Bioequivalence and Bioavailability Forum

Hi gsrao,

❝ 1. If any molecule intra subject CV of Cmax is less than 30 and for AUC more than 30. in this case can we go for replicate design for EU regulatory?

A replicate design is always accepted.

❝ 2. For replicate study design which should be preferred partial replicate or full replicate?

From a statistical perspective, a full replicate is preferred. When you are concerned about dropouts or the bioanalytical method requires large sample volumes, opt for one the 2-sequence 3-period designs (TRT|RTR or TRR|RTT).

❝ … which is preferred by regulatory?

Any one is fine. If you opt for a 2-sequence 3-period design (TRT|RTR or TTR|RRT) you need at least 12 eligible subjects in the sequence where R is repeated (see the Q&A document). However, that’s not relevant in practice, unless you face an extreme dropout-rate (see this post).

❝ 3. What is the maximum half life to go for Parallel study?

No fixed rules.

❝ 4. What is the minimum days of wash out period required (in days) for eg. if a molecule half-life is 1 hour?

In days? With ¹/₅ you are on the safe side. 
Never plan based on an average t_½. The shortest washout I ever had were three days.

❝ 5. If a study passes 90 % CI, but the power is below 80 does regulatory approves the study?

Post hoc (a posteriori, retrospective) power is completely irrelevant (not only on BE) and there is no reason to reject a successful study. It is not mentioned in any of the current global guidelines. Therefore, stop calculating it and – for educational reasons – stop reporting it. See also what the WHO states. If any agency has [stupid] questions, hire me.