From: Suzette Blanchard <suzette@sdac.harvard.edu>
Subject:[NMusers] initial condition model
Date: 7/24/2003 8:25 PM

Greetings,

	Could someone help me with how to set
up an initial condition - one compartment
model with first order absorption (i.e. a recursive
one compartment model with first order absorption
that would allow a random effect on the initial
concentration) in NONMEM?

	Thank you,
	Suzette

=================================
Suzette Blanchard, Ph.D.
Research Scientist
Frontier Science Foundation
1244 Boylston St. Suite 303
Chestnut Hill, MA 02467
Email:  suzette@sdac.harvard.edu
Phone:  (617) 632-2007
Fax:    (617) 632-2001
_______________________________________________________

From: Lewis B Sheiner <lewis@c255.ucsf.edu>
Subject: Re: [NMusers] initial condition model
Date: 7/25/2003 2:14 PM

Suzette,

You seem to want an intial condition on the state vector, in
which case the usual trick is to put a unit 'dose' into the
central compartment at time zero, associated with a value of
F for that compartment (and for time 0 only) which equals a
(new) theta plus a (new) eta
(see http://www.cognigencorp.com/nonmem/nm/99oct052000.html
for an extended discussion).

However, in the spirit of the approach & discussion at
http://www.cognigencorp.com/nonmem/nm/99apr022003.html, 
you might instead set F for the 'initializing' dose equal
to the observed (individual-specific) baseline concentration
value times V, plus a (new) eta whose variance is constrained
to equal that of the observation error.

LBS. 
-- 
   _/  _/  _/_/ _/_/_/ _/_/_/ Lewis B Sheiner,MD (lbs@c255.ucsf.edu)
  _/  _/ _/    _/     _/      Professor: Lab. Med., Biophmct. Sci.
 _/  _/ _/    _/_/_/ _/_/     Mail:    Box 0626, UCSF, SF,CA,94143
_/  _/ _/        _/ _/        Courier: Rm C255,521 Parnassus,SF,CA,94122
_/_/   _/_/ _/_/_/ _/         415-476-1965 (v), 415-476-2796 (fax) 
_______________________________________________________