A Novel pH-Responsive Super Absorbent Hydrogel Based on Collagen for Ephedrine Controlled Release

In this work, a novel family of pH-responsive polymeric hydrogel based on collagen was prepared for controlled delivery of ephedrine. Acrylic monomers, acrylic acid and itaconic acid were simultaneously graft copolymerized onto collagen backbones by a free radical polymerization technique using ammonium persulfate as initiator and methylene bisacrylamide as a crosslinker. Hydrogel formation was confirmed by FTIR spectroscopy. Thermogravimetric analysis showed that the thermal stabilities of the hydrogels. Results from scanning electron microscopy observation also showed a porous structure with smooth surface morphology of the hydrogel. Swelling profiles obtained clearly indicated that these hydrogels swell slightly in a simulated gastric fluid and strongly in a simulated intestinal fluid. The model drug, ephedrine, was successfully loaded into the hydrogels and in vitro release studies were performed in simulated gastric fluid for the initial 122 min, followed by simulated intestinal fluid until complete dissolution. The release of ephedrine was continued up to 215 min. The release mechanism of the hydrogels was also studied using the Ritger-Peppas model.