Affiliations: Clínica Universitária de Dermatologia, Hospital de Santa Maria, Lisbon, Portugal | INSERM ERI 12, Laboratoire de Biochimie, CHU Amiens, Amiens, France | INSERM U 697, Institut de Recherche sur la Peau, Hôpital Saint Louis et Muséum National d'Histoire Naturelle, Paris, France
Note: [] Address for correspondence: João N. Silva, Clínica Universitária de Dermatologia, Hospital de Santa Maria, 1600 Lisbon, Portugal. E-mail: maiasilva@fm.ul.pt.
Abstract: Photodynamic therapy (PDT) of skin tumors or pre-cancerous lesions and of age-related macular degeneration combines the administration of porphyrins or porphyrin precursors and illumination with red light at the diseased sites. Photosensitizers absorbing light beyond 630 nm where tissues have the highest transmittance produce singlet oxygen, a highly reactive activated oxygen species and a major cytotoxin. The PDT of age-related macular degeneration is performed with red laser light after i.v. injection of verteporfin (Visudyne®) a hydrophobic porphyrin carried by serum lipoproteins whose endocytosis leads to accumulation of the porphyrin in endothelial cells of choroidal neo-vessels. In the PDT of skin cancers, local synthesis of the photosensitizer occurs after topical application of the natural protoporphyrin IX precursor δ-aminolevulinic acid (or its ester forms) on the lesions. In all the cases, the photosensitizers should be rapidly excreted to avoid a long lasting skin photosensitivity.
