Sereng ☆ USA, 20201022 22:30 (1364 d 05:16 ago) Posting: # 22047 Views: 3,579 

Dear colleagues, Quadra therapeutics is a virtual nonprofit (501(c)(3)) pharmaceutical company. To support a Prior Approval Supplement for a change in formulation, we had to undertake three bioequivalence studies for a multisource products as there are several NDA's approved with different therapeutic equivalence AB codes. For two of the studies, we met the bioequivalence criteria for AUC and Cmax. For the third study, we met the bioequivalence criteria for AUC. However, for Cmax, the scaled ABE for was LCmax 95% Upper bound 0.0024. There do not appear to be any specific FDA guidance expressly stating the number of significant figures required in the nonzero calculations for RSABE. In the FDA Draft Guidance, Bioavailability and Bioequivalence Studies for Orally Administered Drug Products – General Considerations (July 2002), I did find the following language. "If the study estimate of standard deviation is 0Tσ≤, the constantscaled criterion and its associated confidence interval should be computed. Otherwise, the referencescaled criterion and its confidence interval should be computed. If the upper confidence bound for the appropriate criterion is negative or zero, conclude population BE. If the upper bound is positive, do not conclude population BE." This is uncharted territory for us. is there any precedence for this? Should we truncate our results to 0.00? Can we conclude BE in our study report? If we can conclude BE, should we truncate the Cmax value to 0.00? Any help would be appreciated. Edit: Please don’t shout! [Helmut] — Biostatistically Challenged CEO 
Helmut ★★★ Vienna, Austria, 20201023 01:56 (1364 d 01:50 ago) @ Sereng Posting: # 22048 Views: 3,073 

Hi Sereng, ❝ […] For two of the studies, we met the bioequivalence criteria for AUC and Cmax. For the third study, we met the bioequivalence criteria for AUC. However, for Cmax, the scaled ABE for was LCmax 95% Upper bound 0.0024. Bad luck. If studies are powered to 80% and all assumptions are exactly realized, one out of five is expected to fail by pure chance (i.e., the type II error hits). Business as usual. ❝ There do not appear to be any specific FDA guidance expressly stating the number of significant figures required in the nonzero calculations for RSABE. Correct. ❝ In the FDA Draft Guidance, Bioavailability and Bioequivalence Studies for Orally Administered Drug Products – General Considerations (July 2002),… Where did you find this goody? Even Revision 1 of March 2003 was removed from the FDA’s site and can be found only in the Internet Archive. Both Population and Individual BE were removed in Rev. 1 and only ABE kept. ❝ … I did find the following language. "If the study estimate of standard deviation is ≤σ_{T0}, the constantscaled criterion and its associated confidence interval should be computed. Otherwise, the referencescaled criterion and its confidence interval should be computed. If the upper confidence bound for the appropriate criterion is negative or zero, conclude population BE. If the upper bound is positive, do not conclude population BE." OK, the same text is given in the “Statistical Approaches Establishing BE” of Jan 2001, which seemingly still is in force. However, according to what you wrote above, you are dealing with RSABE, not PBE/IBE.
❝ This is uncharted territory for us. is there any precedence for this? Duno. ❝ Should we truncate our results to 0.00? Because you don’t like it? 0.0024 is positive. Hence, \(\small{H_0}\) of inequivalence in \(\small{(1)}\) is not rejected. There is not a single word about rounding of the upper bound in any guidance. Where would you draw the line? Would you round 0.4999 (commercial) or 0.5 (ISO/IEC/IEEE 60559:2011) down to zero as well? ❝ Can we conclude BE in our study report? You can try anything. Technically and acc. to the guidance you failed to demonstrate RSABE. ❝ If we can conclude BE, should we truncate the Cmax value to 0.00? What do you mean by that? — Diftor heh smusma 🖖🏼 Довге життя Україна! _{} Helmut Schütz The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes 
jag009 ★★★ NJ, 20201023 09:06 (1363 d 18:41 ago) @ Helmut Posting: # 22049 Views: 2,940 

❝ ❝ Should we truncate our results to 0.00? ❝ ❝ Because you don’t like it? 0.0024 is positive. 