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sinhmar ☆ India, 2009-02-11 12:20 (6332 d 07:21 ago) Posting: # 3221 Views: 5,781 |
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Dear Helmut and D_Labes, I have read your discussion on SAS and Winnonlin codes and results for scaled average bioequivalence in this discussion and it was very helpful for me. So in SAS and Winnonlin outputs we are getting variance for both test and reference while we are repeating only reference as per our design. So my question is how are we getting the variance for Test and can we use that variance of reference for scaling purpose in the study or there is some problem with the SAS codes? Regards, Sinhmar |
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d_labes ★★★ Berlin, Germany, 2009-02-11 13:41 (6332 d 06:00 ago) @ sinhmar Posting: # 3223 Views: 4,849 |
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Dear Sinhmar, ❝ [...] So in SAS and Winnonlin outputs we are getting variance for both test and reference while we are repeating only reference as per our design. ❝ So my question is how are we getting the variance for Test [...] At my present knowledge it is not totally clear for me, how SAS (with the SAS code given in the mentioned thread) and WinNonlin are calculating the variance components of the intra-individual variabilities for the test and reference formulations. My feeling  is that there is a problem with the model formulation within both software. An indication for that is that both came out with different values for the model parameters (especially intra- and inter-subject variabilities).Thus I would go for the moment with the so called "Method of moments" in evaluating scaled ABE. The necessary formulas for estimating the intra-individual variability of the reference and the estimator of the difference between test and reference for the extra-reference design can be found in R.J. McNally Tests for Individual and Population Bioequivalence Using 3-Period Crossover Designs which can be found online here. This paper deals indeed with individual BE but can puzzled together with the paper of Haidar et.al. to evaluate scaled ABE. Haidar et.al. Bioequivalence Approaches for Highly Variable Drugs and Drug Products Pharmaceutical Research 25/1, 237-241 (2008) free online resource here Hope this helps. See also this thread. — Regards, Detlew |
Ing. Helmut Schütz