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Re: [NMusers] Easier IOV modeling

From: Jeroen Elassaiss-Schaap (PD-value B.V.) <"Jeroen>
Date: Wed, 16 Jan 2019 09:14:53 +0100

Hi Sebastien,

Interesting notion, thanks. It should be possible from NM7.3 onwards
using MOD or DECLARE as described in the sections just below the one you
referenced.

With DECLARE it could look like this:

$ABBR DECLARE INTEGER IOCC
$PK
CALLFL=-2
IF (NEWIND < 2) IOCC=0
IF (AMT > 0 .and. CMT==1) THEN
  IOCC = IOCC + 1
ENDIF
IF (IOCC>MAXOCC) IOCC = MAXOCC ; define MAXOCC in the dataset or in code
to prevent referencing more than defined in $OMEGA
...
IOVCL = ETA( 1 + IOCC*3 ) ; first dose occasion will get assigned eta(4)
as below, than 7, 10 etc...
CL    = TVCL * EXP( ETA(1) + IOVCL )


And using MOD on TIME, assuming regular nominal daily dosing, it could
look like:

$ABBR DECLARE INTEGER IOCC
$PK
IOCC  = ( TIME - MOD( TIME, 24) )/24 + 1  ; assume TIME in hours and
starting at zero
IOVCL = ETA( 3 + IOCC*3 ) ; first day will get assigned eta(4) as below,
than 7, 10 etc...
CL    = TVCL * EXP( ETA(1) + IOVCL )


And therefore I think it could be possible indeed. I however do not
think it is easier, and I see OCC coding in the dataset as more robust.
But in cases where it is not possible to modify the dataset, such an
approach might be an option. As a reclaimer: the above code snippets are
heavily leaning on the userguide examples and completely untested.
Please test before use.

Hope this helps,

Jeroen

http://pd-value.com
jeroen_at_pd-value.com
_at_PD_value
+31 6 23118438
-- More value out of your data!

On 16-01-19 04:06, Sebastien Bihorel wrote:
> Hi
>
> The Introduction to NONMEM 7.x documents include a section entitled "Easier Inter-occasion variability modeling" which describes a quicker way to code IOV.
>
> $ABBR REPLACE ETA(OCC_CL)=ETA(4,7,10)
> ;when OCC=1, eta(4) to be used: when OCC=2, eta(7) to be used, etc.
>
> ...
>
> $PK
> CL=TVCL*EXP(ETA(1)+ETA(OCC_CL))
>
> When this approach is used, OCC must be a data item defined in $INPUT.
>
> Is there a similar way to code ETAs using a dynamic variable defined in $PK?
>
> Thanks
>
> Sebastien
>
>

Received on Wed Jan 16 2019 - 03:14:53 EST

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