It might be helpful if you could show some of the data records. I am guessing it has something to do with the units of conc and dose. You can also simulate PK with your initial guesses and overlay on your data to see if these guesses are even reasonable to begin with or not ?
Best Jeet Sent from my iPhone On Mar 5, 2011, at 12:02 PM, Susan Al taher <[email protected]> wrote: > Hi > > I am trying to build a structural model for an oral drug. I am getting > extremely large and unreasonable values for vd, eg a billion L, putting an > upper limit on theta will give a near boundary warning. > > Does anyone have an idea why this might occur and how to solve it. > > This is part of the input file: > $SUBROUTINE ADVAN2 TRANS2 > $PK > TVCL = THETA(1) > CL = TVCL*EXP(ETA(1)) > V = THETA(2) > KA = THETA(3) > S2 = V > > > $THETA (0,10) > $THETA (0,20) > $THETA 2 FIXED > > > Best regards > Susan
