From: "Abouel Leil, Tarek M. Ph.D." AbouelLeil.Tarek@mayo.edu Subject: [NMusers] NONMEM Modeling of Plasma + Urine Data Date: Tue, 21 Nov 2006 09:37:00 -0600 Hello, I am trying to simultaneously model the PK of a drug and its metabolite using NONMEM. I have plasma observations for the parent compound (17-AAG) and the metabolite (17-AG). I also have 24hr urine collection data for both compounds. When I tried to model this using ADVAN7 in NONMEM, it stops almost immediately with the following error: MONITORING OF SEARCH: 0PRED EXIT CODE = 1 0INDIVIDUAL NO. 1 ID=0.10100000E+03 (WITHIN-INDIVIDUAL) DATA REC NO. 4 THETA= 1.43E+04 2.42E+04 8.44E+04 8.96E+04 1.24E+04 2.13E+04 5.00E+04 NUMERICAL DIFFICULTIES OBTAINING THE SOLUTION. THE COEFFICIENT MATRIX IS ALGORITHMICALLY SINGULAR. 0PROGRAM TERMINATED BY OBJ MESSAGE ISSUED FROM ESTIMATION STEP AT INITIAL OBJ. FUNCTION EVALUATION 1THERE ARE ERROR MESSAGES IN FILE PRDERR 2006.11.20.1820.57 Here is the NONMEM control stream that I am using: $INPUT ID AMT EVID RATE TIME DV UVOL CMT BW BSA SEX AGE CRCL BR AP AST DOSE $DATA ..\data.dta IGNORE=# $SUBROUTINE ADVAN7 $MODEL COMP=(CENTRAL, DEFDOSE, DEFOBS) COMP=PERIPH COMP=METAB COMP=("URINE", NODOSE, INITIALOFF) COMP=("METABUR", NODOSE, INITIALOFF) $PK TVCL = THETA(1) CL = TVCL*EXP(ETA(1)) TVV = THETA(2) V = TVV * EXP(ETA(2)) K14 = CL/V S1 = V TVQ = THETA(3) Q = TVQ * EXP(ETA(3)) TVV2 = THETA(4) V2 = TVV2 * EXP(ETA(4)) K12 = Q/V K21 = Q/V2 TVCLM = THETA(5) CLM = TVCLM * EXP(ETA(5)) K13 = CLM/V TVCLMO = THETA(6) CLMO = TVCLMO * EXP(ETA(6)) TVV3 = THETA(7) V3 = TVV3 * EXP(ETA(7)) K35 = CLMO/V3 S3 = V3 S0=UVOL $ERROR ASY1=0 IF (CMT.EQ.1) ASY1=1 ASY2=0 IF (CMT.EQ.3) ASY2=1 ASY3=0 IF (CMT.EQ.4) ASY3=1 IPRED = F W = 1 IF (F.EQ.0) W=1 IRES = DV-IPRED IWRES = IRES/W Y=IPRED+ASY1*ERR(1)+ASY2*ERR(2)+ASY3*ERR(3)+(1-ASY1)*(1-ASY2)*(1-ASY3)*ERR(4) $THETA (0,14300.,) ; TVCL $THETA (0,24200.,) ; TVV $THETA (0,84400.,) ; TVQ $THETA (0,89600.,) ; TVV2 $THETA (0,12400.,) ; TVCLM $THETA (0,21300.,) ; TVCLMO $THETA (0,50000.,) ; TVV3 $OMEGA 0.25 ; ETATVCL $OMEGA 0.25 ; ETATVV $OMEGA 0.25 ; ETATVQ $OMEGA 0.25 ; ETATVV2 $OMEGA 0.25 ; ETATVCLM $OMEGA 0.25 ; ETATVCLMO $OMEGA 0.25 ; ETATVV3 $SIGMA 100 ; ERRSD17AAG $SIGMA 100 ; ERRSD17AG $SIGMA 100 ; ERRSD17AAG URINE $SIGMA 100 ; ERRSD17AG URINE $EST METH=0 MAXEVAL=9999 NOABORT POSTHOC PRINT=5 SIGDIGITS=5 $COVARIANCE The data file looks like this: #ID AMT EVID RATE TIME DV UVOL CMT 101 31500000 1 31500000 0 0 0 1 101 0 2 0 0 0 0 4 101 0 2 0 0 0 0 5 101 0 0 0 0.5 20 0 3 101 0 0 0 0.5 231 0 1 101 0 0 0 0.92 51 0 3 101 0 0 0 0.92 300 0 1 101 0 0 0 1.08 47 0 3 101 0 0 0 1.08 146 0 1 101 0 0 0 1.25 40 0 3 101 0 0 0 1.25 109 0 1 101 0 0 0 1.5 55 0 3 101 0 0 0 1.5 121 0 1 101 0 0 0 2 42 0 3 101 0 0 0 2 119 0 1 101 0 0 0 3 25 0 3 101 0 0 0 3 75 0 1 101 0 0 0 5 17 0 3 101 0 0 0 5 25 0 1 101 0 0 0 9 0 0 1 101 0 0 0 9 0 0 3 101 0 0 0 17 0 0 1 101 0 0 0 17 0 0 3 101 0 0 0 24 1993.956 904 -4 101 0 0 0 24 609.6032 904 -5 I was able to model the above data without urine observations, so I feel there must be something wrong with the way I am coding the urine compartments. I would really appreciate any advice. Thanks, Tarek A. Leil, Ph.D. Department of Oncology, Guggenheim 1311 Mayo Clinic 200 First Street SW Rochester, MN 55905 ph: 507-538-4227 fax: 507-266-5146 pgr: 08189 _______________________________________________________ From: "Nandy, Partha [PRDUS]" PNandy@prdus.jnj.com Subject: RE: [NMusers] NONMEM Modeling of Plasma + Urine Data Date: Wed, 22 Nov 2006 19:23:38 -0500 Hi Tarek, I am assuming that the drug is given as an infusion from the "RATE" column in your data file. You mentioned that you ran the model with just the parent & metabolite data in plasma. Did you use ADVAN7 for that as well? The formation of metabolite is not well defined..Is it a saturable process? If so, Km and Vmax should be implemented. Also, TVCL is total clearance as shown below: TVCL = THETA(1) CL = TVCL*EXP(ETA(1)) So, it is not clear how the following is implemented.. TVCLM = THETA(5) CLM = TVCLM * EXP(ETA(5)) Usually Total Clearance is modeled as CL=CLRenal + CLMetab Just quickly browsing through the data I do not see rate being declared in your control file as R1=RATE. Curious about how the RATE was specified in the control file when the parent & metab concentration in plasma was modeled. I also see that V1 and V3 was scaled but not V2. Your error structure is quite complex. It is not clear to me what the purpose of ERR(4) is. Also your initial conditions for SIGMA seems to be very high! Typically the ERROR could be modeled as (There are many ways to do this..). I1=0 I2=0 I3=0 I4=0 IF (CMT.EQ.1) I1=1 IF (CMT.EQ.3) I2=1 IF (CMT.EQ.4) I3=1 IF (CMT.EQ.5) I4=1 Y=IPRED + I1*ERR(1) + I2*ERR(2) + I3*ERR(3) + I4*ERR(4) Instead of just additive model, did you try other ERROR models for e.g. ADD+PROP etc? Hope this helps. Partha _______________________________________________________