Factors Influencing Powder Compressibility: Mechanistic Insights for Robust Pharmaceutical Tablet Manufacturing

Compressibility is a critical material attribute in tablet manufacturing, as it governs powder densification, inter-particulate bonding, and the mechanical integrity of solid oral dosage forms. Intrinsic solid-state properties such as polymorphism, crystal structure, molecular packing, slip planes, and hardness influence the primary mechanism for deformation and ultimately determine whether materials undergo plastic deformation, elastic deformation, or brittle fracture during compaction. These effects are controlled by the properties of the particles and surface properties. Factors such as particle size and shape, surface free energy, particle aggregation, density, and flow affect the development of the contact area and the transmission of stress within the tablet. Environmental conditions and processing parameters also alter these fundamental responses, thereby affecting densification efficiency, tensile strength, and defect formation. Compressibility, compactibility, and tabletability are determined by these interrelated factors, which ultimately influence manufacturability and product robustness. This review emphasizes the importance of a holistic understanding of the mechanisms governing API compressibility by integrating solid-state properties, compaction behavior, and empirical modeling techniques. It highlights how these interconnected factors influence powder desnsification, mechanical strength, and tablet performance, providing a scientific framework for the rational design and optimization of pharmaceutical formulations. Furthermore, the concept discussed in this review may facilitate the application of Quality by Design(QbD) principles and support the development of robust manufacturing strategies for solid oral dosage forms.