A fractionated illumination scheme in which a cumulative fluence of 100 J cm−2 is delivered in two equal light fractions separated by a dark interval of 2 h has been shown to considerably increase the efficacy of 5-aminolevulinic acid (ALA)–photodynamic therapy (PDT). The efficacy of such a scheme is further increased if the fluence of the first light fraction is reduced to 5 J cm−2. We have investigated the relationship between the PDT response and the kinetics of protoporphyrin IX (PpIX) fluorescence in the SKH1 HR hairless mouse for first fraction fluences below 5 J cm−2 delivered 4 h after the application of ALA and 10 J cm−2 delivered 2 h after the application of ALA. Illumination is performed using 514 nm at a fluence rate of 50 mW cm−2. Reducing the fluence of the first fraction to 2.5 J cm−2 does not result in significantly different visual skin damage. The PDT response, however, is significantly reduced if the fluence is lowered to 1 J cm−2, but this illumination scheme (1 99 J cm−2) remains significantly more effective than a single illumination of 100 J cm−2. A first light fraction of 10 J cm−2 can be delivered 2 h earlier, 2 h after the application of ALA, without significant reduction in the PDT response compared with 5 95 J cm−2 delivered 4 and 6 h after the application of ALA. The kinetics of PpIX fluorescence are consistent with those reported previously by us and do not explain the significant increase in PDT response with a two-fold illumination scheme. Histological sections of the illuminated volume showed a trend toward increasing extent and depth of necrosis for the two-fold illumination scheme in which the first light fraction is 5 J cm−2, compared with a single illumination scheme.
How to translate text using browser tools
1 March 2003
Dose and Timing of the First Light Fraction in Two-fold Illumination Schemes for Topical ALA-mediated Photodynamic Therapy of Hairless Mouse Skin
Dominic J. Robinson,
Henriëtte S. de Bruijn,
Willem M. Star,
Henricus J. C M. Sterenborg
ACCESS THE FULL ARTICLE
It is not available for individual sale.
This article is only available to subscribers.
It is not available for individual sale.
It is not available for individual sale.
Photochemistry and Photobiology
Vol. 77 • No. 3
March 2003
Vol. 77 • No. 3
March 2003