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| Author(s): |
Camila Fracalossi Rediguieri
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2008-04-25 |
| Examining board members: |
Osvaldo de Freitas;
Marcela Maria Baracat;
Maria Vitoria Lopes Badra Bentley;
Raul César Evangelista;
Fernando Luis Barroso da Silva
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| Advisor: | Osvaldo de Freitas |
| Abstract | |
Aqueous mixtures of polysaccharides and proteins are usually unstable and phase-separate either because of repulsive or attractive interactions. The effect of temperature, pH, and biopolymer concentration on the phase behavior of pectin/casein mixtures was investigated. A phase diagram built at pH 7 revealed that the mixture is stable at low polymer concentrations. Higher concentrations lead to thermodynamic incompatibility, driven purely by entropic forces, and to the appearance of two phases: one enriched with casein (lower) and the other, with pectin (upper). Spinodal decomposition was visualized in the early stages of phase separation. In the intermediate stages, water-in-water emulsions were observed. When the pH of these emulsions was lowered below 6, pectin was attracted by casein-rich phase, resulting in the formation of particles (diameter ~ 4 m) of pectin/casein complex, which do not coalesce and are insensitive to salt addition (100 mM NaCl). Pectin/casein microparticles obtained by this method were able to encapsulate with high efficiency either hydrophobic or hydrophilic substances and, due to that, could be applied in the encapsulation of a great variety of compounds for different purposes. In this work, the pectin/casein microparticles were used to encapsulate metronidazole crystals and the preparation of intra-periodontal pocket films with them was evaluated. Therefore, dispersions of loaded pectin/casein microparticles were dried in an oven. Films cross-linked or not with calcium sustained the in vitro drug release at least for 7 days. The cross-linking with calcium was important to reduce film disintegration, accounting for its permanence in the applied region, and to improve the mechanical properties, which facilitates manipulation and insertion into the periodontal pocket. With these results we conclude that the films formed by microparticles of pectin/casein complex loaded with metronidazole are excellent candidates for local drug delivery systems for the treatment of periodontal disease. (AU) | |