Siwei,
Nonmem computes the time from the most recent dose (which is in the
past). It has no information about future doses, thus it cannot give you
negative values. If you know the inter-dose interval (12 hours?), you
can subtract it from TAD value to get the negative value (relative to
the reference dose that you would like to use).
Leonid
--------------------------------------
Leonid Gibiansky, Ph.D.
President, QuantPharm LLC
web: www.quantpharm.com
e-mail: LGibiansky at quantpharm.com
tel: (301) 767 5566
On 7/5/2012 12:16 PM, siwei Dai wrote:
Hi, Everyone:
I am having trouble with getting the correct output of TAD (time after
dose) and hoping to get your suggestions.
Here is a brief description of my dataset: drug was given multiple
dosing every 12 hours. All the dosing events were recorded in the input
file. Observations were taken right before the last dose (predose), and
0.5, 1, 2, 4, 8 hrs post-dose.
I have used this code to calculate the TAD
IF(AMT.GT.0) THEN
TDOS=TIME
TAD=0.0
ENDIF
IF (AMT.EQ.0) TAD=TIME-TDOS
In the output, the TADs calculated for the predose observation, instead
of being a negative value, are closed to 12 and larger than the one for
8 hrs observations. It is obviously wrong and it give me wrong
individual plots.
I tried to find useful information in NM archive but cannot find any
that suitable for my situation.
Any suggestions are greatly appreciated! Thank you in advance for your help!
Siwei
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