Steady state: Cmin / PTF [NCA / SHAM]

posted by Helmut Homepage – Vienna, Austria, 2012-02-06 13:24  – Posting: # 8062
Views: 6,415

Hi Simon!

» The predicted Clast is extractable from the Summary table; here's a simple example with an Inner Join. See how sample time is JOINED AS Tlast, so obviously only truly appropriate where Tlast=Tau.

Nice method. Incomplete, isn’t it?
You need to sort also on Formulation and Period, map Clast to Source Column of Worksheet 1, map Sequence to Source Column in one of the worksheets, set Inner Joint and edit cells B1 and B5 of the Sort Map from …
  Worksheet 1 Sorts  Worksheet 2 Sorts
1 Tlast
2 Subject            Subject
3 Period             Period
4 Formulation        Formulation
5                    Time

… to
  Worksheet 1 Sorts  Worksheet 2 Sorts
1 Tlast              Time
2 Subject            Subject
3 Period             Period
4 Formulation        Formulation


Unfortunately tlast in a cross-over multiple dose study (at least in the first period) τ; the last sample is generally taken 5–10 minutes before the next administration. I would suggest using one of two methods (see here, slides 35, 48–50). Personally I prefer method (1); method (2) is PHX/WNL’s method in the calculation of AUCτ. Note that if the last sample was taken exactly at τ (f.i. in the second period), no correction will be done by both methods (i.e., the estimated Cmin = Clast and AUCτ = AUClast), since the time difference = 0 and ℯ0 = 1.

Cheers,
Helmut Schütz
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