[R-sig-dyn-mod] Simecol - simulating a pk model with multiple oral doses

Nicholas Lewin-Koh nikko at hailmail.net
Wed Oct 13 17:16:06 CEST 2010


Hi Thomas,
If I had known about the list I would have started here. It would help
if it
were listed at http://www.r-project.org/mail.html

I think events will do what I want. The model is
dCp = (1/V)*Ka*F*D*exp(-Ka*t)- Ke*Cp
dTV = Gc*TV - Kr*Cp*TV

Cp is the drug concentration in plasma 
TV is the tumor volume
D is the oral dose of the drug, given at t0,tdi,t2*di, ..., tn*di
where di is the dosing interval

So in the solution the integral of Cp is evaluated over all previous
doses each
with the appropriate lag. I'll give it a try.

Nicholas



On Wed, 13 Oct 2010 11:03 +0200, "Thomas Petzoldt"
<thomas.petzoldt at tu-dresden.de> wrote:
> Hi Nicholas,
> 
> hmm, I don't understand yet exactly what you mean, so here are a few
> ideas:
> 
> - dosing in PK models can be easily implemented by using the "events" 
> mechanism available in recent versions of deSolve:
> 
> library(deSolve)
> ?events
> 
> - a few examples may also be found in the R-SIG-Dynmod mailing list.
> 
> It is in general a good idea to post questions there, so that we get an 
> archive of possible solutions and some discussion culture. I'm still a 
> little bit optimistic that also others participate in answering 
> questions, so it may help if you address the questions to all list 
> members and not explicitly to me ;-)
> 
> - it is possible to nest simecol models, at least in principle. However, 
> nesting is not yet possible for all the deSolve solvers, because most of 
> the codes (from ODEPACK) make use of global variables.
> 
> In contrast, solvers of the "rk" family can be nested, so you may use 
> either lsoda (or similar) with one rk solvers or nest several rk.
> 
> 
> Can you tell me (or the list) a few more details about your problem?
> 
> Thomas Petzoldt
> 
>



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