Steady state data-error

Phoenix Certara Forums Modelling and Simulation
1

Hello,

I am modeling (population) a drug which has achieved steady state. I have added an SS column to the data where in t=0 has a value of 1 and the rest is 0. The drug is taken every 24 hours. I tried to run a base model, where I selected the SS checkbox and I kept Dosepoint as Aa (the dose) and Amount as AMT and delta time as constant (24)

However I’m getting the following error-

Error: unable to achieve steady-state for Subject “2”

Wonder what the problem is?

Thank you,

Meenakshi

2

Need the project to help.

This means that the model is defined in such a way that steady state cannot be reached but to find why I need the project.

For the meantime you can try the following.

Shift all your observed data by let say at least 10 dosage intervals. If dose interval is 24, then by 240 hours.

Now from 0 to 240, no observed data but now you put ADDL=10 and II=24 (DOSAGE INTERVAL).

Now your model will run from 0 to 240 and look if you reached steady state or that steady state cannot be reached.

Then please send me the project for me to review.

If data are confidential you can send me the project with data blanks except the headers.

Then we will see what is going on.

best Regards

Serge

3

Thank you sir! I have attached the project for your reference. When I added the SS column, and checked the SS box in the input options, the model finally ran. However, if I mapped the SS column to the SteadyState the above error came again!

LogLikelihood value- the smaller value is better right? I am getting an extremely small value for 2 cmpt model but the diagnostics are way off!

Could you please tell me the ADDL column details again, I did not understand

Thank you sir,

Regards,

Meenakshi

4

Sorry, forgot to upload in last message. Attached here for your reference.

Thank you very much!

Drug.phxproj (4.57 MB)

5

Hi Meenakshi,

I am getting an extremely small value for 2 cmpt model but the diagnostics are way off!

Could you please specify what kind of diagnostics do you mean? I got the results using Model_multiplicative_2cmpt with SS mapped. Return code is 3, diagnostics is not so good, but all plots/worksheets are presented

However, if I mapped the SS column to the SteadyState the above error came again!

Which model do you mean? You have 6 on the board

Could you please tell me the ADDL column details again, I did not understand

Very nice examples about ADDL usage you can find in the user’s guide. They are really good and clear.

Mittyright