Dear Katrin,
You still could code your model in $ERROR using TIME, as your diurnal
rhythm is proportional to baseline.
If you would like to explore indirect models, you could try the harmonic
approach as described in Chakraborty et al. 1999 -
http://europepmc.org/abstract/med/10533696; the beauty is that you can
model the baseline in $PRED and use these estimates right into $DES for
your drug effect on kin.
For blood pressure rhythms you might also want to try the more flexible
model laid out by Sallstrom et al. 2005,
http://europepmc.org/abstract/med/16328099.
Hope this helps,
Jeroen
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Op 28-07-15 om 08:07 schreef Katrin Volz:
Dear Bill, dear all
Thanks so much for your answer.
More concrete I would like to model blood pressure including a
circadian rhythm. Therefore I would like to use a sine or cosine
function with ‘T’ instead of ‘Time’.
SinfS = ( 1 + Amplitude * sin ( (2*PI/Period) * (T-Phase) ) ) ; sine
or cosine function
SBP = (SBas + SinfS) * (1-EffS)
; SBP = systolic
blood pressure, SBas = Baseline systolic blood pressure, (1-EffS = effect)
I could also model this effect using a turnover model and avoid this
problem, but I would like to evaluate this kind of PD model (if there
is any meaningful way to code).
I also had the idea to code this sine function as a function of time
in a compartment and rename this compartment in $Error, but I am not
sure if there is any way to do this.
Thanks again and best regards.
Katrin
*Von:*Denney, William S. [mailto:[email protected]]
*Gesendet:* 27 July 2015 17:34
*An:* Katrin Volz <[email protected]>;
[email protected]
*Betreff:* RE: [NMusers] Time 'T' in $Error
Hi Katrin,
$ERROR is executed once per data row. The time when $ERROR is run is
the TIME value (the discrete times of the measurement). For this
specific example, you can just use TIME. You will need to code your
$DES block so that what you’re wanting to integrate as a function of
time is in a compartment amount (e.g. A(1)). With your example, it’s
hard to see how T is used in the $DES, but perhaps you could share the
real example to give a bit more concrete advice on how to integrate
the answer into your code.
Thanks,
Bill
*From:*[email protected]
<mailto:[email protected]>
[mailto:[email protected]] *On Behalf Of *Katrin Volz
*Sent:* Monday, July 27, 2015 10:46 AM
*To:* [email protected] <mailto:[email protected]>
*Subject:* [NMusers] Time 'T' in $Error
Dear NMuser,
I would like to model a PD effect using a function which includes
continuous time ‘ T ’.
The PD Effect is coded in $Error.
In general like this:
*$ERROR*
MyFunction = xxx + T
PDEffect = Basline * MyFunction
But ‘T’ cannot be used in $Error.
I tried to code the function with ‘T’ in $DES and rename it to use it
in $ERROR:
*$DES*
MyFunction = xxx + T
*$ERROR*
MyNewFunction = MyFunction
PDEffect = Baseline * MyNewFunction
but it didn’t worked (to rename was not permitted by NONMEM).
Does anyone of you has an idea how to solve this problem?
Thanks and best regards.
Katrin
Anke-Katrin Volz
PhD Student
Saarland University
Clinical Pharmacy
Campus C2 2 | Room 0.31
D- 66123 Saarbrücken
mail [email protected]
<mailto:[email protected]>
fon +49 [0]681 302 22 84
fax +49 [0]681 302 70 258
www.clinicalpharmacy.me <http://www.clinicalpharmacy.me>
