Novel pH-sensitive interpenetrating network hydrogel beads of carboxymethylcellulose-(polyacrylamide-grafted-alginate) for controlled release of ketoprofen: preparation and characterization.

Novel pH-sensitive carboxymethylcellulose-(polyacrylamide-grafted-sodium alginate) interpenetrating network (IPN) hydrogel beads loaded with ketoprofen were prepared using ionotropic gelation and covalent crosslinking method. Polyacrylamide-grafted-sodium alginate (PAAm-g-SA) copolymer was synthesized by free radical polymerization using ammonium persulfate (APS) as free radical initiator under the nitrogen atmosphere followed by hydrolysis using sodium hydroxide. The grafting, alkaline hydrolysis and crosslinking reactions were confirmed by Fourier transform infrared spectroscopy (FTIR). Beads were characterized by differential scanning calorimetric (DSC) analysis, thermogravimetric analysis (TGA), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The mechanical properties of the prepared IPNs were investigated. The erosion was observed with the beads containing only ionic crosslinks whereas it was negligible with the beads containing both ionic and covalent crosslinks. The swelling of the beads and drug release was significantly increased when pH of the medium was changed from acidic to alkaline (P<0.05). The swelling and release data were fitted to an empirical equation to determine the transport mechanism. Drug release followed case II transport mechanism in acidic medium whereas anomalous/non-Fickian transport mechanism was observed in alkaline medium.