RE: PD interaction between two substances
From: Bachman, William (MYD) bachmanw@iconus.com
Subject: RE: [NMusers] PD interaction between two substances
Date: Mon, April 5, 2004 9:15 am
Johan,
Do I understand your question correctly: "how do I fit simultaneously PK and
PD data simultaneously if I have two different PK observations and one PD
observation?".
If so, you have to structure your model so that each observation is modeled
in a different compartment. Then instead of a binary switching mechanism
based on the CMT data, you have to construct a switch based on three
compartments. There may be some nuances I have not considered, but,
basically:
$ERROR
;IF CMT=1 for C(1), CMT=2 for C(2), CMT=3 for Effect
C1=A(1)/V1
C2=A(2)/V2
IF (CT.EQ.3) THEN
Y=Emax *(1/(1 + EC51/C1)* (1 + C2/EC52) + 1/(1 + EC52)/(C2) * (1 + C1/EC51))
+ ERR(3)
ELSEIF (CMT.EQ.1) THEN
Y =F*EXP(ERR(1)) ;F is pred in CMT 1 here
ELSE
Y =F*EXP(ERR(2)) ;F is pred in CMT 2 here
ENDIF
;check for typos in above
Bill
William J. Bachman, Ph.D.
Manager, Pharmacometrics Research and Development
GloboMax
The Strategic Pharmaceutical Development Division of ICON plc
7250 Parkway Drive, Suite 430
Hanover, MD 21076
410-782-2212
bachmanw@iconus.com