Fine particle characterization is most effective when accomplished through a methodical process. The first step of this process often involves determining what material needs characterization. In general, the following instances are most often cited:
- When a new chemical entity or active pharmaceutical ingredient is identified
- When the production of an existing substance is changed (e.g., new salt form established, recrystalization process changed, milling parameters altered, etc.)
- When there exists two lots or batches of virtually identical material that behave differently in some manner.
The process for characterizing these types of materials will vary between companies and probably be dependent on the availability of equipment and the expertise of the associated departments.