Follow
Lyophilization or freeze drying is a process in which water is removed from a product after it is frozenand placed under a vacuum, allowing the ice to change directly from solid to vapor without passingthrough a liquid phase. The process consists of three separate, unique, and interdependent processes;freezing, primary drying (sublimation), and secondary drying (desorption).
The advantages of Lyophilization include:
Ease of processing a liquid, which simplifies aseptic handling
Enhanced stability of a dry powder
Removal of water without excessive heating of the product
Enhanced product stability in a dry state
Rapid and easy dissolution of reconstituted product
Disadvantages of lyophilization include:
Increased handling and processing time
Need for sterile diluent upon reconstitution
Cost and complexity of equipment
The lyophilization process generally includes the following steps:
Dissolving the drug and excipients in a suitable solvent, generally water for injection (WFI).
Sterilizing the bulk solution by passing it through a 0.22 micron bacteria-retentive filter.
Filling into individual sterile containers and partially stoppering the containers under asepticconditions.
Transporting the partially stoppered containers to the lyophilizer and loading into the chamberunder aseptic conditions.
Freezing the solution by placing the partially stoppered containers on cooled shelves in a freeze-drying chamber or pre-freezing in another chamber.
Applying a vacuum to the chamber and heating the shelves in order to evaporate the water from thefrozen state.
Complete stoppering of the vials usually by hydraulic or screw rod stoppering mechanisms installedin the lyophilizer.
