ABSTRACT
In photodynamic therapy (PDT) or photodynamic antimicrobial chemotherapy (PACT), which is to be used clinically, effective delivery methods of both light and photosensitizer to the site of action are necessary. Because of limited light penetration through tissue, clinical PACT would be necessarily used or applied to areas of the body where light can be delivered relatively easily, such as the skin and body cavities. Light delivery onto the skin is simple and has been frequently employed in PDT of dysplastic and neoplastic diseases. In PDT, however, the photosensitizer or its precursor is often administered orally or intravenously. Because of disordered metabolism and blood flow peculiar to dysplastic or neoplastic tissue, photosensitizing concentrations of drug molecules accumulated in the target lesions are relatively higher. Targeting the photosensitizers to wound infections in this way is not possible, and so the drug must be applied topically. Factors such as physicochemical properties of the photosensitizer dose, percentage of photosensitizer to be delivered, barrier properties of the target site, and patient acceptability all have a major impact upon the method of drug delivery.
