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Dear all,
I would like to have your opinion regarding the PK analysis of data
in mice when plasma concentrations are positive at pre-dose (Time 0
before dosing) and in control samples. Do you perform the PK analysis
and mention that PK parameters are overestimated due to positive
plasma concentrations in pre-dose/control samples or you prefer not
to perform the PK analysis at all as the data will probably be
unreliable. Any opinion will be greatly appreciated.
Many thanks in advance,
Samia
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The following message was posted to: PharmPK
First and foremost, investigate the cause of these values being positive
for concentration (T=0 and blank samples) . Making interpretation at
this point might be futile in the absence of adequate explanation.
Jean-Pierre Moreau
Principal Scientist
Drug metabolism and PK
MDS Pharma Services
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The following message was posted to: PharmPK
Dear Samia:
There are several points to consider:
1) Is this pre-dose consistent in all control and
pre-dose samples?
2) What is your bio-analytical method based on?
LC/MS/MS? Is it to due to matrix effect (some
indigenous molecule with the same transition file)?
3) What is the purpose of the study (early
research/discovery/screening studies or more
definitive studies)?
4) How much contamination do you see? What % of the
Cmax is presented by Pre-dose? Is it possible this is
due to carry-over? Were blank samples placed after a
high QC/standard?
Rostam
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Dear Samia
If a control result is positive when it is supposed to be negative
then the results should be rejected. I think you should have a
crieria for aaccepting and rejecting control samples. same applies to
pre-dose sample.
In bioequivalence results performed in human, volunteer data should
be excluded if his pre-dose sample is greater than 5% of the Cmax
value of the respective phase according to FDA guidelines.
hope this helps
regards
Isra' Admour, M.Sc Pharm
Regualtory Affairs Director
International Pharmaceutical Research Center (IPRC)
Tel: +962-6-5627651/52/48 (ext. 213)
PO Box 963166, Amman11196, Jordan
www.iprc.com.jo
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The following message was posted to: PharmPK
Hi,
Is this a single dose study ?
Is it a dietary-dose study ?
It seems to me that you may have a fundamental problem of cross-
contamination
and a focus on the experimental method rather than analysing the data
would be
your primary aim
Good Luck
Dave Vowles
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Copyright 1995-2010 David W. A. Bourne (david@boomer.org)