Release characteristics of ascorbic acid encapsulated chitosan treated alginate microspheres

Abstract

Abstract Novel drug delivery systems have several advantages over conventional multi dose therapy. Much research effort in developing novel drug delivery system has been focused on controlled release and sustained release dosage forms. Now considerable efforts are being made to deliver the drug in such a manner so as to get optimum benefits. There are various approaches in delivering a therapeutic substance to the target site in a sustained controlled release fashion. One such approach is using microspheres as carriers for drugs. The aim of the present work was formulation and evaluation of microspheres by ionotropic gelation method using sodium alginate as polymer and CaCl2 as cross-linking agent. Chitosan and sodium alginate as a natural biodegradable polymer provides good barrier to the core material from the surrounding environment as well as very effective in controlled drug delivery system. It also helped in retaining L-ascorbic acid for longer duration in human body. Ionotropic gelation method is an effective method where harsh and harmful chemicals are not used and hence safer for human consumption. The control of various manufacturing parameters plays a very important role in obtaining microspheres of good sphericity, high yield and high drug encapsulation. L-ascorbic acid microspheres were prepared by dropping the drug containing solution of sodium alginate. The droplets instantaneously formed gelled spheres by the ionotropic gelation method. The microspheres were characterized by their percentage yield, morphology, particle size, swelling studies, encapsulation efficiency and in vitro drug release rate. Release studies were done in buffer (pH 1.2) and subsequently in buffer (pH 6.8). The release of drug from microspheres was greatly affected by drug concentration, polymer concentration, CaCl2 concentration, stirring time and stirring speed. After studying various parameters it was examined that B2 and B9 were the best having concentration of sodium alginate 2% at 100 rpm for 30 minutes. Entrapment efficiency and in vitro release was better observed in chitosan coated microspheres as shown in batch no. 9 and batch no. 4 with equal concentration but batch no. 9 was chitosan coated and batch no. 4 was sodium alginate microspheres.