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Proceedings Paper

Determination of threshold dose with delta-aminolevulinic acid-induced porphyrins for effective photodynamic therapy
Author(s): Clemens Fritsch; Christoph Abels; Klaus Bolsen; Thomas Ruzicka; Alwin E. Goetz; Guenter Goerz
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Paper Abstract

In this study the metabolism in tumors and various tissues of intravenously administered (delta) -aminolevulinic acid was investigated. Amelanotic melanoma (A-Mel-3) were implanted in the dorsal skin of Syrian golden hamsters. Distribution and metabolism of i.v. injected (delta) -aminolevulinic acid in blood was studied by determination of (delta) - aminolevulinic acid and protoporphyrin concentration in red blood cells. In addition extraction of various tissues, e.g. tumor, liver, kidney, and normal skin was performed, to verify fluorescence kinetic studies by determination of total porphyrin concentration by photometry and of distribution of the porphyrin metabolites by HPLC. In untreated animals the total porphyrin concentration in all tissues examined were comparably low. In red blood cells the maximal concentration of (delta) -aminolevulinic acid as well as protoporphyrin was detected 45 min after i.v. injection of (delta) -aminolevulinic acid. Porphyrins accumulated in melanoma reaching a maximum tumor:skin tissue ratio of 6.9:1 at 45 min after i.v. injection of (delta) -aminolevulinic acid. A second high tumor:skin tissue ratio of 5.7:1 could be measured at 24 h after injection, but at this point in time the protoporphyrin content in normal skin was higher than 45 min after injection. The kidney may not be strongly affected by i.v. administration of (delta) -aminolevulinic acid, whereas the liver reveals an accumulation of porphyrins, e.g. protoporphyrin. Concluding from these results in this experimental tumor model, i.v. administration of (delta) -aminolevulinic acid seems to be a promising modality to perform photodynamic therapy more effectively and more selectively by irradiation 45 - 180 min after injection of (delta) -aminolevulinic acid.

Paper Details

Date Published: 1 March 1995
PDF: 7 pages
Proc. SPIE 2371, 5th International Photodynamic Association Biennial Meeting, (1 March 1995); doi: 10.1117/12.203385
Show Author Affiliations
Clemens Fritsch, Heinrich-Heine-Univ. (Germany)
Christoph Abels, Ludwig-Maximilians-Univ. Muenchen (Germany)
Klaus Bolsen, Heinrich-Heine-Univ. (Germany)
Thomas Ruzicka, Heinrich-Heine-Univ. (Germany)
Alwin E. Goetz, Ludwig-Maximilians-Univ. Muenchen (Germany)
Guenter Goerz, Heinrich-Heine-Univ. (Germany)

Published in SPIE Proceedings Vol. 2371:
5th International Photodynamic Association Biennial Meeting
Denis A. Cortese, Editor(s)

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