PharmPK Discussion - Convolution and Deconvolution techniques to assess Bioavailability.

• On 20 Dec 1995 at 13:52:51, "Nishit Modi" (modi.-a-.gene.com) sent the message
  

  
  David,
  
  Wagner-Nelson is considered a specialized (read limited ?) form of
  deconvolution. Limited to a single compartment analysis with first order
  absorption.  Application of convolution of deconvolution does not require
  a compartmental assumption.  Other assumptions do apply.
  
  Deconvolution can be used to characterize the absorption profile (and
  hence assess bioavailability) among other things.  And deconvolution
  does not require that an intravenous administration to be applied.  It
  depends on the question!
  
  Nishit Modi.
  
  

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• On 10 Jan 1996 at 13:09:08, "Steven L. Shafer" (Steven.Shafer.aaa.Forsythe.Stanford.Edu) sent the message
  

  
  Dear David:
  
  I consider LR and WN as parametric forms of deconvolution. However,
  I also consider conventional nonlinear regression to be a method of
  parametric deconvolution when it is used to identify a disposition
  function.
  
  Best regards,
  
  Steve Shafer
  
  

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• On 19 Jan 1996 at 11:14:32, Maria Durisova (exfamadu.at.savba.savba.sk) sent the message
  

  
  For  the  linear  dynamic  system  defined  by the weighting
  function  WF(t),  input  function  I(t)  and output function
  O(t), the system output can be expressed by Eq.1
  
  O(t)=f1(I(t), WF(t)),                              (1)
  
  where t represents time.
  The  function f1  is  the convolutory  integral.
  The system  weighting function and  the system input  can be
  expressed in the form of Eq.2  and Eq.3, respectively
  
  WF(t)=f2(I(t), O(t))                               (2)
  
  I(t)=f3(WF(t), O(t)).                              (3)
  
  The  methods  for  determination  of  the  system  weighting
  function  and the  system input   on the  basis of  Eq.2 and
  Eq.3, respectively, are called  deconvolution methods.
  
  The  Wagner-Nelson method  enables to  determine the  system
  input I(t) if the mathematical  model of drug elimination is
  known and  if the system  output O(t) can  be measured after
  extravascular administration.  This method enables  to reach
  the  same result  as does  Eq.3 but  it does  not employ the
  properties  of  the  convolutory  integral.  It follows then
  that,  in   principle,  the  Wagner-Nelson   method  is  not
  a deconvolution method.  However, it is obvious  that if the
  known  mathematical model  of the  drug elimination  has the
  weighting function  WF(t), then the same  result is obtained
  whether  the  deconvolution  method  based  on  Eq.3  or the
  Wagner-Nelson method is used.
  
  Dedik Ladislav                DEDIK.-a-.KAM1.VM.STUBA.SK
  Durisova Maria                exfamadu.aaa.savba.sk
  
  

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