Bioequivalence and Bioavailability Forum

Dear all,

Please see the below results
Dependent       Ratio[%Ref]  CI_90_Lower  CI_90_Upper  ICV(%)
Ln(AUCINF_obs)  95.80        92.57        99.15        11.58%
Ln(AUClast)     96.23        92.78        99.82        12.33%
Ln(Cmax)        90.20        86.02        94.58        16.04%

The 90% CI for Ln(Cmax) is not within the limits 90% to 111.11%. As per the EMEA guideline on Investigation of BE study for the BE criteria of NTI drugs.

The maximum Ratio[%Ref]= 90.20% and corresponding Intrasubject CV= 16.04% for Ln(Cmax).

If we take T/R ratio = 90.20% and Intrasubject CV= 16.04% then sample size will be greater than 20000 to get 90% confidence intervals of log transformed Cmax, AUC0-t and AUC0-inf for data within 90.00 - 111.11 % to achieve 80 % power at 5% level of significance.(Ref. of formula: Shein-Chung Chow,Jan Shao (sample size calculation in clinical reserch, page 31, 32 ). Instead of ln (1.25)=0.20, I have taken ln(1.11)=0.10.

Is it right way to choose sample size for the next study

If we take T/R ratio = 95% to 105% and Intrasubject CV= 16.04% then sample size will be 109.

Please suggest me.

---

Edit: Table coded, UTF-8 characters removed. [Helmut]