Fit mulple dose data using Model defined in ASCII Format

Phoenix Certara Forums Phoenix WNL basics
1

Does anyone have any suggestions on how to program a model for fitting multiple doses (infusion) defined using the ASCII Format option (WinNonlin Phoenix 6.4)

Thanks,

Barry

2

Barry, the ASCII model code is essentially obsolete, if you have to write any new model code I would highly recommend that you use the Phoenix model engine since supporting multiple dosing is implicit and no extra code needs to be written.

Also if you can’t build your model from the drop down options in the first tab you have access to both graphical and textual editor modes. (Note there are quite a few existing models already on here if you search).

Simon.

3

Hi Simon,

Thanks for getting back to me, I needed to fit a multiple-dose infusion (constant: dose, infusion rate and dosing interval) and successfully used the code below (in case someone should find it of use). The nonabsorption parameters are meant for illustrative purposes only. Unfortunately, I have found using the Phoenix model engine to fit simple nonlinear regression a bit troublesome.

Code template--------------------------------------------------------------

IF (x LE CON(4))Then

IF (((x/CON(3)) - INT(x/CON(3)) )*CON(3) LE CON(1)) THEN

dz(1)=(CON(2)/CON(1)) - (K12 + K10) * z(1) + K21 * z(2)

ELSE

dz(1)=-(K12 + K10) * z(1) + K21 * z(2)

ENDIF

ELSE

dz(1)=-(K12 + K10) * z(1) + K21 * z(2)

ENDIF

where:

CON(1) is Infusion time

CON(2) is the infused dose

CON(3) is the dosing interval

CON(4) is time of last dose + dosing interval

Basically the outer IF statement turns off the infusion past the last dose. The inner IF statement turns the infusion input on/off. The key part is the use of: Integer(Time/Dosing interval) *Dosing interval compared to (Time/Dosing interval)*Dosing interval

4

Thanks for posting the ASCII code for others however I’m still a bit puzzled about the problems you’re reporting with the Phoenix model engine; it should in most case be the more powerful tool, certainly more flexible so if you have a problem that you think does not work well I’d be interested to see it. Either as a test case or if possible to provide you and others some usage tips.

Simon