Bioequivalence and Bioavailability Forum

❝ ❝ What do you think about such an approach?

❝

❝ Personally I’m not happy with it – see also ElMaestro’s comments.

First of all: Thank you ElMaestro and HS.

I understand your thought about such an approach.

But let me argue in an other way:

I can do 'nearly' exacty the same divided in a pilot and a pivotal study.

First I perform the pilot study with 12 subject. After that i use the internal criteria:

calculated sample size for stage 2 is more than 60 subjects (due to ethical reasons) → reformulation of test product, otherwise perform pivotal study with the calculated sample size.

Only two difference are between this approach and the 2-Stage-Design approach

• the 2 stage Design approach save time (is faster) and effort/costs (1 study vs. 2 studies)
  
• in 2 stage Design approach i need 12 subject less, because i can use the 12 subjects of 1 (ethical argument)

Because I never reach BE in stage 1 (CV to high, CI will be wider than the acceptance range) I shouldn't have an alpha-inflation.
Stage 1 is only performed to get CV's for the power and sample size estimation of stage 2 – this is one of the fundamental ideas of a two-stage design.

Best regards
BEman