Innovative approaches for demonstration of bioequivalence: the US FDA perspective.

In this article, the authors will briefly introduce the general concepts and background of bioavailability and bioequivalence (BE), discuss the conventional method for BE demonstration, and present case examples where novel approaches have been adopted by the US FDA for BE demonstration. Here, 'novel approaches' include unconventional BE studies, as well as statistical criteria for comparison. More specifically, biowaivers, methods to demonstrate BE for highly variable drugs and drug products, and narrow therapeutic index drugs, partial AUCs as additional metrics for some modified-release drug products, methods to demonstrate BE for locally acting gastrointestinal, dermatological, nasal and inhalation products, and non-biological complex drug products, and future perspectives in the field of BE assessment will be discussed. Methods adopted by other agencies, such as European Medicines Agency and Health Canada will be compared with the FDA approaches when appropriate.