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| Author(s): |
Fábia Cristina Rossetti
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: | 2010-02-25 |
| Examining board members: |
Maria Vitoria Lopes Badra Bentley;
Iouri Borissevitch;
Armando da Silva Cunha Junior;
Nereide Stela Santos Magalhães;
Antonio Claudio Tedesco
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| Advisor: | Maria Vitoria Lopes Badra Bentley |
| Abstract | |
Photodynamic therapy (PDT) is a relatively new and promising cancer treatment modality that involves the administration of a photosensitizing drug and its subsequent activation by light to produce activated oxygen species that selectively destroy target cells. Recently, PDT to treat skin cancer is focused on the development of drug delivery systems and penetration enhancers that aim to optimize the topical release of photosensitizers. Drug delivery systems based on monoolein, a biocompatible polar lipid, and water are able to enhance the cutaneous penetration of drugs and control their release. Liquid crystal nanodispersions were developed and characterized in this project as delivery systems for the photosensitizers Protoporphyrin IX (PpIX) and Zinc and Chloroaluminum phthalocyanines (ZnPc and ClAlPc), aiming to increase their topical penetration in the epidermis. The physical stability of the nanodispersions, their encapsulation efficiency and the chemical stability of the photosensitizers incorporated were tested. In vitro and in vivo skin penetration tests were performed to verify the efficacy of the nanodispersions in enhancing the topical delivery of the photosensitizers. In vitro pre-treatment tests were conducted to determine if the nanodispersions are able to increase the skin penetration of the photosensitizers by a penetration enhancing effect. Stability and encapsulation efficiency tests showed that nanodispersions are an adequate topical delivery system for photosensitizers. In vitro experiments showed increased PpIX and ClAlPc penetration in the stratum corneum, respectively, of 6.5- and 9.7-fold for the nanodispersions compared to the control. In the epidermis with dermis, without stratum corneum, the increase promoted by the nanodispersions for PpIX and ClAlPc were, respectively, of 6.5- and 9.7-fold. Experimental retention in vivo confirmed that when the nanodispersions were used as carrier, PpIX and ClAlPc concentrations in the stratum corneum were about 13.7- and 7.0-fold higher, respectively, than control. In the epidermis with dermis, without stratum corneum, only the nanodispersions were able to promote the skin penetration of these photosensitizers. Visualization of PpIX and ClAlPc skin penetration by fluorescence microscopy confirmed that the nanodispersions increased the skin penetration of these photosensitizers in deeper skin layers. The results showed that the nanodispersions are promising topical delivery systems in the PDT of skin cancer once they increased in vitro and in vivo the topical penetration of PpIX and ClAlPc in the epidermis. (AU) | |
| FAPESP's process: | 06/03929-7 - Liquid crystal nanodispersions as delivery systems for photosensitizers in the photodynamic therapy of skin cancer: in vitro and in vivo cutaneous permeation and retention tests |
| Grantee: | Fábia Cristina Rossetti |
| Support Opportunities: | Scholarships in Brazil - Doctorate |