Freeze-drying product design

Another concept is the automatic loading and unloading system for freeze-drying chambers that have been designed as push-through chambers. In such cases, the sterile loading side (unprocessed product) is separated from the sterile unloading side (freeze-dried product). 

The range of rubber materials includes natural and synthetic-based materials. Special designs of rubber (e.g. castellated) are available for lyophilised/freeze dried products. Surfaces may be coated, e.g. with PTFE or Parylene, to reduce any extractability risks. 

Figure 14.7 Production freeze-drying system designed for instaiiation over two floors.

Fig. 2.28. Schema of a vacuum pump set, designed for a production freeze drying plant.

The book describes the up-to-date fundamentals of freezedrying, not just presenting the process in all its seven steps theoretically, but explaining it with many practical examples. Many years of experience in freeze-drying allow the authors to supply valuable criteria for the selection of laboratory, pilot and production plants, discussing the advantages, drawbacks and limitations of different plant designs. 

The functional relationship between product temperature, on the one hand, and shelf temperature and chamber pressure, on the other hand, is affected by many factors including the size and design of the lyophilizer, the characteristics of the product, and the time evolved since the start of primary drying. With a sucrose formulation in vials, we have observed a maximum primary drying product temperature rise of -i-5°C when the shelf temperature was varied from -15 to -i-30°C, whereas a pressure variation from 30 to 250 microbars generated an increase of around -i-2.5°C. With a lactose formulation in ampoules lyophilized in a larger freeze-dryer equipped with a plate-type condenser, the effect of pressure was found to be predominant -i-6.5°C for a pressure move from 50 to 300 microbars, versus -t-l°C for a shelf temperature move from 0° to 25°C. 

The purpose of Freeze-Drying/Lyophilization of Pharmaceutical and Biological Products is not to present an exhaustive view of the process, but essentially to shed light on some focal areas of the field in which pioneering research has been achieved and assess its impact on current manufacturing practices. This book also provides a critical review of such wide issues as the design and construction of equipment to identify the main trends and sometimes locate the specific sectors where our technological know-how is still incomplete. 

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