Phthalocyanine: a new photosensitizer in photodynamic therapy

Photodynamic therapy (PDT) with hematoporphyrin derivative (HpD) combined with laser irradiation has been introduced as a new promising clinical method for the treatment of various malignancies. Recently, sulphonated aluminum chloro phthalocyanine (A1PC) has attracted a great deal of attention as a new photosensitizer. Tissue concentrations and photodynamic effects of A1PC and HpD, that has been using clinically in PDT, were determined in nude mice transplanted bladder tumors. According to the tissue distribution of A1PC and HpD at various times after administration, the ratios of tumoral concentration to muscular concentration of A1PC were higher than those of HpD, and skin concentration of A1PC at 24 to 168 hrs. after administration was lower than that of HpD. These results suggest that more A1PC localizes in malignant tumor than HpD, and there is a possibility of reducing skin photosensitivity with A1PC as compared with HpD. The regression of tumor volume after PDT was higher with A1PC and laser light at 670 nm than with HpD and laser light at 630 nm.