing 50% arabinogalactan looked spherical with evidence of surface folding when treated with AlCl3. Surface folding was reduced by an additional treatment with ZnSO4. Following treatment of the IPN particles with dual salts, a maximum drug entrapment efficiency of 88.77% was obtained. Surface erosion, as seen with aluminum-IPN hydrogel particles, was minimized with the use of mixed salts as gelation medium. Furthermore, the use of mixed salts allowed the hydrogel particles to swell and consistently release simvastatin in simulated gastrointestinal fluids for up to 9 h. Thermal and x-ray analyses revealed that the crystallinity of the drug reduced considerably after entrapment in the IPN hydrogel matrix. The infrared spectra analysis did not indicate any evidence of drug polymer interaction. The release of drug from the IPN hydrogel particles followed non-Fickian diffusion mechanism. The dual metallic salts were found to be effective in creating physically stable cellulose-arabinogalactan IPN hydrogel particles for sustained release of simvastatin in a varying pH environment of gastrointestinal tract.