Determination of sample size for two stage sequential designs in bioequivalence studies under 2x2 crossover design

Sequential design is an adaptive design that allows for pre-mature termination of a trial due to efficacy or futility based on the interim analyses. The concept of sequential statistical methods was originally motivated by the need to obtain clinical benefits under certain economic constraints. That is for a trial for a positive results, early stopping ensures that a new drug product can exploited sooner, while negative results indicated, early stopping avoids wastage of resources. In short, the right drug at the right time for the right patient. Furthermore, the possible implication of two stage sequential design/ sample size re-estimation is to adjust the sample size based on the observed variance estimated from the first stage. The purpose of this work was to determine the minimum number of sample size required to proceed the second stage of sequential design, and the simulation is done through R ve. 3.0.3 Statistical software package. In general, from our simulation study, we can understand that, for highly variable drugs (CV ≥30), the appropriate GMR value is between (0.95, 1.05), which is also appropriate for low variable drugs to achieve the minimum sample size required to conduct any clinical trials.