Back to: Navigating Controlled Correspondences to Support Generic Drug Development
Presenter
Qiangnan Zhang, PhD
Staff Fellow
Division of Therapeutic Performance I (DTP I)
Office of Research and Standards (ORS)
Office of Generic Drugs (OGD)
Center for Drug Evaluation and Research (CDER)
US Food and Drug Administration (FDA)
Abstract
This presentation covers key considerations and best practices for preparing for a Q1/Q2 Sameness Inquiry. Q1 sameness means using the same inactive ingredients as a reference listed drug (RLD), while Q2 sameness requires the concentrations of these inactive ingredients to be within 5% of the RLD’s. Q1/Q2 sameness is required by regulation for drug products intended for parenteral, ophthalmic, or otic use, with limited permissible differences. It may also be recommended by Product-Specific Guidance (PSG). Preparing a Q1/Q2 controlled correspondence involves submitting a detailed composition table using official names and specifying ingredient grade, focusing on a nominal-based comparison. While typically not required, comparative characterization data may be needed for Q1 sameness assessment in specific cases, such as for certain polymers. The presentation also discusses submitting a controlled correspondence to justify differences in pH adjusters for waiver requests in certain product types. The FDA’s response to a Q1/Q2 assessment indicates whether an ANDA based on the proposed formulation would likely be refused or potentially eligible for certain bioequivalence waivers or recommended studies. Useful resources including regulations and guidance documents are also highlighted.