PharmPK Discussion - IVIVC Wagner Nelson Table

• On 28 Aug 2013 at 21:13:29, Chandramouli Radhakrishnan sent the message
  

  
  Hi,
  
  I am using phoenix IVIVC toolkit to establish correlation for a bioequivalence & bioavailability study.
  
  I am getting this error can some one help me how to fix this.
  
  *** ERROR: AUCINF is non-positive or undefined.  Cannot produce Wagner-Nelson/Loo-Riegelman table.
  
  This is my first time I am using this software.
  
  --
  Kind Regards
  Chandramouli Radhakrishnan
  
  

  Back to the Top

• On 29 Aug 2013 at 09:08:28, Simon Davis sent the message
  

  
  Dear Dr Radhakrishnan,
  
    the message suggest that there is a problem with your extrapolation to AUCinf.
  
    I would suggest you either send your project file to Support, or post it to the forum;
  www.pharsight.com/extranet so we can see the data that may be causing this issue.
  
     Best regards,
                           Simon.
  
  Simon.Davis.-at-.certara.com
  Senior Scientific Consultant
  Pharsight- A Certara&tm; Company
  
  

  Back to the Top

• On 29 Aug 2013 at 09:17:20, Justin Lutz sent the message
  

  
  Chandramouli-
  
  My best guess is that this error is due to a poorly defined terminal elimination rate constant (k).
  Phoenix can easily calculate AUC(0-last) via the trapezoidal method, but in order to calculate
  AUC(0-inf), the "unsampled" AUC (from T(last) to infinity) needs to be extrapolated via C(last)/k.
  If k is low or sampling was not performed long enough to confidently define k, than AUC(0-inf) can't
  be calculated and hence, the Wagner-Nelson/Loo-Riegelman deconvolution can't be performed. Hope it
  helps!
  -Justin
  
  [I agree that there could be issues with the estimation of lamba-z (slowest rate constant, aka k or
  kel ;-). I've seen analyses that seem to automatically use the last three points as if they are
  special. Often near the LOQ. Plot the data on semi-log paper and look at the points. The program may
  be estimating the terminal slope as increasing instead of decreasing. You may have an option to
  specify how the terminal slope is calculated. With Boomer I allow the analyst to specify which
  points to use or use the calculated data for the slope. Not as automatic but I think it can give
  better results when you have limited data for the terminal slope - db].
  
  

  Back to the Top

Copyright 1995-2014 David W. A. Bourne (david@boomer.org)