| 摘要 |
A system and a method using photodynamic therapy for treatment of epithelial diseases are provided, wherein the photosensitizers used have enhanced selectivity for the affected region so that the treatment has reduced or no side effects. Selectivity is achieved by avoiding systemic application of the photosensitizer and by topically applying the photosensitizers with certain carriers. Compositions of hydrophilic medical or cosmetic carriers like ointments, creams or lotions can be used. Hydrophobic photosensitizers such as bacteriopheophorbide and its derivatives are preferred because of their ability to penetrate tissue and to distribute evenly, as well as their low threshold of phototoxicity. After the phototoxic sensitizer has been administered to the afflicted tissue, the tissue is irradiated with an appropriate radiation source, such as sunlight or a radiation source emitting a defined wavelength like a diode laser. Deeper penetration of the radiation may be achieved with longer wavelengths (700-800 nm), which are in the red part of the spectrum. The photosensitizing agent can be topically applied easily and repeatedly, and thus the system is especially useful for treating diseases like psoriasis, where frequent and repeated treatments may be necessary. A method of photodynamic therapy for epithelial diseases is also provided, which comprises the steps of: (a) applying topically a therapeutically effective amount of the photosensitizer like bacteriopheophorbide or a bacteriopheophorbide derivative to an area afflicted by an epithelial disease or an infection, and (b) exposing the treated area to radiation to photoactivate the photosensitizer to produce a cytotoxic response in the afflicted area. |
