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Hello Guys!
I needed an urgent solution for my query.
I am doing biodistribution studies of Nanoparticles in a mouse model.
The drug of interest is tritiated is encapsulated within the matrix
of PLGA nanoparticle and is injected i.v in mice.
After homgensing the tissues and solubilizing it, I am performing
Liquid Scintillation Counting. The solution is clear.
The question is: How should I express the drug levels as?? I am
reporting the values as % Injected dose, in each organ. However, due
to shielding effect of polymer coupled with that of tissue, I am
unable to recover the 100% radioactivity. Can anyone here please help
me out with this?
Thankss so much!!
Regards,
Kavita
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hello
You need to report ucurie or millicurie/gram of tissue . the
concentration would be reported in radioactivity units only.
The final level should be 100% to that of all organs radioactivity.
that is called massbalence.
i hope this helps for you. thanks
A.Karthik
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The following message was posted to: PharmPK
Kavita:
The ongoing discussion on your question leads me to remind the
community that, depending on the questions that need to be answered,
biodistribution studies using the "cut-and-count" principles only
give you information at one point in time - when the animal was
euthanized or, in humans, when a biopsy sample was taken. There is no
real dynamic information in such measurements, unless you take a
large number of animals at various time points, and even then you
will only get an average that obliterates any inter-subject variability.
Noninvasive imaging must be the method of choice when you want to
generate dynamic measurements, and when you want to study the effect
of a given treatment on drug biodistribution. Such noninvasive
measurements (for which we have been using the term Pharmacokinetic
Imaging) can be performed using radiolabeling (e.g., 11C, 18F and
other radionuclides), or NMR spectroscopy (2H, 13C, 19F or other NMR
detectable nuclides). And such methods are usable in both animals and
humans.
--
Professor Walter Wolf, Ph.D. Distinguished Professor of
Pharmaceutical Sciences
Director, Pharmacokinetic Imaging Program
Department of Pharmaceutical Sciences, School of Pharmacy
Chair, Biomedical Imaging Science Initiative
University of Southern California 1985 Zonal Ave., Los Angeles, CA
90089-9121
E-Mail: wwolfw.aaa.usc.edu
Telephone: 323-442-1405
Fax: 323-442-9804
http://www.usc.edu/research/initiatives/biomedical_imaging/index.html
http://www.usc.edu/schools/pharmacy/faculty_directory/detail.php?id=59
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Dear Colleagues,
For NDA submission of a new drug candidate given via both iv
and oral routes (for the same application), what are the tissue
distribution and
mass balance data requirements? For both route of administration or
iv would be
adequate?
Rostam
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Copyright 1995-2010 David W. A. Bourne (david@boomer.org)