Bioequivalence and Bioavailability Forum

Dear Kotu!

❝ suppose i got cv 32.5 and t/r ratio is 97%. how to decided the sample size for further study.

Some remarks following D. Labes’ post. HVDs/HVDPs show also fluctuating PEs across studies. Quoting the two Lászlós:

Larger absolute differences between the two logarithmic means can be noted in the various BE studies when the within-subject variation is higher. Therefore, it is recommended that a 10% deviation between the means, i.e. a true GMR = 1.10, be considered when the sample size tables in the Appendix are used.

Since power curves are not symmetrical in raw scale I would recommend the more conservative 0.90 instead of 1.10 – which would give for CV 35% and 80% power:
    3-period  4-period
EMA    51       34
FDA    37       26
Since you expect a CV of 32.5% it might well be the case that in the actual study the reference does not classify as a HVD/HVDP – which would change the regulatory requirement to unscaled ABE!
  CV%  3-period  4-period
 30       60       40
 27.5     51       34