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Re: Coding a triple absorption model

From: Leonid Gibiansky <LGibiansky>
Date: Thu, 04 Jun 2009 17:35:39 -0400


SUM=1+ EXP(THETA(1)+ETA(1)) + EXP(THETA(2)+ETA(2))
F1=EXP(THETA(1)+ETA(1))/SUM
F2=EXP(THETA(2)+ETA(2))/SUM
F3=1/SUM


--------------------------------------
Leonid Gibiansky, Ph.D.
President, QuantPharm LLC
web: www.quantpharm.com
e-mail: LGibiansky at quantpharm.com
tel: (301) 767 5566




Samtani, Mahesh [PRDUS] wrote:
> 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
>
Received on Thu Jun 04 2009 - 17:35:39 EDT

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