Method for measuring shelf temperature uniformity (distribution verification) during lyophilizer operation in pharmaceuticals

When considering freeze-drying pharmaceutical applications, the primary concern is the ability to produce consistent products with desired critical quality attributes

Product temperature is the criterion for validating the freeze-drying process, but there are many benefits to knowing shelf temperature in conjunction with product temperature

Also, because of the thermal resistance caused by the high vacuum, most of the energy is transferred by radiation, which makes the use of traditional touch sensors problematic unless they are designed for this purpose

There is a need for an easy-to-handle isothermal block to eliminate home-made solutions

• Ultra-thin replaceable thermocouple sensor
• Real-time online temperature data display and storage
• Easy to repeat for consistent and accurate measurements
• Eliminates bulky and homemade alternatives
• Excellent performance in ambient conditions as well as in vacuum
• The isothermal block is made of PEEK material and 316L stainless steel

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Each shelf should have 5 measuring points, one in each corner and one in the middle

Measurements need to be made on all shelves in order to measure the actual situation and fully assess the safety margin of the entire load

Maximum variation between shelves: +/- 0.

Maximum variation within shelf: +/-2°C (or according to manufacturer's specification)

Measurements should be made on fully loaded and unloaded shelves, as both cases provide important information on how the shelf configuration performs under load and without load

· Shelf/product temperature should be measured with the highest possible accuracy

• When measuring, the chamber should be at ambient pressure during the temperature of the cooling phase and under vacuum during the temperature of the heating phase

For a pharmaceutical company lyophilizing product in vials:

• Freeze dryer with 10 shelves

• Collapse temperature is -15°C

• The maximum shelf temperature allowed during secondary drying is +35°C

• 50 loggers (10 x 5) measuring shelf temperature at +25°C (ambient), 0°C and -20°C in all 4 corners and all 10 shelf centers

Temperature, at atmospheric (ambient) pressure

• 50 loggers (10 x 5) measuring shelf temperatures at -20°C, 0°C, +20°C and +40°C in all 4 corners and all 10 shelf centers, in a vacuum environment Down

• The temperature change (gradient curve) will be calculated for each shelf (inside) and shelf (between) at each temperature (7 studies in total) and the data will be compared to manufacturer specifications to determine pass or fail qualified