File Entry: HOW TO START ANALYTICAL METHOD DEVELOPMENT

 A bulk drug during its production process, after its scale up, it is necessary to analyse for the presence of any impurities or related substances in it. This is to ensure the impurities and related substances are within their limits as per ICH Guidelines.The impurities and related substances are defined as; Impurity: Any component present in the drug substance or drug product which is not the desired product, a product-related substance, or excipient including buffer components. It may be either process-related or product-related¹. Related substances: Those impurities derived from the drug substance. Related substances include degradation products, synthetic impurities of drug substance, and manufacturing process impurities from the drug product².  ICH Guideline Q3 A gives the impurities present in a drug substance, ICH Guideline Q3B gives the impurities present in drug product. The Guideline addresses the chemistry and safety aspects of impurities, including the listing of impurities in specifications and defines the threshold for reporting, identification and qualification.