Many temperature-sensitive products involved in the biopharmaceutical industry (e.g., enzymes, vaccines, and monoclonal antibodies) exhibit a limited stability if kept in aqueous solution for a long time. A process that can be used to promote long-term stability for these products while avoiding the thermal degradation of their structure is freeze-drying (also known as lyophilization). It is the most substantial drying technique utilized in the pharmaceutical and biopharmaceutical industries.

Freeze-drying is suitable for thermolabile materials and able to produce dry products with high-quality attributes. But it is a time-consuming and energy-demanding process. It requires optimization of both process and formulation variables. The quality by design (QbD), and critical quality of attributes (CQAs) are important in freeze-drying. The formulation excipients and the dispersion medium play crucial roles in designing a successful process. Optimizing the freeze-drying cycle requires controlling the process parameters. Numerous approaches have been developed to ameliorate the freeze-drying performance.