Sereng ☆ USA, 20220128 20:37 (423 d 19:45 ago) Posting: # 22757 Views: 1,148 

Folks, I really appreciate the guidance from this Forum. We need to conduct a 4Period, 2Sequence, 2Formulation BE study per FDA "product specific guidance" (PSG). The PSG also asks us to use the RSABE approach for properly adjusting the BE acceptance criteria based on "reference variability and comparing test and referenced product withinsubject variability". Can we safely assume that conducting such a replicate study would (at least) reduce our sample size by 50% over a 2Period, 2Sequence, 2Formulation BE study? If correct, and assuming no more dropouts (from the longer study), would there be any additional sample size efficiency arising from the use of the RSABE? Any help would be much appreciated! Many thanks! 
Helmut ★★★ Vienna, Austria, 20220128 22:06 (423 d 18:17 ago) @ Sereng Posting: # 22758 Views: 890 

Hi Sereng, ❝ […] The PSG also asks us to use the RSABE approach for properly adjusting the BE acceptance criteria based on "reference variability… So far so good. ❝ … and comparing test and referenced product withinsubject variability". That’s rather unusual. Can you post a link to the guidance? ❝ Can we safely assume that conducting such a replicate study would (at least) reduce our sample size by 50% over a 2Period, 2Sequence, 2Formulation BE study? No, that’s wrong. See there. ❝ […] would there be any additional sample size efficiency arising from the use of the RSABE? The idea behind RSABE is to maintain power independent from the CV. — 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 
Sereng ☆ USA, 20220128 22:40 (423 d 17:43 ago) @ Helmut Posting: # 22759 Views: 946 

❝ Can you post a link to the guidance? Hi Helmut, many thanks for your response. Below are the PSG links, one PSG asks you to refer to the second, although the first one may have the information (Sorry, I don't know how to attach the document here). I look forward to your guidance. Regards https://www.accessdata.fda.gov/drugsatfda_docs/psg/Levothyroxine_Sodium%20capsules_NDA%20021924_RC%20Oct%202018.pdf https://www.accessdata.fda.gov/drugsatfda_docs/psg/Warfarin_Sodium_tab_09218_RC1212.pdf Edit: Full quote removed. Please delete everything from the text of the original poster which is not necessary in understanding your answer; see also this post #5! [Helmut] 
Helmut ★★★ Vienna, Austria, 20220129 13:19 (423 d 03:04 ago) @ Sereng Posting: # 22760 Views: 841 

Hi Najib, ❝ […] one PSG asks you to refer to the second, … The Draft Guidance on Warfarin Sodium of 2012 was the first describing the FDA’s method of referencescaling for NTIDs. All later ones refer to the first and state For details about the Method for Statistical Analysis Using the ReferenceScaled Average Bioequivalence Approach for narrow therapeutic index drugs, refer to the Guidance on Warfarin Sodium Tablets. For the sample size estimation see there (including examples and references). — 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 