Setting a Fill Weight Target and Control Limits for Drug Product Presentations

For a given drug product presentation, the design of the fill weight strategy is a critical element to ensure that patients receive the correct dose. The fill weight strategy is comprised of fill weight target selection and the action limits around the target. Health regulatory agencies and pharmacopoeia are the primary sources of guidance on setting the fill weight strategy. The focus of this publication is to share practical approaches to the design of liquid and lyophilized drug product presentations, based on knowledge of regulatory guidance, drug product formulation properties, manufacturing capabilities, and knowledge of the primary container and in-use components. This is illustrated through four hypothetical case studies that are based on real-world experience. Considerations that need to be taken into account for liquid vs lyophilized, volume-based versus container-based dosing, and biosimilar presentations are discussed. The application and advantages of real-time release testing for deliverable volume of liquid drug products and total protein content of lyophilized drug products are also described. Furthermore, in order to more effectively discuss this topic across the industry and with health agencies, a standardized nomenclature for common terms related to fill weight strategy is proposed.