RE: VD as a fraction of another VD
Dear Nick,
I want to try a previously reported PK model (Knibbe et al. Clin Pharmacokinet
2009; 48 (6): 371-385) to fit data similar to mine of morphine and its
metabolites in which the volumes of distribution of metabolites were estimated
as a fraction of volume of parent drug what seems to show good estimates. But
also probably I´ll try to estimate the volumes of metabolites as separate
parameters THETA with its corresponding variabilities, do you have any other
suggestions?, thank you.
And thanks also to Bill and Rob.
Kind regards,
Orlando.
PhD student Carlos Orlando Jacobo Cabral
Departamento de Farmacología, Lab.34
Centro de Investigación y de Estudios Avanzados del I. P. N.
Email: [email protected]; [email protected]
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> Date: Mon, 21 May 2012 22:12:18 +0200
> From: [email protected]
> To: [email protected]
> Subject: Re: [NMusers] VD as a fraction of another VD
>
> Carlos,
> Why? What pharmacological or physiological reason would lead you to want
> to fix the volume of a metabolite to be a fraction of the parent?
> Nick
>
Quoted reply history
> On 21/05/2012 8:19 p.m., Carlos Orlando Jacobo Cabral wrote:
> > Dear NMusers,
> >
> > Hi, I have data of a parent drug (intravenously administered) and its
> > metabolite, ¿How can I code the volume of distribution of metabolite
> > as a fraction of the central volume of parent?
> > An example of the model that I want to fit is:
> >
> > $PK
> >
> > V1=THETA(1)*EXP(ETA(1)) ; Central Volume of parent
> > V2=THETA(2)*EXP(ETA(2)) ; Peripheral Volume of parent
> > Q=THETA(3) ; intercompartmental clearance
> >
> > V3= ???????????? ; Volume of metabolite as a fraction of V1 with
> > variability
> >
> > CL1=THETA(5)*EXP(ETA(4)) ; Formation clearance of metabolite
> > CL2=THETA(6)*EXP(ETA(5)) ; Elimination clearance of metabolite
> > CL0=THETA(7)*EXP(ETA(6)) ; Parent drug excretion by routes other than
> > formation of metabolite
> >
> >
> >
> > - Thank you in advance.
> >
> > Orlando.
> >
> > /P//hD //student/ Carlos Orlando Jacobo Cabral
> >
> > Departamento de Farmacología, Lab.34
> >
> > Centro de Investigación y de Estudios Avanzados del I. P. N.
> >
> > Email: [email protected] <mailto:[email protected]>;
> > [email protected] <mailto:[email protected]>
> >
>
> --
> Nick Holford, Professor Clinical Pharmacology
>
> First World Conference on Pharmacometrics, 5-7 September 2012
> Seoul, Korea http://www.go-wcop.org
>
> Dept Pharmacology& Clinical Pharmacology, Bldg 505 Room 202D
> University of Auckland,85 Park Rd,Private Bag 92019,Auckland,New Zealand
> tel:+64(9)923-6730 fax:+64(9)373-7090 mobile:+64(21)46 23 53
> email: [email protected]
> http://www.fmhs.auckland.ac.nz/sms/pharmacology/holford
>
>
>