29th Annual Meeting of the American Society of Photobiology

Downtown Marriot

Chicago, Il.

Transdermic patches for Photodynamic Therapy of superficial skin lesions.

Abstract-
In this communication we are reporting the results of an ambulatory photodynamic therapy (PDT) of skin actinic keratoses, basal and squamous cell carcinomas applying a novel approach to deliver the photosensitizer. We found that this procedure was simpler, effective and well tolerated for the patients. For this purpose we have produced a self adhesive black patch loaded with a thin layer of 5 aminolevulinic acid (ALA) powder. The patches protected from light exposure for transportation were given to patients who applied them over the lesions, previously rubbed with a Dermobase cream. After 6h the patches were removed and lesions submitted to PDT. In this study we used as irradiation source a prototype developed in this Laboratory, consisting of 100 LEDs 630 (MCD) distributed symmetrically in a bowl shaped concave surface about 10 cm in diameter. This provides 31 mW/cm² power density and 155 mW power with a brightest center area about 5cm² . This procedure was successful in all cases treated and usually one application was sufficient for remission of the lesions. In some cases with lesions presenting folds or wrinkles impairing the patch adherence, additional PDT sessions were needed. The transdermic administration of the photosensitizer described here significantly reduced the presence of the patients in the hospital and solve one of the main causes of interruption of treatment, the prolonged periods of idleness between the application of the drug and the irradiation (4 to 6h). With this method the patients and operators can regulate their working schedule and expend a minimum time in hospital wards just for irradiation.

Keywords: photodynamic therapy, transdermic system, transcutaneous patches, skin lesions