Bioequivalence and Bioavailability Forum

Hi,

❝ Potvin method is acceptable or not for FDA,

❝

❝ If yes how,

❝ if no why

Regulators tend not to give informative reasons.
But the answer to your question is yes, Potvin is acceptable. Do a controlled corr. with FDA to make sure you get everything right.
In particular, you may get a high CV by chance (risk increases if initial sample size is low, like n1=12) and this high CV may cause your sample size for stage 2 to become big, like 400 subjects. If you decide to cap sample size (like we will only go ahead with stage if n2 <80 or whatever), then the method has new properties in terms of power and type I error and you are expected to be able to present data for that if the agency asks. In general, your power drops a lot if you use such caps. You need to be absolutely aware of it, otherwise you'll be initiating a study that may have a very low chance of success even if power for stage 2 is set at 80% or higher.