For filing abbreviated new drug application (ANDA), an applicant generally must demonstrate that their drug candidate is reasonably bioequivalent to the reference listed drug (RLD). To this end, FDA regulations require an applicant to use the most accurate, sensitive, and reproducible approach available among those outlined in the FDA guidance on bioequivalence (21CFR 320.24(b), Procedures for Determining Bioavailability and Bioequivalence). As per these guidelines, the descending order of determining bioequivalence (BE) includes pharmacokinetic, pharmacodynamic, clinical, and then in vitro studies. Here, the establishment of BE based on pharmacokinetics relies on endpoints such as Cmax and AUC for a direct comparison between the two products. Applicants may conduct a pilot study before full BE study to validate the analytical methodology, optimize sample collection time intervals, and flesh out protocol details.