RE: ADVAN6 coding question
From: "Serge Guzy" GUZY@xoma.com
Subject: RE: [NMusers] ADVAN6 coding question
Date: Sat, 25 Mar 2006 13:58:35 -0800
Hi Garry
This model should have the initial conditions in the B-cell compartment:
t=0, B=K03/K30
This assumes that at =0, you are at steady state and no drug yet enter the B-cell compartment:
Therefore:
DBDT = K03 - B*K30 -(VM2*A(1)*B)/(KM+A(1))=0 and A(1)=0
Then, K03-B*K30=0, Therefore, t=0, B=K03/K30
This model is by the way available as a part of the PK/PD libraries in the PDX-MC-PEM
program (model name is model56pd).
The differential equations are written below for the generalized (up to 3) non linear
compartment model linked to the indirect response model you want.
Serge Guzy
President POP-PHARM
SUBROUTINE fcn56pk (N, T, Y, YPRIME)
C SPECIFICATIONS FOR ARGUMENTS
IMPLICIT real*8 (A-H,O-Z)
REAL*8 T, Y(N), YPRIME(N)
REAL*8 K10,K12,K21,K01,KA,K13,K31,KM,K42
REAL*8 KIN,KOUT,IC50
REAL*8 TOL
C WE PASS THE VALUE OF THE INDEPENDENT VARIABLE (TSAMPLING(I,J))
COMMON/PKINFO/KIN,KOUT,IC50,EC50,EMAX,K10,K12,K21,K01,KA,K13,
1 K31,TLAG,F,KM,VMAX,V,V2,V3,V4,Q,K42,DK42,raterv
COMMON/TOTALRATE/SUMRATE
COMMON/LINEAR/LIN
C IF NON LINEAR pk, not parallel, then lin=2 and k10=0
IF(LIN.EQ.2)THEN
K10=0
ENDIF
CONTINUE
C
C C WILL BE OBTAINED FOR EACH T VALUE FROM MNODEL_SELECTION_PK_DIFF
CORAL EQUATION
C IF K01 IS ZERO, THEN WE FORCE YPRIME(1) TO BE ZERO
IF(K01.EQ.0)THEN
YPRIME(1)=0
ELSE
YPRIME(1)=-K01*Y(1)
ENDIF
C BLOOD: ORAL INPUT, K10 OUTPUT, K12 OUTPUT, K21INPUT
C K13 OUTPUT, K31 INPUT, SATURATED CLEARANCE OUTPUT
C IF VMAX =0, THEN WE ARBITRARILY PUT KM=1 TO PREVENT 0/0
IF(VMAX.EQ.0)THEN
KM=1
ENDIF
YPRIME(2)=K01*Y(1)*F-K10*Y(2)-K12*Y(2)+K21*Y(3)-K13*Y(2)+K31*Y(4)
1 -VMAX*Y(5)*Y(2)/(Y(2)+KM*V)+SUMRATE
IF(K12.EQ.0.AND.K21.EQ.0)THEN
YPRIME(3)=0
ELSE
YPRIME(3)=K12*Y(2)-K21*Y(3)
ENDIF
IF(K13.EQ.0.AND.K31.EQ.0)THEN
YPRIME(4)=0
ELSE
YPRIME(4)=K13*Y(2)-K31*Y(4)
ENDIF
YPRIME(5) = KIN-KOUT*Y(5)-EMAX*Y(5)*Y(2)/(EC50*V+Y(2))
CONTINUE
RETURN
END
_______________________________________________________