Re: NONMEM
From: Justin Wilkins justin.wilkins@farmbio.uu.se
Subject: Re: [NMusers] NONMEM
Date: Thu, 14 Sep 2006 13:40:08 +0200
Dear Ritu,
The example you quote seems to be more suitable for producing a limited
series of Monte Carlo simulations than for producing a truly optimal
design. If you want to do it in the most appropriate way, you will need
to use a tool designed specifically for the purpose.
You will have to decide what your needs are (whether you need exact
sampling times or sampling windows, which will inform your choice of
approach - D- or ED-optimality, for example), and then select one of the
several pieces of software available based on these requirements. Two
that are commonly used for generating population designs are
PopED - http://depts.washington.edu/rfpk/rd/software_popED.html
PFIM - http://www.bichat.inserm.fr/equipes/Emi0357/download.html
Each (there are others as well) has its own strengths and weaknesses but
I have used PopED with some success in the past, and PFIM has a good
reputation. Both packages require other software to run - PopED needs
O-Matrix or Matlab, and PFIM needs R or S-PLUS. Both rely on
minimization of the inverse of the Fisher information matrix with
respect to some variable (time, in your case), but others on this group
will probably be able to give you more detail about this than I can.
$SUPER is a NONMEM control record used to program a series of problems
for NONMEM to perform within a single file.
As for the other NONMEM parameters you mention, EVID is the PREDPP event
identification variable, is usually required, and has 5 possible values
- 0 for observation events, 1 for dose events, 2 for 'other-type' events
such as compartment resets, 3 for reset events (which re-initialize the
PK kinetic system) and 4 for reset-and-dose events (a combination of 1
and 3).
SS is the steady-state data item for PREDPP, and can have 4 possible
values - 0, indicating that the dose is not a steady-state dose, 1,
indicating a steady-state dose with reset, 2, indicating steady-state
dose without reset, and 3, which is very similar to 1.
The above is a (very) basic summary from the NONMEM online help, which
is accessed by the commands
>> nmhelp SUPER
>> nmhelp EVID
>> nmhelp SS
from the command prompt. Have a look for more detail.
COVA and RATD have no special meaning in NONMEM and appear to have been
user-defined variables (covariates, perhaps) supplied by the author of
the quoted code.
Justin