Levels of Solid State Properties: Role of Different Levels During Pharmaceutical Product Development

Oral and liquid solids are the most widely and popularly used therapeutic goods which provide ease of administration and cost-effective solutions for other dosage forms. Development of tablets and capsules (primary used orals solids) of existing drugs or a new chemical entity requires an in-depth understanding of their solid-state properties. Structural features (1°/2°/3°/4°), structural conformation, solid state (amorphous, solvates, hydrates, crystalline), solid-state stability (chemical and physical), and general characteristics such as particles size are some major solid-state properties. Many procedures or methodologies involved in pharmaceutical product development (salt formation, granulation, mixing, blending, homogenization, etc.) require a complete knowledge of solid-state properties. From a pharmaceutical perspective, the solid states of the bulk drug (polymorphs, enantiomer, hydrates, solvates, crystal) determine apparent solubility which in turn govern the systemic availability of that drug. This chapter also aims to discuss the concepts of polymorph types, formulation, and evaluation along with the different levels of solid-state properties, such as molecular level, particle level, and bulk level. We end the chapter providing a brief overview on the importance and significance of solid-state properties in pharmaceutical product development.