Drying Cycle

Developing A Drying Cycle Using LYOGUARD® Freeze-Drying Trays

GORE™ LYOGUARD® Freeze-Drying Trays are designed to be compatible with existing open tray lyophilization operations. While drying cycle development methods should be the same, there are two key differences between GORE™ LYOGUARD® Freeze-Drying Trays and open metal trays that could affect the drying cycle:

• Vapor flow resistance of the membrane
• Heat-transfer differences

Water vapor flow differences

Unlike standard trays that are open to the environment, GORE™ LYOGUARD® Freeze-Drying Trays are completely enclosed in order to contain product and protect it from contaminants. Vapor from the sublimation process escapes through a microporous GORE™ Membrane made of expanded polytetrafluoroethylene (ePTFE) membrane.

It provides very high vapor-flow rates and should have minimal impact on most drying processes. However, drying cycle impact varies depending on individual formulation characteristics and process parameters, especially product depth in the tray. At fill depths of greater than 10mm (approximately 1L of product) the membrane resistance is negligible, and drying cycles up to 25 percent shorter have been reported during drug company testing.

Heat-transfer differences

Open stainless steel trays have a bottom that typically warps over time, reducing shelf contact. GORE™ LYOGUARD® Freeze-Drying Trays have a thin, flexible film bottom that conforms closely to the dryer shelf and improves heat transfer. This design enables faster freezing and drying and a more uniform product than provided by open steel trays.

Combined effects of vapor flow and heat transfer

Regardless of whether the drying portion of the process cycle is the same or shortened, most users will find that their overall process is faster due to significant reductions in or elimination of post-drying cleaning and processing steps, combined with the increased handling efficiencies of processing with GORE™ LYOGUARD® Freeze-Drying Trays.

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