Re: Is “DOSE=0” accepted by NONMEM?
Zheng,
If you have only subjects with unknown dosing history, one can assume mono-exponential decay (provided that the data do not contradict this assumption: can be checked by plots of DV vs TIME in semi-scale). With this assumption, one can use
$PRED
C0 = THETA(1)*EXP(ETA(1)) ; initial value
K = THETA(2)*EXP(ETA(2)) ; rate of decay
TY = C0*EXP(-K*TIME) ; individual prediction
Y = TY*(1+EPS(1)) ; proportional error model
Leonid
--------------------------------------
Leonid Gibiansky, Ph.D.
President, QuantPharm LLC
web: www.quantpharm.com
e-mail: LGibiansky at quantpharm.com
tel: (301) 767 5566
Quoted reply history
On 9/7/2015 2:30 AM, Zheng Liu wrote:
> Dear NONMEM users,
>
> I have a group of patients, whose plasma drug levels are measured and
> known at time=0 (no further drug is given to the patients afterwards.).
> I try to know, after how long time the drug will be completely cleared
> out from these patients. Naturally I used NONMEM to fit the patients' V
> and CL, in order to get plasma concentration change profile.
>
> However seems NONMEM only accepts DOSE is a positive number. If DOSE=0,
> NONMEM can't perform the fitting. Can anyone kindly give me some
> suggestions to solve this problem? Thanks a lot in advance!
>
> PTID DV AMT time EVID
> 2 . 0
> 0 1
> 2 6.8 0 0 0
> 2 1.1 0 3 0
> 2 0 0 6 0
> 3 . 0 0 1
> 3 1.08 0 0 0
> 3 0.16 0 3 0
> 3 0.03 0 6 0
> 3 0 0 9 0
>
> Zheng