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Dear all,
I would like to seek your advise with respect to the distribution of
a radiolabelled test compound (known to absorb UV light) to light
exposed tissues, skin and eyes in rodents.
How does one interpret the results of such a study with respect to
its safety implications (phototoxicity)? For example, how far into
the skin does UV light penetrate to be relevant for interaction with
the test compound? How can one assess if the extent of distribution
into such tissues should raise a safety concern or not? How do
regulatory authorities look at such issues? Direction to relevant
references (excluding the EMEA and FDA guidances...) are mostly
appreciated.
Many thanks
Gary
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Hello Gary,
Those are interesting questions..Is your test compound applied on the
skin? In my opinion the penetration of light into the skin would
depend on the type and mode of application of the test compound.
Normally, the UV light (UVC) can penetrate well into the vasculated
dermal-epidermal junction.. But if you are applying you test compound
on the skin and it is absorbing UV light, I guess it would depend on
the type of the compound--max wavelength.. There are some studies
done using EPR to study the free radical chemistry.
Damiani et al;Free Radic Res. 2006 May;40(5):485-94.
Hope this helps..Sree
Sree Kasichayanula
Biovail Contract Research
Toronto, Canada
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The following message was posted to: PharmPK
Dear Gary, have a look at the guidelines related to the cosmetics
safety,
look at the Joint research center web site for example. The basic
principle
is to study first the phototoxicity of your compound, there is a
validated
test (at the OCDE level) for that, called the 3T3 NRU test.
Christophe Chesne
Eurosafe
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