Bridging bioequivalence studies.

In some new regions, an innovative drug of the original region was not marketed. However, after the patent of the innovative drug is expired, a generic copy of the innovative drug from the original region was introduced and approved for marketing in the new region. Another generic copy manufactured by the local sponsor of the new region is seeking for approval in the new region. Despite unavailability of the innovative drug, the regulatory authority of the new region still wants to approve the local generic copy based on assessment of bioequivalence between the local generic drug and the innovative drug. Following the bridging concept suggested by the ICH E5 guidance, we propose a method to evaluate average bioequivalence between the generic copy of the new region and the innovative drug of the original region using the generic copy of the original region as the bridging reference formulation. Sample size required by the bioequivalence study in the new region is also provided. Numerical examples illustrate the proposed method.