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Re: [NMusers] Using evid 0 before dosing

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

Dennis,
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=
ation.
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
msale_at_nuventra.com<msale_at_kinetigen.com>


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________________________________
From: owner-nmusers_at_globomaxnm.com <owner-nmusers_at_globomaxnm.com> on behalf=
 of Dennis Fisher <fisher_at_plessthan.com>
Sent: Wednesday, November 6, 2019 7:23 AM
To: nmusers_at_globomaxnm.com <nmusers_at_globomaxnm.com>; Bill Denney <wdenney_at_h=
umanpredictions.com>
Cc: Carlos ST <carlos.serra91_at_gmail.com>; Steven Shafer <steven.shafer_at_stan=
ford.edu>
Subject: Re: [NMusers] Using evid 0 before dosing


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he message.

Bill

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

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




On Nov 6, 2019, at 7:12 AM, Bill Denney <wdenney_at_humanpredictions.com<mailt=
o:wdenney_at_humanpredictions.com>> wrote:

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=
n
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=
=0
before the first dose.

Thanks,

Bill

-----Original Message-----
From: owner-nmusers_at_globomaxnm.com<mailto:owner-nmusers_at_globomaxnm.com> <ow=
ner-nmusers_at_globomaxnm.com<mailto:owner-nmusers_at_globomaxnm.com>> On Behalf
Of Carlos ST
Sent: Wednesday, November 6, 2019 10:03 AM
To: nmusers_at_globomaxnm.com<mailto:nmusers_at_globomaxnm.com>
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,

Carlos,




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

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