NONMEM Users Network Archive

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RE: two compartment with nonlinear elimination

From: Ken Luu <KLuu>
Date: Tue, 8 Sep 2015 15:34:41 +0000


Your concentration-time profiles seem to suggest that there’s an absorption phase which was not accounted for in your model/control stream. What was the route of administration?


From: owner-nmusers [mailto:owner-nmusers
Sent: Tuesday, September 08, 2015 7:57 AM
To: nmusers
Subject: [NMusers] two compartment with nonlinear elimination

Dear NMusers,
I'm a NM beginner modeling for a monoclonal antibody. Below is 12 subjects's individual predicted plot , it seems that nonlinear elimination (Michaelis-Menten) model can fit the data well. However, when running the control stream (two compartment models with linear and non-linear elimination), the resulting Q THETA SE% and OMEGA SE% are quite large even thought successful minimization.From the Correlation Matrix , I find that THETA (1) (VMAX) and THETA(2) (KM)are highly correlated (9.67E-01). Another problem is the .fit file can't be produced.

I have tried various error models and initial estimations, however, none had better improvement and often got error message (error 134 or parameter estimate is near its boundary). Does re-parameterization helpful ? or need to change to other models?

Any suggestions for solving the problems are highly appreciated.

(control stream will be send in another e-mail)
Received on Tue Sep 08 2015 - 11:34:41 EDT

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