Studies on pectin as a potential carrier in colonic drug delivery

Abstract

The feasibility of new microencapsulated cores for colon specific delivery of drug was studied using, diclofenac potassium (DP), a NSAID, as a model anti-inflammatory drug. The polysaccharide pectin was reacted with sodium alginate in the presence of calcium chloride to form microcapsules with a polyelectrolyte complex membrane. Microcapsules were evaluated for physical characteristics such as size, shape, surface features, strength and flexibility of the membrane, viscosity and encapsulation efficiency. Microcapsules were also evaluated for in vitro study containing rat caecal content and ulcer study. It was found that pectin-alginate microcapsules, prepared with 0.5% w/v of the encapsulating polymer and 2.5 % w/v of sodium alginate were best suited for the colon specific delivery. These microcapsules were further modified to attain a higher specificity. The key factor found to affect membrane formation was the pectin molecular weight. These results indicate that the microcapsules with the greatest promise for success are those produced with high and low molecular weight polymers. Increasing the alginate concentration from 1.5 to 2.5% w/v further retarded the drug release. Good colon specificity was achieved at 2.5% w/v concentration of sodium alginate for pectin microcapsules. Selected formulations were also studied for ulcer study. Pure DP showed ulcer index of 30.8 and whereas no ulcer was found in the case of microcapsules.