RE: Coding a triple absorption model
Title: Coding a triple absorption model
Mahesh, Consider modeling F2 as a fraction of the part of bioavailablilty left over after F1: LF1 = THETA(1)*EXP(ETA(1)) F1= LF1/(1+LF1) LF2 = THETA(2)*EXP(ETA(2)) F2 = (1-F1)*(LF2/(1+LF2)) ;LF2 DESCRIBES FRACTION OF THE STILL AVAILABLE DOSE (1-F1) F3 = 1-F1-F2 Mark Sale MD
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-------- Original Message --------
Subject: [NMusers] Coding a triple absorption model
From: "Samtani, Mahesh [PRDUS]" < [email protected] >
Date: Thu, June 04, 2009 4:34 pm
To: < [email protected] >
Dear NMusers, I am using a dual absorption model as follows (The dose is split into 2 fractions 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 phase. 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 that neither one of them exceed 1 nor does their sum exceed 1. Can some one kindly provide the NONMEM code. Thanking you in advance, Mahesh