Background: Skin photosensitivity is a major side effect of photodynamic therapy (PDT). It is induced by the photosensitizer remaining in the skin. It is usually rapidly metabolized by the liver, but the pharmacokinetic profile varies widely among individuals. This makes it difficult to predict the incidence of skin photosensitivity. Therefore, we conducted a prospective study to investigate whether the NPe6 fluorescence intensity in skin after NPe6-PDT could be measured safely in human patients using a fluorescence sensing system for judging the risk of skin photosensitivity.
Methods: The NPe6 fluorescence measurements using a constructed fluorescence sensing system at the inside of the arm were acquired prior to and 5 and 10 minutes after NPe6 administration as well as at the time of PDT (4-5 hours after administration), at discharge (2 or 3 days after PDT), and at 1 or 2 weeks after PDT. Participants were interviewed as to whether they had any complications at 2 weeks after PDT.
Results: Nine male patients and one female patient entered this study. All of the measurements of NPe6 fluorescence in the skin could be obtained without any complications. The spectral peak was detected at the time of discharge (2-3 days after administration) in most cases and it decreased at 1 or 2 weeks after PDT.
Conclusions: The fluorescence of NPe6 in the skin could be detected feasibly using the fluorescence sensing system in human patients. Measuring fluorescence intensity in the skin might be useful to predict the incidence of skin photosensitivity after PDT.
We studied a 3-compartment dynamic model of talaporfin sodium pharmacokinetics in silico. Drug distribution might
change after intravenous injection from plasma to interstitial space and then into myocardial cells. We have developed a
new cardiac ablation using photosensitization reaction with laser irradiation shortly after talaporfin sodium injection. We
think that the major cell-killing factor in our cardiac ablation would be an oxidation by singlet oxygen produced in the
interstitial space in myocardium with laser irradiation shortly after the photosensitizer administration. So that the
talaporfin sodium concentration change in time in the interstitial space should be investigated. We constructed the
pharmacokinetics dynamic model composed by 3-compartments, that is, plasma, interstitial space, and cell. We
measured talaporfin sodium fluorescence time change in human skin by our developed fluorescence measurement system
in vivo. Using the measured concentration data in plasma and skin in human, we verified the calculation accuracy of our
in silico model. We compared the simulated transition tendency of talaporfin sodium concentration from interstitial space
to cells in our in silico model with the reported uptake tendency using cultured myocardial cell. We identified the
transition coefficients between plasma, interstitial space, and cell compartment, and metabolization coefficient from
plasma by the fitting with measured data.
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