## FDA: 2×2×4 design; RSABE + ABE + σwT/σwR [Design Issues]

❝ All of the product-specific guidances contain a section ‘Explanation’. See also Yu et al.

OK

❝ ❝ Further, can we perform crossover studies for NTI by taking extra safety measurement in to the study?

❝ You can. Whether that is necessary in healthy volunteers depends on the drug.

Yes.

❝ ❝ Further, what is the BE limit for such drugs?

❝ It depends on $$\small{s_{wR}}$$ observed in the study, i.e., reference-scaling is applied. Furthermore – irrespective of passing the scaled limits – the study has to pass 80.00–125.00% as well and the upper confidence limit of $$\small{\sigma_{wT}/\sigma_{wR}}$$ has to be ≤2.5.

its common for all NTI or its varies from drug to drug?

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]

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