Next-Generation Dry Powder Inhalers: Advances in Characterization and Evolving Regulatory Frameworks

Dry powder inhalers (DPIs) have emerged as a vital platform for pulmonary drug delivery, offering targeted deposition, improved patient compliance, and enhanced formulation stability. As DPI technologies continue to advance, comprehensive characterization and regulatory alignment are essential to ensure therapeutic efficacy and patient safety. In this review covered an in-depth overview of in vitro performance testing of DPIs, including delivered dose uniformity, aerodynamic particle size distribution, fine particle dose, fine particle fraction, emitted dose, and inhaler resistance. Also covered recent advances in analytical methodologies, emphasizing their significance in predicting ex vivo and in vivo performance and maintaining batch-to-batch consistency. Discussed the regulatory framework through the perspective of the FDA’s draft guidance on metered dose inhaler and dry powder inhaler drug products, particularly focusing on requirements for chemistry, manufacturing, and controls documentation, as well as bioequivalence assessment through in vitro and in vivo approaches. This review presents a comprehensive list of commercially available DPI products, along with product-specific guidance that outlines relevant FDA requirements. Furthermore, the review addresses critical aspects of stability testing and human factors engineering, underlining their roles in product lifecycle management and patient-centered design. This article combines scientific and regulatory viewpoints, and describes the evolution of DPIs in compliance with global quality and safety criteria.