LIPOSOME-MEDIATED DELIVERY OF PHOTOSENSITIZERS - LOCALIZATION OF ZINC(II)-PHTHALOCYANINE WITHIN IMPLANTED TUMORS AFTER INTRAVENOUS ADMINISTRATION

CGP55847, liposomal zinc(II)-phthalocyanine (Zn-Pc), was administered by the intravenous route to Swiss mice bearing intramuscularly implant ed Ehrlich carcinomas or to C57/BL6 mice bearing subcutaneously implan ted B16 melanomas. Tumors were removed 3 h or 24 h after dosing and th e intratumoral distribution determined by fluorescence microscopy. Loc alization of the photosensitizer occurred more rapidly in the Ehrlich carcinoma than in the B16 melanoma; this difference in photosensitizer uptake may be related to a higher degree of vascularization of the ca rcinoma. The photosensitizer was found in association with blood vesse ls at 3 h but not 24 h after dosing and appeared to have a greater aff inity for areas of tissue necrosis within the tumor compared to viable tumor tissue. Little or no Zn-Pc was detected in the muscle tissue in vaded by the Ehrlich carcinoma and was associated with membranes and t he cytosol, but not the nucleus, of cells in both tumors.