Bioequivalence and Bioavailability Forum

Hi all,

In my opinion, sample size calculation is 90% gut feeling and 10% math

Sample size for BABE studies is always hard since there is no much information in the literature and the variability of the test product is always unknown. Most of the time, the information we have is from drug interaction or food interaction studies, which in principle will provide us with higher CVs then expected for BABE trials. Other times, you find one or two sources about the CV and rarely the results are completely opposite (ie one reporting a CV of 28% and another a CV of 5%). At least, this is my experience unless I'm not doing my research correctly

I usually go with mittyri conservative approach because negative studies due to lack of power are a guarantee of client insatisfaction And the costs of a few additional subjects compared with the cost of failure are considerably low and it is always better to play safe, imo.

For therapeutic studies I usually provide more "sophisticated" calculations and sensitivity analysis. Most of the time, the calculations are "Money client have/Cost per patient". But the variability and cost per patient are so much higher than in BABE studies that sometimes adding more 10 ou 20 patients may be out of the budget.