ABSTRACT
Characterization of drug substances and excipients is a very important step at the preformulation phase of product development. Although testing will involve additional time and cost, failure to carry out the appropriate characterization tests can be even more costly to the manufacturers if the finished product does not meet specifications. Characterization of raw materials creates a body of information that is very useful for validating raw material suppliers and understanding processes in the development of products. Besides, changes in drug and excipient particle size, crystal form, and solubility may further impact the biopharmaceutical quality of the drug product. The lack of such information leaves the formulator with little leeway for remediation action when a problem arises during formulation development or process scale-up. The knowledge derived from the characterization of raw materials can also serve to enable better specifications for materials procurement. This book chapter critically evaluates the techniques, ranging from common to state-of-the-art, employed to analyze individual and bulk properties of particles (e.g., size, shape, surface area, roughness, density, solubility, crystal form, flow, sticking and microstructure). For greater insight, drug substance-excipient physical (e.g., segregation and compaction) and chemical (e.g., compatibility) interactions are also discussed.
