Need assistance with a 3 compartment model

Phoenix Certara Forums Modelling and Simulation
1

Hi,

Can someone assist me in fitting the following extended release plasma conc time data? Literature suggested that the IR profiles (and IV) follows a 3 compartment model. I tried to fit it but I was not successful. :angry:

Thank you v much.

John

John-3cpt.phxproj (40 KB)

2

John,

why do you want to fit a 3-compartment model?

Please find a project file attached where I tried 1-, 2- and 3-compartments on your data. As you can see from the Theta tables the data only justifies one compartment, with tlag parameter.

Bernd

John.phxproj (939 KB)

3

Is this simulated data? Or, can you give the reference?

Bernd

4

Absorption is not 1st order - could be flip-flop kinetics?

5

Thank you Bernd. It’s real data from an extended release drug delivery system. The reason I attempted 3 compartment because published IV data suggested 3 compartment model.

6

Osmotic pump delivery ER system. 0 order release kinetics (I hate it… I recall a paper which discussed the model for a osmotic pump delivery , something like a infusion derived model.)

thanks

John

7

John,

thanks, this is valuable information. Please find attached an updated project file with:

  1. graphical model - here I tried to rebuild the osmotic pump delivery. Fit did not improve and precision of parameter estimates cannot be estimated.

  2. textual model with new distributed delay function - this new function is perfectly suited for this type of problem where you model absorption delays.

Hope, this is helpful.

Bernd

John.phxproj (1.58 MB)