NONMEM Users Network Archive

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Re: Time after dose

From: Leonid Gibiansky <LGibiansky>
Date: Thu, 05 Jul 2012 16:50:47 -0400

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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Received on Thu Jul 05 2012 - 16:50:47 EDT

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