Bioequivalence and Bioavailability Forum

Dear colleagues, I am struggling with understanding the sample size “benefits” of a replicate study design for NTID. Specifically, for levothyroxine (T4), FDA states that the RSABE approach is to properly adjust the BE criteria based on reference variability and comparing T and R product within-subject variability. The T4, the OGD PSG (cross-referenced to the Warfarin PSG) states that the study must be replicate (2x2x4) and BE established using Cmax and AUC if: (1) Upper 95% CI is ≤0 using RSABE; (2) The 90% CI is within 80-125% (ABE); and (3) The upper limit of the 90% equal-tails CI of the within subject SD of T to R is less than 2.5

What are the sample size “benefits” or “efficiencies” of undertaking this study as a replicate CO design (e.g., Test 50 x 2; Ref 50 x 2) versus a 2-way CO (Test 100 x 2; Ref 100 x 2). Any help would be much appreciated. Many thanks!