For entry into the world's largest market, the United States, compliance with the Current Good Manufacturing Practice (CGMP) standards of the U.S. Food and Drug Administration (FDA) is essential. Since COVID-19, the number of FDA Warning Letters issue...
For entry into the world's largest market, the United States, compliance with the Current Good Manufacturing Practice (CGMP) standards of the U.S. Food and Drug Administration (FDA) is essential. Since COVID-19, the number of FDA Warning Letters issued has consistently risen, suggesting an increasing quality risk among global pharmaceutical and biopharmaceutical manufacturers. The quality issue in the Active Pharmaceutical Ingredient (API) manufacturing process is particularly seen as the fundamental cause of overall product quality problems. Therefore, by limiting the scope to the API stage, where quality problems originate, and analyzing GMP violations, this research aims to present the perspective that regulatory agencies have recently deemed important for API manufacturers, along with practical solutions for improvement.
This study analyzed a total of 45 Warning Letters issued by the FDA between 2020 and 2025 where the Subject was classified as API. Analysis by year revealed that the overall number of Warning Letters is gradually increasing, with API-related letters accounting for approximately 10% of the total. The citations were classified into major and minor categories based on the ICH Q7 Guideline. In the major category classification, Documentation and Record constituted the largest share at 24.29% of all citations, followed by Quality Management and Laboratory Controls. In the minor category classification, Responsibilities of the Quality Units exceeded 10% of the total, with Documentation System and Specification, Laboratory Control Records, and Equipment Maintenance and Cleaning being the next most frequently cited. Overall, the top three minor categories accounted for approximately 30% of all citations.
Among the 45 Warning Letters, 17 were for India, 12 for the United States, 8 for China, and 8 for other countries. While there were no major country-specific peculiarities, nearly all manufacturers in China and the U.S. (all but one in each) were cited for Responsibilities of the Quality Units. This confirmed that issues with the responsibility of the quality department are a major citation leading to inspection failure, particularly in China and the U.S.
Subsequently, a detailed content analysis was performed on the three most frequently cited minor categories. Based on this, a checklist was proposed for domestic and international API manufacturing companies to inspect and establish CGMP-level quality systems. The proposed pre-inspection checklist will serve as a stepping stone for future entry into the U.S. market and will contribute to raising the quality level of each manufacturing facility.