Diagnostics

Hi Some things to consider: - does your data support non-linear kinetics (perhaps all your actual data are within the "linear" range of your MM kinetics)? - are your estimates of Vmax and Km correlated? - what about the estimates of IIV on Vmax and Km? Are they realistic? Sebastien fakrudeen ali ahamed wrote: > Dear All, > > I am trying to develop a pop pk model for my data. > my compound follows MM kinetics. > Pls find my control stream below. > > $PROBLEM Pop pk modeling > ;UNITS: TIME=h (h),CONCENTRATION=MG/L > ;Vmax= µg/h, KM = µg/mL, VOLUME = L > ;DOSE = MG > > $DATA Pheny.csv IGNORE=# > > $INPUT ID TIME DV MDV DVID AMT WT AGE SEX LFT > > $SUBROUTINE ADVAN6 TRANS1 TOL=9 > > $MODEL > COMP=CENTRAL > > $PK > > Vmax=THETA(1)*EXP(ETA(1)) ;MAXIMUM RATE OF ELIMINATION > > KM = THETA(2)*EXP(ETA(2)) ;CONC AT 50% Vmax > > V =THETA(3)*EXP(ETA(3)) ;VOLUME OF DISTRIBUTION IN L > > S1=V > > $DES > > CP=A(1)/S1 > > DADT(1)=-Vmax*CP/(KM+CP) ;UNITS OF VMAX = µg/h > > $ERROR > > Y=F+F*ERR(1)+ERR(2) > IPRED=F > > $THETA (1,5) ;POPVMAX > > $THETA (1,2) ;POPKM > > $THETA (1,5) ;POPV > > $OMEGA 0.04 ;BSVVMAX > > $OMEGA 0.04 ;BSVKM > > $OMEGA 0.09 ;BSVV > > $SIGMA 0.02 ;ERRCV > > $SIGMA 0.1 ;ERRSD > > $ESTIMATION METHOD=1 INTERACTION MAXEVALS=9990 PRINT=5 POSTHOC > > $COVARIANCE MATRIX=S > > $TABLE ID AMT TIME DV MDV NOPRINT ONEHEADER FILE=mytab1 > $TABLE ID TIME DV IPRED NOPRINT ONEHEADER FILE=sdtab1 > $TABLE ID TIME DV NOPRINT ONEHEADER FILE=patab1 > $TABLE ID AGE WT AMT NOPRINT ONEHEADER FILE=cotab1 > $TABLE ID NOPRINT ONEHEADER FILE=catab1 > > The run was successful but am getting some unrealistic km value;also am not able to get the diagnostics plots. > > Any guidance or suggestions would be highly appreciated. > > Regards > Dr.N.FAA > > < http://sigads.rediff.com/RealMedia/ads/click_nx.ads/www.rediffmail.com/signatureline.htm@Middle ?> > > Follow *_Rediff Deal ho jaye! < http://track.rediff.com/click?url=___ http://dealhojaye.rediff.com?sc_cid=rediffmailsignature___&cmp=signature&lnk=rediffmailsignature&newservice=deals >_* to get exciting offers in your city everyday.

Dear Dr. N.FAA, You supply insufficient information about your problem. In order to get useful answers I suggest that you first answer the following questions. 1. What is the nature of your study/experiment? 2. In what way is the estimated KM value unrealistic? 3. You state that you are “not able to get the diagnostics plots”. Do you mean that mean that no table files are generated? If so, what error messages are returned by NONMEM? Kind regards, Martin Bergstrand, PhD Pharmacometrics Research Group Dept of Pharmaceutical Biosciences Uppsala University, Sweden Postal address: Box 591, 751 24 Uppsala, Sweden Phone +46 709 994 396 Fax + 46 18 4714003