Lyophilisation is crucial in the creation of pharmaceutical ingredients with an extended shelf life, however, current methods can still be costly and time consuming. Hosokawa Micron reveals its new method of contained active freeze drying as a potential solution.
Hosokawa Micron
In the pharmaceutical industry the necessity of freeze drying (lyophilisation) is well known. Through removal of water, a product’s shelf life can be extended, with the added benefit of making storage and shipping easier. Additionally, in the case of active pharmaceutical ingredients (APIs), lyophilisation can ensure chemical stability at room temperature. In these instances, freeze drying is performed using trays.1,2
However, as a process this can be costly, complex and labour-intensive, which has led to a drive in the industry to adapt methods to streamline lyophilisation. In light of this, Hokosawa Micron has developed a method using a single sterilisable, closed vessel to deliver lump free, fine powder product.
A closed process
In active freeze drying, the initial step is freezing of the product, which is done within a specially designed chamber. The material to be dried can be a liquid, solid or paste as a result of the agitation freezing process employed by the chamber.
Once frozen, sublimation begins, which is applied through the vessel jacket and distributed throughout the product by the stirrer. The frozen material sublimes, creating a loose powder that is then transferred to the collection filter.
Figure 1: Active freeze drying
Figure 1
“Every production step is completed within a single, sterile closed chamber,” explained Gerard Geurtsen, senior application engineer at Hosokawa Micron. “There is no dust to compromise operator safety. Nothing can enter the sealed system to contaminate the product within. Wet product is transferred from a reactor vessel, so no contamination risks associated with manual handling are introduced and aseptic operation enabled. When the vacuum is broken, on cycle completion, the finished dry powder is discharged directly into a container that was sterilised along with the full system internals before product entered the system (see figure 1). There is no requirement for additional containment equipment to protect operators or product for this pack-off stage.”
Lump free:
In tray drying procedures, the final product may require further crushing once collected. However, Hosokawa Micron state that using active freeze drying, this issue is removed and the resultant powder is often fine and uniform (see figure 2). “The product is very often porous and the easy dissolution facilitates for use in injections,” Guertsen said. “Without the need to introduce a milling stage the product is not damaged — we achieve ‘drying without harming’ of even the most sensitive, delicately structured products and living organisms.”
Figure 2
Figure 2
Aseptic processing:
As the system is fully contained it is suitable for aseptic processing. Cleaning of the system is performed by spray nozzles in the drying chamber, which commence on batch completion. Steam in place (SIP) is achieved using pressurised steam or hydrogen peroxide.
Cost:
“The Active Freeze Drying process is often faster and always less labour intensive than the traditional tray freeze drying process; producing lump free, free flowing powders in one step,” claimed Guertsen. “Consequently, handling times are shorter and simpler thereby saving time and money.”
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