Bioequivalence and Bioavailability Forum

Dear Srinetram
Because of the complicated regulatory expectations, the features of the required sample sizes are also complicated. When the true GMR = 1.0 then, without additional constraints, the sample size is independent of the intrasubject variation. When the true GMR is increased or decreased from 1.0 then the required sample sizes rise at above but close to 30% variation. An additional regulatory constraint on the point estimate of GMR and a cap on the use of expanding limits further increase the required sample size at high variations. Fewer subjects are required by the FDA than by the EMA procedures. For further Information please refer to the article of the two Laszlos

L Tóthfalusi and L Endrenyi
Sample Sizes for Designing Bioequivalence Studies for Highly Variable Drugs
J Pharm Pharmaceut Sci 15(1), 73 – 84 (2011)
http://ejournals.library.ualberta.ca/index.php/JPPS/article/download/11612/9489

I hope this helps.
Kind regards
Dr_Dan