Investigation of dynamic release of vitamin B2 from calcium alginate/chitosan multilayered beads:: Part II

In the present work, multilayered beads, prepared by complex coacervation of calcium alginate and chitosan, followed by sequential coating with chitosan and calcium alginate have been studied for the release of model drug vitamin B-2 in the media of varying pH at 37 degrees C. It has been observed that the beads demonstrated nearly 54 +/- 4% drug release in first 3 h in the artificial gastric fluid (pH 1.0) while remaining drug is released in the simulating intestinal fluid of pH 7.4 in 6 h. The stability of the beads and their drug releasing capacity has been studied as a function of composition of outermost alginate layer and its extent of crosslinking. Finally, to incorporate in vivo gastrointestinal (GI) conditions in the study, the release study was also carried out by 'flow through diffusion cell (FTDC) method'. The beads demonstrated slower release in FTDC as compared to the tradition dissolution test. The nature of filler particles also affected the release profiles in FTDC method. The various diffusion coefficients have also been evaluated. (c) 2006 Elsevier B.V. All rights reserved.