ABSTRACT
Lyophilization is a process that is growing in its application as a method of production for preserving a wide variety of healthcare products—vaccines, therapeutic agents, and novel products developed from advances in biotechnology. Although principally considered a drying process, lyophilization consists of multiple processes. Although distinctly different, each part of the process has a common influence on finished product qualities, along with subsequent steps in the process. The sublimation of the ice must be completed in such a fashion that the integrity of the product characteristics formed during freezing are maintained during the entire process. Pharmacologically active compounds that are both heat sensitive and undergo chemical degradation by hydrolysis are those that benefit from low temperature drying where reaction rates are slow and any chemically active water may be removed. Freeze-drying a material with retention of initial characteristics requires that the process be completed while maintaining both the frozen and dried product below a critical phase transition temperature.
