Lyophilization of Parenteral Pharmaceutical Products

There are many other parenteral forms but some products are lyophilized. Some of the parenteral products are unstable in solution form, therefore, those products are lyophilized. Lyophilization increases the shelf life of the pharmaceutical drugs.

Penicillins, cephalosporins, erythromycin, doxycycline, chloramphenicol and some other products are unstable in the solution form. These products are lyophilized when produced as parenterals. This process is also known as freeze-drying.

Lyophilization is the removal of water from frozen state to the gaseous state without going in the liquid state. In lyophilization of parenterals, the drug is dissolved in an appropriate solvent and converted to ice form at a very low temperature between −50 °C and −90 °C. 

Now it is dried by applying vacuum to remove the solvent. All the processing is done aseptically using the equipment called lyophilizer. Vials are filled with the solution of the drug and covered with the special bung for lyophilization. Vials are sealed aseptically after the completion of lyophilization.

Related: GMP for Sterile Pharmaceutical Manufacturing

The process of lyophilization is critical in respect to sterility. It is important to validate the lyophilization process for media fill. Problems are encountered frequently in the sterilization of lyophilizers. Generally, lyophilizers are sterilized by moist heat method with pressure. Sterilization validation of the lyophilizers should be done parallel as of an autoclave.

Lyophilized finished product must be tested for sterility and stability of the product. Sterile water for injection (WFI) should be used to reconstitute the sample to be analyzed for sterility because bacteriostatic water for injection can kill the contaminants present in the sample.