Chemical cross-linking approach for prolonging diclofenac sodium release from pectin-based delivery system

To overcome the instability of pectin-Ca²⁺ gels based oral colon-specific drug delivery system (OCDDS) in the upper gastrointestinal tract, the chemical cross-linked pectin carriers were prepared by adding succinic anhydride and glutaric dialdehyde as the cross-linking reagents. The diclofenac sodium was employed as the water-soluble drug model to calculate the controlled release properties. The encapsulation efficiency and loading efficiency were measured and the sample PG1 shows the best efficiency of 78.81% and 7.78%, respectively. The simulative release rate was estimated and the cumulative release rate of sample PG₁ reached to a maximum of 3.04, 3.66 and 79.43% in SGF, SSIF and SCF. The release data was employed to fit the First order, Higuchi, Bhaskar, and Ritger-peppas model and the goodness of the fit was calculated by the regression coefficient. The succinic anhydride and glutaric dialdehyde cross-linked pectin were characterized by FTIR to prove the cross-linking reaction. In addition, FE-SEM characterization of sample PG1 indicated the rally microsphere with smooth surface. The sample PG1 after the digestion was also characterized by the FE-SEM, and irregularly structure was obtained.