Bioequivalence and Bioavailability Forum

Dear Alpesh!

❝ For normal cases 80% or more power is required to calculate the sample

❝ size for BE studies.

>80% is not required, but desired. Since the producer’s risk (β) = 1–power, it depends on the budget of the sponsor.

❝ But, when it is mandatory to use more then 80 % (i.e., 90%) for

❝ calculation.

❝

❝ Mean to say what can be the special situations where we have to go for

❝ power 90% instead of 80 %.

You may want to aim for power >80% in order to adjust for the expected drop-out rate (AEs, more than two periods, etc.). ICH E9 (Statistical Principles for Clinical Trials, Section 3.5, 1998) calls for a sensitivity analysis in the planing stage. You should investigate violations of assumptions (larger deviation the T/R-ratio, higher CV, drop-out rate) on power (based on a given sample size). For details see one of my lectures.