FDA Warning Letters: A Retrospective Analysis of Letters Issued to Pharmaceutical Companies from 2010–2020

PURPOSE: To launch a pharmaceutical product in the US market, approval from the FDA is required. Pharmaceutical companies undergo FDA pre-approval inspection (PAI for small molecule products) or pre-license approval (PLI for biological products) at their manufacturing sites (including contract development and manufacturing organization, testing laboratories, and packaging labelling facilities) prior to approval. After the products are approved by the FDA, surveillance inspections are performed by the FDA which are risk based as which company and which site will be inspected. The present study examines the causes of warning letters issued by the Center for Drug Evaluation and Research (CDER), FDA to the pharmaceutical companies after post-approval inspections. METHODS: Warning letters issued from the time period 2010 to 2020 were obtained from the FDA website, and information about date of issuance, company, and type of violations was extracted for the study. RESULTS: Poor compliance to CGMP and misbranding were the most common reasons for the warning letters. Detailed analysis of CGMP warning letters elucidated three major types of violations, namely deficiencies in process validation, documentation practices (data integrity), and quality control corresponding to 26%, 21%, and 15% warning letters, respectively. CONCLUSION: Review of the analysed letters demonstrates that the FDA’s major concern is over CGMP compliance. To avoid these warning letters, pharmaceutical manufacturers need to improve their quality compliance and focus on creating effective quality management systems that govern the entire manufacturing process, quality control, employee training, and documentation practice. Companies should develop an internal compliance check list and also be ready for corrective measures as and when required. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12247-022-09678-2.