Zn-Phthalocyanine as a Possible Phototherapeutic Agent for Tumours
The use of phthalocyanines as photosensitizers in the photodynamic therapy (PDT) of tumours is raising the interest of several research and clinical groups because of the large potential advantages of these dyes. In particular, phthalocyanines are better tumour-photosensitizers than many porphyrins (1). We are using Zn(II)-phthalocyanine (Zn-Pc), which has a high degree of purity and can be readily incorporated into small unilamellarliposomes of dipalmitoyl-phosphatidylcholine (DPPC) (2). Preliminary PDT studies performed by injecting Balb/c mice bearing a transplanted MS-2 fibrosarcoma with 0.5 mg/kg Zn-Pc showed that an extensive necrosis of the tumour tissue can be obtained by irradiation with ca. 660 nm-light (total 2 2 light dose: 300 J/cm2; dose-rate: 270–370 mW/cm2). Therefore, it appears of interest to investigate the detailed aspects of the mechanisms by which Zn-Pc is accumulated and retained by tumours and, once photoactivated, causes the necrosis of the tumour tissue. In this paper, we report some pharmacokinetic and ultrastructural studies with Zn-Pc in vivo.
KeywordsPorphyrin Phthalocyanine DPPC Fibrosarcoma Hematoporphyrin
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