Re: lagged concentrations
From: BellyGom@aol.com
Subject: Re: [NMusers] lagged concentrations
Date: 10/29/2003 4:18 PM
Dear Leonid,
Thank you so much for your interest in the problem; hope that
I will describe it a little better this time.
Actually the entire control stream will be too confusing and
the PD part of the corresponding PKPD model is not at all
related to the problem; so I put only the PK bit (all PK
parameters are fixed to the values obtained from a separate
PK analysis).
Basically I have a perfectly working zero-order one
compartment PK model without an error. But now I need
two more concentration estimates from two different time
points (consequently require two more compartments):
C(t) : compartment 1/V
C(t-theta(1)) : compartment 2/V
C(t-theta(2)) : compartment 3/V
The following code should ideally had given me lagged dose
amount estimates A(2), A(3); in particular A(2) should had
been basically A(1), time lagged by theta(1). But unfortunately
the value of A(2) stays zero regardless of time. Note that I
did not initialise compartment 2 and 3 since the corresponding amount
should be 0 at the beginning anyway.
$PROBLEM ~~
$INPUT ID TIME DV AMDT MDV CMT ~~
$DATA ~
$SUBROUTINES ADVAN6 TOL=5
$MODEL
COMP=1
COMP=2
COMP=3
$PK
CALLFL=-2
CL = THETA()
V = ()
S1 = V
S2 = V
S3 = V
K = CL/V
ALAG2 = THETA()
ALAG3 = THETA()
$DES
DADT(1) = -K*A(1)
DADT(2) = -K*A(2)
DADT(3) = -K*A(3)
C1=A(1)/S1
C2=A(2)/S2
C3=A(3)/S3
So help!
Sincerely,
In-Sun Nam