Some implications of structural collapse during freeze-drying using Erwinia caratovora L-asparaginase as a model

When the enzyme Erwinia caratovora L-asparaginase was freeze-dried in mixtures of lactose and sodium chloride, biological activity and protein structure were preserved during drying. However, by altering the ratios of the excipients in the formulation it was possible to obtain products which were pharmaceutically acceptable or unacceptable as assessed by the criteria of dried cake appearance, moisture content or ease of reconstitution.