Particle Morphology as a Critical Material Attribute in Pharmaceutical Development: Characterization, Quality Impact, and Control Strategies

Particle morphology plays a key role in the physical, chemical, and processing properties of active pharmaceutical ingredients (APIs) and excipients. This review examines how particle size, shape, surface texture, and crystallinity influence pharmaceutical development and manufacturing. It outlines the main characterization methods, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), laser diffraction, dynamic light scattering (DLS), and Raman chemical imaging. The review also covers how particle morphology influences drug properties like dissolution rate, bioavailability, powder flow, compressibility, content uniformity, and aerodynamic behavior. Both top-down methods, such as milling and homogenization, and bottom-up methods, such as crystallization and spray drying, are discussed within the Quality by Design (QbD) framework. Regulatory guidelines from the International Council for Harmonization (ICH) and pharmacopeial standards are included. The article examines the role of particle shape in drug delivery for oral, pulmonary, and parenteral routes. Although there have been many advances, challenges remain in achieving reliable three-dimensional characterization, scaling up engineering methods, and creating standardized shape descriptors. This review aims to serve as a useful resource for scientists, formulators, and regulatory professionals seeking to leverage particle morphology to improve drug quality and performance. In summary, research shows that particle morphology is an important material attribute in pharmaceutical development. It needs careful, risk-based characterization, clear, science-based specifications, and integrated control strategies throughout the product’s lifecycle.