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The following message was posted to: PharmPK
Dear All
Does any body have any expertise in using "Pharsight Wininlin"
Michalis-Menton model to analyse "protein compounds?. Do you need to
calculate the following parameters manually as it is a requirement in
the "model parameters tab" (Model 303)? I realise you require repeat
dosage regimes/ intervals and steady state plasma concentrations.
v_f
K01
vm
km
Please advise
Much appreciated
John.
Dr. J. Odontiadis
Senior Scientist (Bioanalytical)
RDDT (Build 223, L2 Rm 47)
School of Medical Sciences
RMIT University
Bundoora Campus,VIC 3083
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Dear All
Does any body have any expertise in using "Pharsight Winonlin"
Michalis-Menton model to analyse "protein compounds?. Do you need to
calculate the following parameters manually as it is a requirement in
the "model parameters tab" (Model 303)? I realise you require repeat
dosage regimes/intervals and steady state plasma concentrations.
v_f
K01
vm
km
Please advise
Much appreciated
John.
Dr. J. Odontiadis
Senior Scientist (Bioanalytical)
RDDT (Build 223, L2 Rm 47)
School of Medical Sciences
RMIT University
Bundoora Campus,VIC 3083
E: john.odontiadis.aaa.rddt.com.au
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The following message was posted to: PharmPK
Dear Dr Odontiadis,
The Michalis-Menten model (Model #303) implemented in WinNonlin will
need you to give it initial estimates of these parameters; v_f, K01,
vm & km. This is the case for any "ascii" model in WinNonlin i.e.
one where you can see the code when you apply the model since
WinNonlin's integral stripping algortithm implemented in these models.
WinNonlin will then search from these initial estimates, so they
don't need to be exact just a starting point, if you get errors one
thing to check is that you have given an appropriate search space, by
default WinNonlin's upper bounds are 10 times the initial estimates
with lower bounds set to zero.
You may also find it useful to consider one of our intermediate or
advanced modelling classes;
http://www.pharsight.com/training/training_home.php
Alternatively you could explore some of the example data and
corresponding WinNonlin models provided in the book "Pharmacokinetic
and Pharmacodynamic Data Analysis: Concepts and Applications" by
Johan Gabrielsson & Daniel Weiner. The Fourth Edition came out
earlier this year. Finally, please don't forget you can contact
support.-at-.pharsight.com [Case: 00061251].
Best regards,
Simon.
--
Simon Davis
Senior Scientific Consultant
Mobile : +44 7980 832 666
Facsimile : +1 801 991 7145
Home Office : +44 113 274 1198.
--
Forthcoming meetings
LabLogic's UGM, 6-7th June 2007, Sheffield, UK.
http://www.lablogic.com/NewsDisplay.asp?
Name=LabLogic2007LIMSandRadiochromatographyUserGroup
PAGE 2007, Kobenhavn, Denmark
16th Population Approach Group Meeting, 13-15 June, 2007
http://www.page-meeting.org/default.asp?id=31&keuze=meeting
[Also be very careful with units for vm and km. It is easy to get
confused between amount and concentration units (e.g. vm = mg/hr or
mg/ml/hr). If differential equations are involved you are probably
using amount units. While the initial estimates don't need to be
exact it is better if they are close. Simon, does WinNonlin still
transform the parameters during the fitting process? A lower limit of
zero for v_f could cause a problem - db]
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