Phosphated crosslinked pectin as a potential excipient for specific drug delivery: preparation and physicochemical characterization

Pectin was chemically modified with different amounts of trisodium trimetaphosphate (STMP) in aqueous solution (pH = 12), thereby giving a material with reduced water solubility. The physiochemical characterization of this new material was carried out through Fourier transform infrared and thermogravimetric analyses. Phosphated pectin (Pect-STMP) together with prebiotic (oligosaccharide) were incorporated into an aqueous dispersion of polymethacrylate (Eudragit(R) RS 30 D) in order to obtain free films using a casting process (50 degrees C) on a Teflon plate. The free films were evaluated using water vapour transmission, average swelling index in simulated gastric fluid (SGF) and simulated intestinal fluid, scanning electron microscopy and a diffusion study with theophylline in buffer solution with and without pectinolytic enzyme. The results suggest that the new material can be used in the coating process for oral solid-reservoir systems, to prevent the premature release of drugs in SGF (pH = 1.2). Furthermore, the presence of both Pect-STMP and oligosaccharide favours the specific degradation of the pellicle by the action of the enzymes produced by colonic microflora. The material obtained in this work has the potential to be applied in devices for drug delivery in the colon, making possible modified release of drugs. Nevertheless, subsequent colon-specific experiments in vivo need to be carried out in order to confirm the possible application of this new material. (C) 2009 Society of Chemical Industry