The purpose of the present study was to solve the problem of the fast release of the water soluble drug linked to polysaccharides ion-exchange microspheres, which display a high degree of swelling. Dextran ion-exchange microspheres (Dm = 80 μm) loaded with two different water soluble drugs (Tetracycline HCl, Propranolol HCl), were included in cellulose acetate butyrate (CAB) microcapsules. Spherical CAB microcapsules were obtained by oil in water (o/w) solvent evaporation method in the presence of an inert solvent as cyclohexane (CyH) or n-hexane (N-Hex), and different excipients (Phospholipon, Tween, Span, Eudragit RS 100). Chloroform was found to be the best solvent for the preparation of the microcapsules. Also, the sphericity as well as the porosity of the microcapsules was controlled by the presence of an inert solvent. The final concentration of the drug in CAB microparticles was up to 25 % (w/w). The key factors for the successful preparation were also the viscosity of the polymer, while the wettability of the resulted microcapsules, the temperature of the preparation, and the porosity have modulated the release of the drug. The higher is the amount of encapsulated microspheres the thinner is the CAB wall between the compartments created by their incorporation. When these microspheres come in contact with the release medium, the pressure created by their swelling breaks the polymer film and the drug starts to be released. The more drug is released in phosphate buffer the higher is the swelling degree of the encapsulated ion exchange resins and the force created by their supplementary swelling will break the more resistants walls. In this way a self-propelled drug release is achieved, until almost all drug was eliberated. In conclusion, the results here presented, clearly demonstrated that dextran cation exchange microspheres, pre-loaded with drugs, were successfully encapsulated in CAB microcapsules, in order to modulate the release of the drugs from the final microcapsules.
Cellulose acetate butyrate microcapsules containing dextran ion-exchange resins as self-propelled drug release system
ESPOSITO, Elisabetta;CORTESI, Rita;NASTRUZZI, Claudio;MENEGATTI, Enea
2005
Abstract
The purpose of the present study was to solve the problem of the fast release of the water soluble drug linked to polysaccharides ion-exchange microspheres, which display a high degree of swelling. Dextran ion-exchange microspheres (Dm = 80 μm) loaded with two different water soluble drugs (Tetracycline HCl, Propranolol HCl), were included in cellulose acetate butyrate (CAB) microcapsules. Spherical CAB microcapsules were obtained by oil in water (o/w) solvent evaporation method in the presence of an inert solvent as cyclohexane (CyH) or n-hexane (N-Hex), and different excipients (Phospholipon, Tween, Span, Eudragit RS 100). Chloroform was found to be the best solvent for the preparation of the microcapsules. Also, the sphericity as well as the porosity of the microcapsules was controlled by the presence of an inert solvent. The final concentration of the drug in CAB microparticles was up to 25 % (w/w). The key factors for the successful preparation were also the viscosity of the polymer, while the wettability of the resulted microcapsules, the temperature of the preparation, and the porosity have modulated the release of the drug. The higher is the amount of encapsulated microspheres the thinner is the CAB wall between the compartments created by their incorporation. When these microspheres come in contact with the release medium, the pressure created by their swelling breaks the polymer film and the drug starts to be released. The more drug is released in phosphate buffer the higher is the swelling degree of the encapsulated ion exchange resins and the force created by their supplementary swelling will break the more resistants walls. In this way a self-propelled drug release is achieved, until almost all drug was eliberated. In conclusion, the results here presented, clearly demonstrated that dextran cation exchange microspheres, pre-loaded with drugs, were successfully encapsulated in CAB microcapsules, in order to modulate the release of the drugs from the final microcapsules.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
