Bioanalytical approaches, bioavailability assessment, and bioequivalence study for waiver drugs: In vivo and in vitro perspective

Evidence of differences in bioavailability from different oral formulations of the same therapeutic agents had become obvious by the early 1960s. The consequent 40 years have produced the body of scientific belief, debate, and policy on the subject of bioequivalence. The motivating force behind many of these events has been the continued interest of the food and drug administration (FDA) to improve the manner in which these studies are conducted, the quality of the data generated from such studies, and the methods by which they are evaluated. Bioanalytical data used to support regulatory submission needs to be accurate and reproducible. In order to have confidence in the reliability of the data, it is important that the analytical method used to generate it is well characterized and fully validated. However, bioavailability assessment (BA) and bioequivalence (BE) studies are necessary in filing of the data towards the drug approval. This review article describes the methods for assessing bioavailability and bioequivalence; and bioanalytical approaches of pharmaceuticals in vivo and in vitro and also a waiver of BA/BE studies based on the biopharmaceutical classification (BCS) system.