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Hello,
Does anybody has experienced a bioanalytical study with PK data obtained
with an internal calibration for some subjects (with IS) and with
external
calibration (without taking into account the IS) for the other
subjects. We
had a problem with the IS in several runs and unfortunately the study
samples cannot be reanalyzed again (just re-injected).
Thank you for your feeling
Henri
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Dear Henri
This would be theoretically simple but tedious practcally.
I believe you have complete validation data on IS method.
Develop complete validation data using external std method.
Analyse spiked sample from same source using both methods. (I hope your
previous method is not giving any problems with spiked samples).
Alternatively or In additiion, if you have prepared QC standards
prviously for entire study, you can analyse them by new method and
apply same rules of 15% and 20% for the combined data from two methods.
if possible repeat one or two volunters from previous lot and analyse
by both methods. comare means and CVs. Well you require IEC and other
regulatory and GCP clearances, before you can do it.
This is practically very difficult situation. May be you should seek
help in solving problems in analytical methods rather than do all this.
Allthe best
Dr.Prashant
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Copyright 1995-2010 David W. A. Bourne (david@boomer.org)