NONMEM Users Network Archive

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Re: [NMusers] Using evid 0 before dosing

From: Dennis Fisher <fisher_at_plessthan.com>
Date: Wed, 6 Nov 2019 07:23:08 -0800

Bill

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

Assuming that the drug is not an endogenous substance, the pre-dose =
concentration 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 prediction 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> =
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 in
> 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 <owner-nmusers_at_globomaxnm.com> On =
Behalf
> Of Carlos ST
> Sent: Wednesday, November 6, 2019 10:03 AM
> To: 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 - 10:23:08 EST

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