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Determination of the peak absorption wavelength and disaggregation kinetics of TOOKAD in vivo using dynamic, spatially resolved diffuse reflectance spectroscopy in a rabbit model
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Paper Abstract

TOOKAD (WST09: Steba Beheer, Netherlands) is a bacteriochlorophyll-based photosensitizer with a near-infrared absorption at approximately 760-770 nm in its photoactive monomeric form. In aqueous solution the drug aggregates into a non-photoactive form, with an absorption maximum at approximately 812-825 nm. We describe non-invasive pharmacokinetic measurements using diffuse reflectance spectra (DRS) with a surface contact probe in a rabbit model. Spectra were collected over a 120 min period encompassing infusion and clearance of TOOKAD. Factor analysis of the spectra was used to calculate the disaggregation rate to the monomeric form, vasculature clearance, and accurate in vivo spectra of each form of the drug. Immediately following infusion, the drug has a significant aggregated component. Disaggregation occurs with a rate constant, k equals 0.07 min-1. Peak monomer concentration occurs < 30 min post-infusion, then begins clearing from the skin at a rate k equals 0.004 min-1. The monomer in vivo absorption spectrum has a peak at approximately equals 765 nm, while the aggregate peak is at 830 nm.

Paper Details

Date Published: 1 May 2002
PDF: 8 pages
Proc. SPIE 4613, Optical Biopsy IV, (1 May 2002); doi: 10.1117/12.465239
Show Author Affiliations
Robert A. Weersink, Photonics Research Ontario (Canada)
Brian C. Wilson, Ontario Cancer Institute (Canada)
Michael S. Patterson, Hamilton Regional Cancer Ctr. (Canada)

Published in SPIE Proceedings Vol. 4613:
Optical Biopsy IV
Robert R. Alfano, Editor(s)

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