simluation Tmax Cmax AUC

5 messages 3 people Latest: Apr 22, 2010

simluation Tmax Cmax AUC

From: Ye Hongbo Date: April 21, 2010 technical
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

Re: simluation Tmax Cmax AUC

From: Sebastien Bihorel Date: April 21, 2010 technical
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 > > -- > ??????????,????????????. > ????,????????????????????????.????????, > ??????

Re:Re: simluation Tmax Cmax AUC

From: Ye Hongbo Date: April 22, 2010 technical
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]>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 >> >> >> >> >> -- >> 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

Re: simluation Tmax Cmax AUC

From: Sebastien Bihorel Date: April 22, 2010 technical
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 > >> > >> > >> > >> > >> -- > >> ??????????,????????????. > >> ????,????????????????????????.????????, > >> ?????? > >> > >> > > -- > ??????????,????????????. > ????,????????????????????????.????????, > ??????

Re: simluation Tmax Cmax AUC

From: David Foster Date: April 22, 2010 technical
Hello, Perhaps this paper might be useful: C Dansirikul, M Choi, SB Duffull Computers in Biology and Medicine 35 (2005) 389 – 403 “Estimation of pharmacokinetic parameters from non-compartmental variables using Microsoft Excel”. Abstract: *** This study was conducted to develop a method, termed ‘back analysis (BA)’, for converting non- compartmental variables to compartment model dependent pharmacokinetic parameters for both one- and two-compartment models. A Microsoft ExcelJ spreadsheet was implemented with the use of Solver J and visual basic functions. The performance of the BA method in estimating pharmacokinetic parameter values was evaluated by comparing the parameter values obtained to a standard modelling software program, NON- MEM, using simulated data. The results show that the BA method was reasonably precise and provided low bias in estimating fixed and random effect parameters for both one- and two-compartment models. The pharmacokinetic parameters estimated from the BA method were similar to those of NONMEM estimation. *** I have employed the technique myself and found it to very useful. Regards, David
Quoted reply history
On 23/04/10 1:19 AM, "yhb5442387" <[email protected]> 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]>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 >> >> >> >> >> -- >> 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 David Foster, PhD Lecturer School of Pharmacy and Medical Sciences Playford Building Room P4-08 City East Campus University of South Australia Adelaide SA 5000 CRICOS Provider Number: 00121B Phone: +61 8 8302 2055 Fax: +61 8 8302 2389 Email: [email protected] Note: This message (including any attachments) is confidential and is intended only for the individual(s) named. If you have received it by mistake, please let the sender know by e-mail reply and delete it from your system. P Please consider the environment before printing this email