RE: [NMusers] duplicate records

From: Paul Hutson <prhutson_at_pharmacy.wisc.edu>
Date: Wed, 03 Jan 2007 11:09:12 -0600
Message Dear Pavel:
This question was also raised and discussed earlier.  Search for thread 99nov162005.html in the Users Archive.
Good luck and Happy New Year
Paul

-------- Original Message --------
Subject: RE: [NMusers] duplicate records
Date: Wed, 03 Jan 2007 09:38:19 +0100
From: Stockis Armel <Armel.Stockis@UCB-Group.com>
To: nonmem@optonline.net, nmusers@globomaxnm.com


Message
Dear Pavel
 
Personally I would tend to keep analytical issues separate from the modeling, unless you want to incorporate laboratory imprecision and/or inaccuracy in your pop-pk model.
There should be pre-established rules for defining how replicate assays are handled in order to generate final analytical results: this, as well as a robust definition of outliers (viz, when do you allow yourself to reanalyze samples ?), are fundamental GLP requirements.
For example, assuming that a sample result meets the outlier criteria, keep the first of two determinations if the reassay differs by less that 15% (or 20% for that matter), or reject the data entirely if the two results differ by more than the threshold or run a third replicate.
It is generally more convenient to perform the reassay in duplicate so that you have 3 values to chose from in your decision tree. (ie, often two values closely match and one does not).
Another set of issues would be a lack of robustness of the analytical method or unstability of the analyte in the biological matrix on repeated thawing and freezing.
 
kind regards
Armel
 
 
-----Original Message-----
From: owner-nmusers@globomaxnm.com [mailto:owner-nmusers@globomaxnm.com] On Behalf Of nonmem@optonline.net
Sent: Tuesday, January 02, 2007 14:55
To: nmusers@globomaxnm.com
Subject: [NMusers] duplicate records

Hello PK/PD Team,

We rerun assays and have duplicate PK observations per one blood sample.  It is clear that outliers should be excluded.  What do you do when both measures are similar?  Is it OK to keep and analyze both?

Kind regards,

Pavel



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--
Paul R

Paul R. Hutson, Pharm.D.

Associate Professor

UW School of Pharmacy

777 Highland Avenue

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Received on Wed Jan 03 2007 - 12:09:12 EST

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