Re: Using evid 0 before dosing
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/
Quoted reply history
> On Nov 6, 2019, at 7:12 AM, Bill Denney <[email protected]> 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: [email protected] <[email protected]> On Behalf
> Of Carlos ST
> Sent: Wednesday, November 6, 2019 10:03 AM
> To: [email protected]
> 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,
>