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| SS DATA ITEM |
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MEANING: Steady-State (SS) data item for PREDPP
CONTEXT: $INPUT record and NONMEM data set
USAGE:
$INPUT ... SS ...
DISCUSSION:
SS labels PREDPP's steady-state (SS) data item. The steady-state data
item is optional. It can take one of three values in any event
record.
0 indicates that the dose is not a steady state dose.
1 indicates that the dose is a steady state dose, and that the com-
partment amounts are to be reset to the steady-state amounts
resulting from the given dose. Compartment amounts resulting
from prior dose event records are "zeroed out," and infusions in
progress or pending additional doses are cancelled. The system
is not totally reset: the on/off status of the compartments
remains as it was at the time of the prior event record (if any),
and the value of time must be greater than or equal to its value
on the prior event record (if any).
2 indicates that the dose is a steady state dose and that the com-
partment amounts are to be set to the sum of the steady-state
amounts resulting from the given dose plus whatever those amounts
would have been at the event time were the steady-state dose not
given. I.e., letting t be the time on the event record, then the
amounts in the compartments are updated to amounts valid for time
t, and next, these amounts are added to the steady-state amounts.
This is meaningful when kinetics are linear and the superposition
principle holds.
3 indicates that the dose is a steady state dose. SS = 3 is iden-
tical to SS = 1 with one exception: with Steady State routines
SS6 and SS9, the existing state vector (compartment amounts and
eta derivatives) is used as the initial estimate in the computa-
tion of the steady-state amounts. The user supplies the initial
estimate with some combination of prior event records, e.g.,
reset, transient dose, and other-type event records.
When the SS data item is used, one or more of the data items AMT,
RATE, and II must be present in the event record to specify the steady
state dosing pattern.
REFERENCES: Guide VI Section V.F
REFERENCES: Guide V Section 6.8
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