EFFECT OF ACID TYPE, ACETIC-ACID AND SODIUM CARBOXYMETHYL CELLULOSE CONCENTRATIONS ON THE FORMATION, MICROMERITIC, DISSOLUTION AND FLOATING PROPERTIES OF THEOPHYLLINE CHITOSAN MICROCAPSULES

An emulsion-phase separation method was devised to prepare chitosan microcapsules containing theophylline and sodium carboxymethyl cellulose (Na CMC). The effect of acid type (acetic acid, ascorbic acid or citric acid) and Na CMC concentration on the formation, micromeritic property, release behavior and floating phenomenon of chitosan microcapsules was studied. Chitosan microcapsules prepared using an acetic acid aqueous solution as a solvent showed a more compact and less porous structure, and exhibited slow release action when compared with other chitosan microcapsules made from ascorbic acid or citric acid. We also found that the greater the amount of Na CMC used, the slower the release and the larger the particle size of the microcapsules obtained. The acetic acid concentration significantly influenced the formation, micromeritic property and release behavior of theophylline chitosan microcapsules containing Na CMC. When the acetic acid concentration was less than 30%, chitosan microcapsules did not form. The particle size of the microcapsules decreased with the increase of acetic acid concentration. Moreover, the higher the acetic acid concentration used the faster was the release rate of microcapsules. The interaction between chitosan and Na CMC in microcapsules caused the formation of a water-insoluble complex, and this complex might significantly affect the formation, micromeritic property and release bahavior of chitosan microcapsules. The acetic acid and Na CMC concentrations also played an important role in controlling the floating property of the microcapsules.