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RE: Coding a triple absorption model

From: Mark Sale - Next Level Solutions <mark>
Date: Thu, 04 Jun 2009 14:28:57 -0700
Mahesh,
  Consider modeling F2 as a fraction of the = part of bioavailablilty left over after F1:
 
 LF1 = THET= A(1)*EXP(ETA(1))
 F1= LF1/(1+LF1)     &n= bsp;            = ;    
 LF2 = THETA(2)*EXP(ETA(2)) 
=  F2 = (1-F1)*(LF2/(1+LF2))     ;LF2 DESCRIBES FR= ACTION OF THE STILL AVAILABLE DOSE (1-F1)
 F3 = 1-F1-F2

&n= bsp;

Mark Sale MD
Next Level Solutions, LLC
www.NextLevelSolns.com
919-846-9185

-------- Original Message --------
Subject: [NMusers] Coding a triple absorption model
From: Samtani, Mahesh [PRDUS] <MSamtani Date: Thu, June 04, 2009 4:34 pm
To: <nmusers
Coding a triple absorption model
Dear NMusers,
I am using a dual absorption model as follows (The dose is split into 2 fr= actions and the splitting fraction, THETA(.), is an estimated parameter in = the model):
TPH == LOG(THETA(.)/(1-THETA(.)))
TH  = EXP(TPH+ETA(.))/(1+EXP(TPH+ETA(.)))
F2  = TH
F1  = 1-TH
However, upon prolonged sampling we can observe a 3rd shallow ph= ase. I would like to use a 3-depot absorption process with F1, F2 and F3== 1-F1-F2. Both F1 and F2 need etas using some type of transformation such th= at neither one of them exceed 1 nor does their sum exceed 1. Can some one k= indly provide the NONMEM code.
Thanking you in advance,
M= ahesh

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Received on Thu Jun 04 2009 - 17:28:57 EDT

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