Comparison of Methods for Encapsulation of Acetyl Salicylic Acid in Polyelectrolyte Capsules Based on Chitosan

Multilayer microcapsules with the encapsulated model drug (acetylsalicylic acid) are formed by the layer-by-layer adsorption of natural polysaccharides, chitosan and sodium carboxymethyl cellulose, onto microparticles of calcium carbonate. Three encapsulation methods are considered: physical adsorption of acetylsalicylic acid in the pores of calcium carbonate microparticles, coprecipitation of an acid with an inorganic template material during its preparation, and incorporation of an acid into hollow capsules by varying the permeability of their shells. To vary the shell permeability, it is proposed to change the polarity of the solvent by introducing 50 vol% ethanol into an aqueous solution. The method has the highest efficiency in encapsulation of acetylsalicylic acid and does not allow the release of acid from the capsules in acidic environments.