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Re: Using evid 0 before dosing

From: Mark Sale <msale>
Date: Wed, 6 Nov 2019 16:40:49 +0000

I may have to disagree, a little. There is information, a little, in a pre =
dose BQL, about assay precision. I think you might agree that is a pre dose=
 sample is NOT BQL (which happens), tells you (and NONMEM) something about =
the assay. Converse, even a BQL predose sample has a small amount of inform=
That not withstanding, we also remove and pre-dose BQLs from the data set.

Mark Sale M.D.
Senior Vice President, Pharmacometrics
Nuventra Inc.
2525 Meridian Parkway, Suite 200
Durham, NC 27713
Phone (919)-973-0383

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From: owner-nmusers
 of Dennis Fisher <fisher
Sent: Wednesday, November 6, 2019 7:23 AM
To: nmusers>
Cc: Carlos ST <carlos.serra91>
Subject: Re: [NMusers] Using evid 0 before dosing

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I think that the issue is more complicated than you acknowledge.

Assuming that the drug is not an endogenous substance, the pre-dose concent=
ration is likely to be BQL. However, there are two kinds of BQL values:
1. Samples that are truly zero because they were obtained pre-dose
2. Samples that are > 0 but < LOQ.
Yet both are reported as BQL.

From my perspective, a BQL value pre-dose provides no information to NONMEM=
. Therefore, one should apply EVID=2 to that sample. This allows a pred=
iction at that timepoint but the sample does not influence the analysis.


Dennis Fisher MD
P < (The "P Less Than" Company)
Phone / Fax: 1-866-PLessThan (1-866-753-7784)<>

On Nov 6, 2019, at 7:12 AM, Bill Denney <wdenney

Hi Carlos,

It is commonly used. For most datasets, there will be at least one
observation that occurs before dosing to estimate the baseline value, and i=
almost every scenario, the modeling dataset should mirror the real world
actions. So, there is no issue with it, and usually you will have an EVID=
before the first dose.



-----Original Message-----
From: owner-nmusers
Of Carlos ST
Sent: Wednesday, November 6, 2019 10:03 AM
To: nmusers
Subject: [NMusers] Using evid 0 before dosing

Dear NMUsers,

I would like advice in the best practice to use evid 0 before dosing, which
is to say an observation just before a dosing (*to estimate the value in
that compartment just before dosing event).

Thank you,


Received on Wed Nov 06 2019 - 11:40:49 EST

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