Drying in Pharmaceutical and Biotechnological Industries

The process used for drying pharmaceuticals has a high impact on the final product characteristics, both on the active ingredient (high chemical purity product) and the end drug product (complex galenic formulation). For example, it is well-known that there is a direct relation between the absorption of the active ingredient and its characteristic crystalline or polymorphic form. In some cases, the latter is related to the procedure and conditions of drying. The consequences of the process used to dry a pharmaceutical product may be different depending on the development phase: pre-clinical studies or manufacture (production). The drying process may greatly influence the quality of the drug substances in several aspects: the polymorphic form of the active ingredient, the structural changes that may have an effect on the activity of the substance, the degradation products formed due to the drying conditions and the presence of residual solvents undesirable or above the permitted limits after drying. Consequently, it is important to know the influence of all the factors and to establish the product specifications, as well as the nature and limits of residual solvents, in agreement with current regulations. (A)