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| TDM EXAMPLE |
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This is an example of how F1 can be used to simplify the preparation
of a data file when the dose is changed often, e.g., for Therapeutic
drug monitoring (TDM).
Suppose the dosing pattern is consistent (e.g., every 12 hours) but
the amount changes often. Suppose also there are observation events
at various times.
In the following data set, there is only one dose record having AMT=1.
ADDL and II are used to specify an (effectively infinite) number of
additional doses, every 12 hours. When the dose amount changes, it is
sufficient to supply a record giving the new dose amount in the DOSE
data item. Such records have EVID=2. There is no need to interrupt
the dosing pattern for an observation event, or to count the number of
doses between observation events.
Suppose a fragment of the dose records looks like this:
ID DAT1=DROP TIME EVID DV DOSE AMT II ADDL
1 01.01.2008 20 1 0 4 1 12 99999
1 03.01.2008 8 0 6.1 0 0 0 0
1 04.01.2008 8 0 7.6 0 0 0 0
1 04.01.2008 20 2 0 3 0 0 0
1 06.01.2008 8 0 5.4 0 0 0 0
Here is a fragment of the control stream:
$INPUT ID DAT1=DROP TIME EVID DV DOSE AMT II ADDL
...
$PK (ADDITIONAL OR LAGGED)
...
IF (DOSE> 0) SAVEDOSE=DOSE
F1=SAVEDOSE
In $PK, the value of DOSE is saved, and used on subsequent calls to PK
as the value of F1. Although F1 is usually used to model the bio-
availability of doses to compartment 1, in this example it is the
actual dose amount.
REFERENCES: Guide V Section 7.4.4
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