Abstract
This study aimed to investigate the pharmacokinetics of a hematoporphyrin derivative in colonic tumors induced by dimethylhydrazine and adjacent normal colon in Wistar rats using anin vivofluorescence spectroscopy technique. In conventional clinical application of photodynamic therapy, the interval between photosensitizer (PS) administration and lesion illumination is often standardized without taking into account variations due to the type or localization of the tumor and intrinsic differences in the microcirculation and vascular permeability of each target organ. The analysis of the fluorescence spectra was based on the intensity of porphyrin emission band centered at around 620 nm in normal colon and colon tumors. The photosensitizer fluorescence intensity rapidly grew for carcinoma and normal colon, reaching the maximum values 1 and 3 hours after PS injection, respectively. Data presented here allow us to verify that the best compromise between selectivity and drug concentration for colon carcinoma in rats took place in the interval between 1 to 4 h after PS injection.
Highlights
Photodynamic therapy (PDT) is an established modality for the treatment against some types of cancers and other nononcologic diseases
Oxidative damage is one important component contributing to tumor therapy outcome with PDT, the effects on tumor vasculature interlinked with elicited host response play a critical role
In this study PS uptake measurements were carried out to evaluate the maximal tissue accumulation of the PS (Photogem) in dimethylhydrazine- (DMH-) induced colonic tumors and adjacent normal colon in Wistar rats using an in vivo fluorescence spectroscopy technique
Summary
Photodynamic therapy (PDT) is an established modality for the treatment against some types of cancers and other nononcologic diseases. PDT involves the interaction of the photosensitizer with a visible light of a specific wavelength and oxygen. The effects of PDT depend on the simultaneous presence of the PS, excitation light and oxygen [1, 2]. Oxidative damage is one important component contributing to tumor therapy outcome with PDT, the effects on tumor vasculature interlinked with elicited host response play a critical role [3]. The efficiency of PDT is directly related to several factors inherent to the target tissue (cellular and vascular structure of the tumor), photosensitizer (selectivity, solubility in lipid, and cellular placement), and parameters of irradiation, such as wavelength (nm), energy doses (J/cm2 ), and intensity (W/cm2 ) [4]
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