Natural polymers have great advantages because they have good biocompatibility, specific degradation and the feasibility to incorporate drugs into their matrices. Amongst the natural polymers, alginate has been used by many workers as a matrix for the controlled release of drugs [1, 2]. It has an ability to cause a bioadhesion with mucosal membranes. Drug delivery in the oral mucosa has many advantages for drugs such as local anaesthetics. However, this site of the oral cavity is subjected to the influence of the salivation process, that can remove the remanent dosage form from the application site. Therefore, the addition of a bioadhesive to the bead formulation could avoid this removing effect. The most commonly used technique for carrying drugs in an alginate matrix is by extruding droplets of alginate drug solution or dispersion into a calcium chloride bath. Gelation occurs by an ionic interaction between the calcium ions and the carboxylate anion of G-G blocks as calcium ions diffuse from the external source into the droplet. An alternative to these techniques is the emulsification method, which allows the encapsulation of the drug in small beads. Bead formation through emulsion techniques has not been adequately investigated with bioadhesive polymers. An emulsion of an alginate aqueous solution in oil can be added to CaCl2 solution, and thereby leads to bead formation. However, particle size cannot be easily controlled and the beads tend to coagulate into large masses before hardening properly. In the present study, the gelation of alginate-Chitosan (CH) and alginate-Gantrez® solution is achieved through the emulsification of this solution with the lipophilic phase. In a first stage, a morphological study by SEM has been realized, in order to determine the presence or absence of bead aggregates, and their shape parameters.

ELABORATION OF ALGINATE MICROSPHERES BY EMULSIFICATION-IONOTROPIC GELATION TECHNIQUE CONTAINING BIOADHESIVE POLYMERS. A MORPHOLOGICAL STUDY OF THE SYSTEMS

FINI, ADAMO
2006

Abstract

Natural polymers have great advantages because they have good biocompatibility, specific degradation and the feasibility to incorporate drugs into their matrices. Amongst the natural polymers, alginate has been used by many workers as a matrix for the controlled release of drugs [1, 2]. It has an ability to cause a bioadhesion with mucosal membranes. Drug delivery in the oral mucosa has many advantages for drugs such as local anaesthetics. However, this site of the oral cavity is subjected to the influence of the salivation process, that can remove the remanent dosage form from the application site. Therefore, the addition of a bioadhesive to the bead formulation could avoid this removing effect. The most commonly used technique for carrying drugs in an alginate matrix is by extruding droplets of alginate drug solution or dispersion into a calcium chloride bath. Gelation occurs by an ionic interaction between the calcium ions and the carboxylate anion of G-G blocks as calcium ions diffuse from the external source into the droplet. An alternative to these techniques is the emulsification method, which allows the encapsulation of the drug in small beads. Bead formation through emulsion techniques has not been adequately investigated with bioadhesive polymers. An emulsion of an alginate aqueous solution in oil can be added to CaCl2 solution, and thereby leads to bead formation. However, particle size cannot be easily controlled and the beads tend to coagulate into large masses before hardening properly. In the present study, the gelation of alginate-Chitosan (CH) and alginate-Gantrez® solution is achieved through the emulsification of this solution with the lipophilic phase. In a first stage, a morphological study by SEM has been realized, in order to determine the presence or absence of bead aggregates, and their shape parameters.
2006
5th World Meeting on Pharmaceutics, Biopharmaceutics and Pharmaceutical Technology
28
28
Salas S.; González-Rodríguez M.L.; Rabasco A.M. ; Fini A.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/23320
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