Lyophilization stages

Germination Stage A lyophilized culture of M. purpurea is added to a 300 ml shake flask... 

Tank fermentation of Micromonospora inyoensis — Germination stage 1 Under aseptic conditions, add a lyophilized culture (or cells obtained from a slant culture) of M. inyoensis to a 300 ml shake flask containing 100 ml of the following sterile medium ... 

Ion binding by reduction of repulsive forces also causes the attractive forces between polyions to increase, and the cement paste thickens. This interaction between polyions may be regarded as a kind of bridge formed by multivalent ions located between the polyions. At this stage the cement paste has the characteristic of a lyophilic sol - high viscosity. 

The final purification steps are responsible for the removal of the last traces of impurities. The volume reduction in the earlier stages of the separation train is necessary to ensure that these high-resolution operations are not overloaded. Generally, chromatography is used in these final stages. Electrophoresis can also be used, but since it is rarely found in process-scale operations, it is not addressed here. The fin product preparation may require removal of solvent and drying, or lyophilization of the product. 

Inclusion of a cryoprotectant in the formulation can stabilize the protein during the freezing and drying stages of lyophilization.17 Excipients frequently... 

As shown in Figure 6.4, the water-insoluble monomer (M) is attracted to the lyophilic ends in the micelles, causing the micelles to swell. The number of swollen micelles per milliliter of water is on the order of 10. However, at the initial stages of polymerization (phase I) most of the monomer is present as globules that resemble those observed in suspension polymerization. 

All enzymes to be used in organic media have at a previous stage been in an aqueous phase. They are then transferred to the organic medium, and this transfer process involves removal of water. This can be achieved by lyophilization or just drying of the enzyme solution, possibly in the presence of a support material or other additives. Another possibility is to dilute the aqueous enzyme solution with a water-miscible organic solvent which dissolves the water and causes the enzyme to precipitate. In one version, the enzyme solution also contains a crystal-forming solute such as an inorganic salt or an amino acid [20]. In this case, crystals are formed and the enzyme covers the crystals. 

Lyoprotectants can affect enzyme stability in both stages of lyophilization the freezing and the drying stages. In the freezing stage of lyophilization, ice crystals form and have been shown to be a cause of enzyme denaturation. Studies have shown that when added as a lyoprotectant, the amorphous polyol mannitol stabi-... 

The need for two stages in the lyophilization process is that the free water, frozen to crystals, is readily removed under low pressure by sublimation. However, water bound by hydrogen-bonding to the crystalline lattice or molecular matrix of the product, especially if it is proteinaceous, is more difficult to remove and requires a much longer time and increased heat exposure. 

Final product isolation in a form suitable for further processing into the final dose form of the pharmaceutical, e.g., as a tablet or an injectable solution. Secondary production of this type is sometimes done in a separate facility, with the raw material referred to as the bulk product or, more recently, the active pharmaceutical ingredient. Examples of unit operations at this stage of processing include lyophilization, precipitation, or crystallization followed by solid isolation using filtration and drying techniques. In some cases, the final product must be produced in a sterile form, which introduces additional complications when selecting suitable process equipment. 

In addition to the qualification of the lyophilization process itself, it is usual to collect liquid samples at various stages of the manufacturing. In this way, the losses in active material or its degradation can be monitored throughout the process. 

N. Daraoui, P. Dufour, H. Hammouri, A. Hottot 2007 On line constrained optimization of the primary drying stage of lyophilization, American Institute of Chemical Engineers (AIChE) Journal, submitted, ref. AIChE-07-I0884. 

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