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Re: simluation Tmax Cmax AUC

From: Sebastien Bihorel <Sebastien.Bihorel>
Date: Thu, 22 Apr 2010 14:45:02 -0400

I am not sure how you ended up with:

Ke-2.1*Ln(Ke)=3.18

but you may want to look at the following link, which explain how the
Lambert function (not available in NONMEM as far as I know) could help
to solve for Ke:
http://www.mathhelpforum.com/math-help/pre-algebra-algebra/58685-solving-ln-x-kx.html.

The Lambert function should be available in Maltab, Mathematica, Maple,
or similar tools.

Sebastien

yhb5442387 wrote:
> Dear Sebastien:
> I have to say that my admiration to you is beyond the words,because you have directly pointed out the radical essence.Could the ke or the V/F,any one , be derived from the known Cmax,AUC,?As far as I have leaned ,the equations are as follows:
> AUC=Dose*F/Ke*V,
> Cmax=(F*Dose/V)*(exp(Ka*Tmax)-epx(Ke*Tmax)).
> After the computation and transformation ,I was obstructed in the front of the following
> : Ke-2.1*Ln(Ke)=3.18.
> something like that, well I could not remember the constant number (2.1 e.g.) clearly. I am not able to solve that equation.
> So,I decide to make some equations in the $PK,in which the CL V and Ka could all be expressed as the component of Tmax ,Cmax,and AUC at the same time.The suggestion you have made is usefull,but still a little problem :the Ke.
> Thank you for your generous help.
> 22 03:24:55,"Sebastien Bihorel" <Sebastien.Bihorel
> >
> >It looks like you are trying to derive the unknown values of KA, CL/F
> >and V/F from the known values of Tmax, Cmax and AUC (probably obtained
> >from a non compartmental analysis).
> >
> >If that is really the case, you will need to know the values of the
> >half-life of elimination or the slope of elimination Ke to solve for Ka
> >and V/F (the following solutions assume a one-compartment model with
> >linear absorption and elimination):
> >
> >CL/F = Dose/AUC
> >
> >V/F = (CL/F)/Ke
> >
> >KA = - (1/tmax)*ln[ exp(-ke*tmax) - (Cmax*V)/(F*dose) ]
> >
> >If you don't know Ke, you will have to solve for V/F and Ka numerically,
> >prior to your simulation.
> >
> >Sebastien
> >
> >yhb5442387 wrote:
> >>
> >> Dear Nmuser:
> >>
> >> I would like to do a data simulation .The distributions of the drug
> >> population pharmaockinetics were assumed to be normal.But the profile
> >> that I have got is Tmax, Cmax,and AUC(the means and variances are
> >> already known),instead of Ka,CL,and V. What the $PK modification
> >> should I have to do in the model where the advan2 has been taken in
> >> the $subroutine.
> >>
> >> F=1.
> >>
> >> Any suggestion would be appreciated.
> >>
> >> Yours,ye hong bo
> >>
> >>
> >>
> >>
> >> --
> >> 工作和生活,都要开心的过.
> >> 你好,叶红波在此送上真挚的祝福.祝你开心,
> >> 叶红波
> >>
> >>
>
>
>
> --
> 工作和生活,都要开心的过.
> 你好,叶红波在此送上真挚的祝福.祝你开心,
> 叶红波
>
>
Received on Thu Apr 22 2010 - 14:45:02 EDT

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