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Dear all
Anyone having the ideas about how many QCS need to keep for
regulatory toxicity studies. Because the tox samples need to be
diluted. so Diluted QCs is necessary. apart from normal QCs how many
diluted QCs need to be processed is there any guidelines . kindly
tell me.
Thanks
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I am assuming you are asking about plasma or serum samples collected
during toxicity studies. The FDA guidance is provided here:
http://www.fda.gov/cder/guidance/4252fnl.htm
The discussion of QCs says:
Once the analytical method has been validated for routine use, its
accuracy and precision should be monitored regularly to ensure that
the method continues to perform satisfactorily. To achieve this
objective, a number of QC samples prepared separately should be
analyzed with processed test samples at intervals based on the total
number of samples. The QC samples in duplicate at three
concentrations (one near the LLOQ (i.e., _3 x LLOQ), one in midrange,
and one close to the high end of the range) should be incorporated in
each assay run. The number of QC samples (in multiples of three) will
depend on the total number of samples in the run. The results of the
QC samples provide the basis of accepting or rejecting the run. At
least four of every six QC samples should be within _15% of their
respective nominal value. Two of the six QC samples may be outside
the _15% of their respective nominal value, but not both at the same
concentration.
If samples are diluted on collection and stored as diluted samples,
then I would expect QCs to be prepared in the same way. If samples
are diluted during processing, then two possible approaches are
either (1) show during validation of the method that dilution of
samples gives accurate results, or (2) process duplicate QCs at least
one concentration in any run in which sample dilution is done.
Sometimes these two approaches are combined by diluting at least the
high QC as part of the method, so it is diluted and then analyzed
both during the validation and during routine sample analysis.
This was in response to the question, "Anyone having the ideas about
how many QCS need to keep for regulatory toxicity studies. Because
the tox samples need to be
diluted. so Diluted QCs is necessary. apart from normal QCs how many
diluted QCs need to be processed is there any guidelines . kindly
tell me."
Thomas L. Tarnowski, Ph.D.
650 692-9296
ttarnowski1.-at-.aol.com
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Copyright 1995-2010 David W. A. Bourne (david@boomer.org)