Mesalazine, also known as 5-aminosalicylic acid, is a medication used to treat inflammatory bowel disease. Mesalazine impurities are unwanted substances that can be present in the drug, which may affect its safety and efficacy. These impurities can be caused by various factors such as manufacturing processes, storage conditions, and degradation. Therefore, it is important to identify and control these impurities to ensure the quality and consistency of mesalazine products.