Re: simluation Tmax Cmax AUC

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" <[email protected] > <mailto:[email protected]>>Hi, > > > > >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 > >> > >> > >> > >> > >> -- > >> ??????????,????????????. > >> ????,????????????????????????.????????, > >> ?????? > >> > >> > > -- > ??????????,????????????. > ????,????????????????????????.????????, > ??????