Photodynamic therapy (PDT) has been applied in the treatment of a number of tumors. The principle of PDT is based on the application of photosensitizing chemicals followed by exposure of the tumor area to certain wavelength of light. However, prolonged skin phototoxicity after systemic administration has been frequently reported. For precancerous and cancerous lesions localized on the surface mucosal area, a mucoadhesive delivery system coudl be a better alternative to localize photosensitizers for photodynamic therapy. A buccal adhesive patch containing a photosensitizer progdrug, 5-aminolevulinic acid (ALA), has been developed in our laboratory and tested in DMBA-induced hamster buccal pouch carcinogenesis model for PDT. Fluorescence spectroscopic analysis of ALA-derived protoporphyrin IX (PpIX) was performed in normal and predysplasia buccal pouch of hamster.
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