Bioequivalence and Bioavailability Forum • Ratio calculation of fully replicate study

Ratio calculation of fully replicate study [RSABE / ABEL]

posted by Helmut – Vienna, Austria, 2020-07-09 14:19 (1523 d 19:08 ago) – Posting: # 21662
Views: 4,852

Hi Mithu,

❝ ❝ Without knowing your SAS code it would be reading tea leaves.

❝

❝ We have used Progesterone program.

… which nowhere gives the subject’s T/R-ratios.

❝ ❝ $$x/y=\exp (\log_{e}x-\log_{e}y)\;\left\{x,y \in \mathbb{R}^{+} \right\}\; {\color{red}{\neq}}\log_{e}x/\log_{e}y$$

❝ Still I could not understand.

Calculating the ratio of logs (2. of your OP) is nonsense.
The individual averaged log-differences $I_{ij}$ (for subject $i$ in sequence $j$) are computed in the FDA’s SAS macro by

ilat=0.5*(lat1t+lat2t-lat1r-lat2r);

Simply back-transform them.

Let’s have a look at the EMA’s full replicate reference data set:

SUBJECT DATA FORMULATION PERIOD SEQUENCE logDATA 1 2285.96 R 1 BABA 7.734541 1 1955.82 T 2 BABA 7.578565 1 1345.94 R 3 BABA 7.204848 1 2856.24 T 4 BABA 7.957261

Then$$\overline{I_{11}}=0.5\times(7.578565+7.957261-7.734541-7.204848)=0.2982185$$and$$\overline{T_{11}/R_{11}}=\exp \overline{I_{11}}=\exp 0.2982185=1.347456$$Confirmed by Phoenix WinNonlin’s RSABE-template and my pocket calculator. :-D

Which leaves my second question open:

❝ ❝ Why on earth do you want to use Excel?

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Helmut Schütz

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Complete thread:

Ratio calculation of fully replicate study Mithu 2020-07-09 09:18 [RSABE / ABEL]
- Ratio calculation of fully replicate study Helmut 2020-07-09 10:51
  - Ratio calculation of fully replicate study Mithu 2020-07-09 11:23
    - Ratio calculation of fully replicate studyHelmut 2020-07-09 12:19
      - Ratio calculation of fully replicate study Mithu 2020-07-09 12:46
        
        Purpose? Helmut 2020-07-09 13:10
        
        Purpose? Mithu 2020-07-09 13:22
        
        Purpose? Helmut 2020-07-09 13:56
        
        Purpose? jag009 2020-07-09 18:01
        Purpose? Mithu 2020-07-10 08:00