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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 ident-
      ical  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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