In this study, sustained release superabsorbent polymer (SAP) particles were prepared to
minimize the local irritating effect of risedronate sodium. Formulations were prepared by free radical
polymerization of various combinations of 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA),
and chitosan (CTS) by using ethylene glycol dimethacrylate (EGDMA) as crosslinker, potassium persulfate
as initiator, and N,N,N,N-tetramethylethylene diamine as activator. Polymerization was confirmed
by Fourier transform infrared spectroscopy. For dynamic swelling studies, buffer solutions of
various pH were utilized. The IA content of formulation and pH of surrounding media were found in
direct relationship with swelling capability. Gel fraction and porosity were also determined and a direct relationship was
found with monomers/polymer contents. Formulations were successfully loaded with risedronate sodium and loading efficiency
was found to be dependent on IA and CTS contents. Drug release study was performed both in acidic and basic
media and found dependent on pH. Release data were analyzed by various kinetic models and mechanism of drug release
was best explained by zero order kinetics at acidic and Higuchi kinetics at basic environment. The n value of Korsemeyer-
Peppas model showed that drug release followed non-Fickian release pattern.
Keywords: 2-hydroxyethyl methacrylate, itaconic acid, Chitosan, risedronate sodium, superabsorbent polymer.
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