Misunderstanding Design Space: a Robust Drug Product Control Strategy Is the Key to Quality Assurance

Abstract

ICH guidelines Q8/11, Q9, and Q10 introduced risk-based approaches and enhanced scientific understanding as an opportunity to encourage continuous process improvement for pharmaceutical manufacturing. Conceptually, Quality by Design (QbD) promised to improve confidence in quality through the lifecycle of pharmaceutical products. A primary incentive for industry is the prospect of global regulatory concordance for new applications and post approval changes. Unfortunately, during the last decade, the industry has experienced regulatory divergence regarding the interpretation of ICH guidelines across geographic regions. Rather than truly harmonized regulatory expectations, localized interpretations of ICH guidance have resulted in different technical requirements posing significant challenges for a global industry. As a result, the increased complexity of manufacturing supply chains and the regulatory burden associated with maintaining compliance with these diverse regulatory expectations serves as a barrier to continual improvement and innovation. The QbD paradigm has effectively demonstrated a risk-based link between a product’s control strategy and patient needs that has prompted meaningful improvement in the industry’s approach to product quality assurance. Divergent interpretations of the concepts and definitions used in the modern QbD approach to product development and manufacturing, however, has led to challenges in achieving a common implementation of design space, control strategy, prior knowledge, proven acceptable range, and normal operating range. While the concept of design space remains an appealing focal point for demonstrating process understanding, the authors suggest that Control Strategy is the most important QbD concept, and one that assures product quality for patients. A focus by both regulators and manufacturers on the significance of Control Strategy could facilitate management of post approval changes to improve manufacturing processes and enhance product quality while also engendering regulatory harmonization.