FDA drug classification system.

The purpose and use of the FDA's classification system for new drug products are described. Investigational new drug applications (INDs) and new drug applications (NDAs) are submitted to the FDA's Center for Drug Evaluation and Research. To establish the priority of the product in the review process, expert reviewers classify each product according to chemical type and therapeutic potential. Drug products that receive a high therapeutic rating (e.g., 1AA or 1A) are reviewed for approval more quickly than drugs that receive a lower therapeutic rating (e.g., 1B or 1C). Because this system is the only national therapeutic rating system for drug products, it has been used in legislation, in clinical evaluation of new drug products as they are approved, and in formulary decisions. However, caution is needed because the therapeutic rating assigned at the time of the product's approval may not reflect its importance relative to all agents available at a later date. The FDA classification system was designed to guide new drug products through the application process and should be used only with caution for other purposes.