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Trough concentrations and ADDL

From: Elisabet Størset <elisabet.storset>
Date: Wed, 11 Jan 2012 15:47:48 +0100

I am a new NONMEM user and have a simple question regarding the input file.

I am analyzing trough concentrations in a multiple oral dose study. 20
trough concentrations are available per patient over a period of 10-12
weeks. The dose is frequently changing due to TDM. I wonder how it is
recommended to code the dosing history in the inputfile effectively in this
situation.

I'm considering using ADDL, but am unfamiliar with it and unsure if I am
using it correctly. This is a selected part of the inputfile:
    ID DAT1=DROP TIME EVID C=DV DOSE II ADDL 1 *01.01.2008* 20 1 0 4 12=
 4 1
*03.01.2008* 8 0 6,1 0 0 0 1 *04.01.2008* 8 0 7,6 0 0 0 1 *04.01.2008* 8 1 =
0
4 0 0 1 *04.01.2008* 20 1 0 3 12 12 1 *06.01.2008* 8 0 5,4 0 0 0 1 *
08.01.2008* 8 0 5,6 0 0 0 1 *11.01.2001* 8 0 4,4 0 0 0 1 *11.01.2008* 8 1 0
3 0 0 1 *11.01.2008* 20 1 0 3,5 12 20 1 *13.01.2008* 8 0 5,0 0 0 0

Is this similar to the way other nmusers use the ADDL item?
Will NONMEM analyze the above data file with the same results, compared to
this more simple, but less effective code (only first records):

     ID DAT1=DROP TIME EVID C=DV DOSE 1 *01.01.2008* 20 1 0 4 1 *02.01.=
2008*
8 1 0 4 1 *02.01.2008* 20 1 0 4 1 *03.01.2008* 8 0 6,1 0 1 *03.01.2008* 8 1
0 4 1 *03.01.2008* 20 1 0 4 1 *04.01.2008* 8 0 7,6 0 1 *04.01.2008* 8 1 0 4
1 *04.01.2008* 20 1 0 3 1 *05.01.2008* 8 1 0 3 1 *05.01.2008* 20 1 0 3

When doing the top approach, I have to calculate the number of doses to
fill the ADDL item, which can be complicated if the time before the dose is
changed is several weeks. This could give errors. Is there a way NONMEM
could understand that "the patient will use this dose at 12 hour intervall
until a new dose record is stated"?

Thank you in advance for helping!

Kindly regards Elisabet Strset, new nonmemuser.

Received on Wed Jan 11 2012 - 09:47:48 EST

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