Evaluation and characterization of L-ascorbic acid encapsulated chitosan microspheres

Abstract

Abstract Microencapsulation technique employed to design controlled drug release enhances the safety, efficacy and reliability of the drug therapy. The objective is to regulate drug release rate in order to provide relief to patients from following a dosage regime. These control release methods help in enhancing the stability, bioavailability, and half-life of drug. The controlled and localized release reduces the risks of manifestation of any side-effects. There are many methods for preparation of microspheres with wide range of size depending on the application requirement. The aim of the present study has been evaluation and characterization of microspheres by water-in-oil emulsification method using chitosan as polymer and glutaraldehyde as cross-linking agent. Chitosan is chosen as the polymer for this study. It is a natural, non-toxic, biocompatible and biodegradable polymer with a great potential for pharmaceutical and biomedical applications. Glutaraldehyde is used as cross-linking agent due to its commercial availability and low cost. L-ascorbic acid (vitamin C) is selected for this study as it a very important vitamin with many emerging applications, especially in cancer treatment. L-ascorbic acid encapsulated chitosan microspheres were prepared by dropping the chitosan-drug solution in the light liquid paraffin and span-80 emulsion, followed by periodical addition of glutaraldehyde. The system was subjected to constant stirring at high rpm. The effect of varying polymer-drug ratio on the preparation and properties of microspheres were studied. Microspheres were characterized by their percentage yield, particle size and morphology, percentage swelling index, drug encapsulation efficiency, and in vitro release. Blank chitosan microspheres were also prepared by the same method, minus the drug. The effect of varying polymer concentration was studied. These microspheres were also characterized by their percentage yield, particle size and morphology. Blank microspheres were loaded with L-ascorbic acid on the basis of their percent swelling index under different pH conditions. Their drug encapsulation efficiency and in vitro release were studied. The drug loading by incubation method was less than the loading in cross-linking method. The polymer to drug ratio affects the drug yield, particle size and morphology, encapsulation efficiency and drug release profile of microspheres. After studying various parameters it was examined that B6 was the best batch having polymer to drug ratio 2.5:1 i.e. 2.5% (w/v) chitosan and 1% (w/v) L-ascorbic acid.