$DES : Initialising the value of A at time 0
From:"LSEN (Lars Erichsen)"
Subject:[NMusers] $DES : Initialising the value of A at time 0
Date:Tue, 29 Oct 2002 10:16:31 +0100
Dear nmusers,
I have been puzzled by unexpected initial values (at time 0) of A(1) from
the NM code below.
The NM data set contains no dosing information, so I would expect A(1) to be
0 at time 0 but
instead the value at time 0 is = the value at 24 h (last time point) for the
same subject.
Can someone explain this to me?
Thanks in advance,
Lars Erichsen
Novo Nordisk
NM-code:
$PROBLEM indirect response model
$INPUT ID STDY DAY TIME PKK GIR DOSE CONC DV DELF
DELB DTF DTB DBGF DBGB
$DATA dataset.prn IGNORE=C
$SUBROUTINES ADVAN6 TOL 5 DP
$MODEL
COMP=(CENTRAL,DEFOBS,DEFDOSE)
$PK
TVEMAX=THETA(1)
EMAX=TVEMAX
TVEC50=THETA(2)
EC50=TVEC50*EXP(ETA(3))
TVKOUT=THETA(3)
KOUT=TVKOUT*EXP(ETA(2))
TVV=THETA(5)
V=TVV
TVPOTE=THETA(6)
POTE=EXP(TVPOTE)
TVBASE=THETA(8)
IF (STDY.EQ.2) TVBASE=THETA(9)
BASE=TVBASE
IF(STDY.EQ.1) EC50=POTE*EC50;
STIM=EMAX*PKK**2/(EC50**2+PKK**2)
$ERROR
IPRE=BASE+A(1)
Y=IPRE+ERR(1); Y IS NORMAL DISTRIB
$DES
A1=A(1)
DADT(1)=GIR/V-KOUT*(1+STIM)*A(1)
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