Bioequivalence and Bioavailability Forum

Dear Tina,

In addition to ElMaestro's response:

❝ (95 to 105) vs (90 to 110)—Which assumption (for calculating sample size) is preferred by the regulators

What the regulators are interested in is the result of the 90 % CI you will calculate at the end. They may take a look at your sample size calculation assumptions in order to check the study is not over­powered and you didn't "force" bioequivalence, but that's probably as far as they will go. The choice is fully yours.

❝ If regulators are fine with both, can we not take the option of (95 to 105) as it helps with lesser costs due to lesser sample size

Sure. But if you calculate your sample size based on 95-105, and the study fails because you get a point estimate of 92 in your study, you won't have saved any money. You have to find the right balance between risks, ethical considerations, and costs.