PRINCIPLE. The main principle involved in freeze drying is a On 21st century, in pharmaceutical field lyophilization has become important. Lyophilization, or freeze drying, is a process in which the solvent (usually water) is: first frozen and then. – removed by sublimation in a vacuum. Freeze drying, also known as lyophilisation or cryodesiccation, is a low temperature . Bulk lyophilization of APIs is typically conducted using trays instead of glass vials. .. Food processing technology: principles and practice ( 4th ed.).

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The form of the container. Sublimation, and the qualities of the finished product are greatly dependent principke this crystal structure. System pressures in the mTorr to mTorr range will usually promote an adequate amount of convection. This regulation requires certain standards of process control and security. A laboratory example illustrates the influence of pressure in heat transfer:.

Product is either pre-loaded into vials which are then transferred to the shelf or it is loaded in bulk form directly onto a product tray. This simple control will greatly improve the energy transfer and reduce primary drying times.

General Principles of Freeze Drying

A new form of burial luophilizer previously freeze-dries the body with liquid nitrogen has been developed by the Swedish company Promessa Organic ABwhich puts it forward as an environmentally friendly alternative to traditional casket and cremation burials. In these cases, freeze-drying may not be an effective restoration method. These crystals seem to be contained in an interstitial state, still liquid, but which constitutes the principal active element of the solution.

Product chambers are typically either a manifold with attached flasks, or, a larger chamber with a system of shelves on which to place the product. Contrary to widely held opinion, it is not necessary to have a very low vacuum during the sublimation period, because below the limit defined, the evaporation rate is not improved, and that too low a pressure acts as a barrier to effective heat transfer.


The surface area inside the bottle being around 0. Equally important is that in liquid-phase drying there is an undesirable shrinkage and concentration of active constituents that causes damage as well as a movement of these constituents to the surface of evaporation, where they form a dense, impermeable skin that inhibits drying, and later, rehydration. Lower temperatures are required to freeze and condense solvents and they can easily bypass the condenser and end up causing damage to the vacuum pump.

Because of the lack of control over the rate of heat transfer into the product, most manifold dryers are operated conservatively at lower pressures to help keep the product temperature lower.

Secondary drying is continued until the product has acceptable moisture content for long term storage. The Pfinciple gauge, however, will give a false high reading in the presence of water vapor. Freeze Drying can only take place if the partial pressure of the vapor in the drying chamber is lower than the water vapor pressure above the product. One such method entails comparison of parallel pressure readings between a Pirani gauge and a capacitance manometer.

To facilitate faster and more efficient freeze drying, larger ice crystals are preferable. As the role of the vacuum pump is limited to eliminating the tiny traces of non-condensable gases, one could conclude that the real vacuum effect is derived from principke ice condenser via the pressure differential created by the surface temperature of the product and the condenser. Frozen products can be categorized as either crystalline or amorphous glass in structure.

Insure the necessary low temperature saturated suction during lyophilized secondary drying to deliver the lower vacuum levels needed for this phase. From Wikipedia, the free encyclopedia. The freezing phase is the most critical in prrinciple whole freeze-drying process, as the freezing method can impact the speed of reconstitution, duration of freeze-drying cycle, product stability, and appropriate crystallization.

The liquid shelf on which the product is placed.

Freeze-drying – Wikipedia

However, for industrial production settings, freezing at the same rates is unrealistic because of the problems of product preparation filling, loading time and larger systems costs will dictate compromises in the same process. Each specific product or formulation that is lyophilized requires the development of a freeze drying process that is based on the unique characteristics of the product, the amount of product and the container used. This phase is identified as secondary drying.


By removing the water from the material and sealing the material in a glass vialthe material can be easily stored, shipped, and later reconstituted to its original form for injection. During annealing, the product temperature is cycled for example: Freeze Drying is a complex operation, and all facets cannot be addressed in this type of explanation.

Shelf-life extension is a result from low processing temperatures in conjunction with rapid transition of water through sublimation. Typically, there are multiple steps involved for both freezing and drying of the product. Pharmaceutical companies often use freeze-drying lyophilkzer increase the shelf life princile the products, such as live virus vaccines, [13] biologics [14] and other injectables. Also, the flask might break due to uneven stress.

With manifold freeze drying, the process is driven by the system pressure set point and the ambient temperature in the room. Request a Quote Interested in learning more about our products? The vacuum system consists of a separate vacuum pump connected to an airtight condenser and attached product chamber. Active Pharmaceutical Product Ingredients APIs are lyophilized to achieve chemical stability under room temperature storage. Permit easy defrosting after the run.

However, there are products that benefit from increased pressure as well. Major equipments used in cell culture. Primary drying is a top-down process with a well-defined sublimation front moving through the product as it dries. The difference in particulates can greatly affect product freezing and ice crystal size.