Mike,
You could use a MIXTURE model to determine of the 1-hour nominal time point is before or after the infusion.
$PK
CALLFL=1
EST=MIXEST
IF (MIXNUM.EQ.2) THEN
D1 = THETA(1)
ELSE
D1=THETA(2)
ENDIF
...
$MIX
P(1)=THETA(3)
P(2)=1.-THETA(3)
NSPOP=2
...
$THETA (0.9 FIXED) ; Duration of Infusion for Population #1
(1.1 FIXED) ; Duration of Infusion for Population #2
(0 0.5 1) ; Proportion of Population having sampled in infusion phase.
Quoted reply history
From: owner-nmusers
Behalf Of mdkzone
Sent: Thursday, June 02, 2011 10:45 AM
To: nmusers
Subject: [NMusers] Modeling concentration data with imprecise sampling time
All:
I have a data set following a constant rate 1-hour infusion where the time of 1-hour sample is imprecise. In some cases the "1-hr" sample was taken prior to infusion termination as it was intended; however, in others it was quite apparently take after the infusion ended. I'm thinking of modeling with the time of the "1-hr" sample as a "theta". Does anyone have a NONMEM coding example showing how to do this? Any other suggestions as to how to handle this would be appreciated as well.
Thanks,
Michael
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