On January 16, 2009, the FDA published a final rule requiring an abbreviated new drug application (ANDA) applicant to submit data from all bioequivalence (BE) studies the applicant conducts on a drug product formulation submitted for approval. In the past, ANDA applicants have submitted BE studies demonstrating that a generic product meets bioequivalence criteria in order for FDA to approve the ANDA, but have not typically submitted additional BE studies conducted on the same drug product formulation, such as studies that do not show that the product meets these criteria. The FDA now believes that additional BE study data may be important in determining whether the proposed formulation is bioequivalent to the reference listed drug, and will increase FDA’s understanding of how changes in components, composition, and methods of manufacture may affect product formulation performance. The rule is effective July 15, 2009.