Apparatus and method for developing freeze drying protocols using small batches of product
A method and apparatus for eliminating or minimizing the non-uniformity of edge vials compared to center vials during freezing or primary drying of product therein in a freeze dryer. A temperature controlled surface is positioned in close proximity to or in contact with the edge vials to control the temperature thereof. The method and apparatus may be used to simulate in a development freeze dryer the conditions of the center and edge vials in a larger batch target freeze dryer.
1. An apparatus for eliminating or minimizing non-uniformity of edge vials compared to center vials during freezing and/or primary drying of product therein in a freeze dryer, comprising:
a temperature controlled surface surrounding both the edge vials and the center vials, wherein the temperature controlled surface is positioned in direct contact with or direct connection to the edge vials, or connected to the edge vials via a thermal conductor, to control the temperature of the edge vials, the temperature controlled surface is closer to the surrounded edge vials than the surrounded center vials,
wherein the non-uniformity of the edge vials compared to the center vials during freezing and/or primary drying of product therein in the freeze dryer is reduced by adjusting the temperature of the temperature controlled surface.
2. The apparatus of claim 1 wherein the temperature controlled surface is a thermal emulator.
3. The apparatus of claim 1 wherein the temperature controlled surface is adjusted by programmed steps or by tracking a product temperature dynamically in response to changing temperatures or heat flows of at least one measured vial.
4. The apparatus of claim 1 wherein the thermal conductor is positioned between and in direct contact with the temperature controlled surface and the edge vials.
5. The apparatus of claim 1 wherein the temperature of the temperature controlled surface is adjusted by a circulating fluid, direct expansion of refrigerant, a Peltier device or forced air or gas.
6. The apparatus of claim 1 wherein the temperature controlled surface has a ring-like configuration surrounding the edge vials.
7. An apparatus for enabling a development freeze dryer containing a small sample of product in vials to simulate freezing and sublimation conditions of product in vials in a larger batch target freeze dryer, comprising:
a temperature controlled surface surrounding both outer edge vials and center vials, wherein the temperature controlled surface is in direct contact with or direct connection to outer edge vials in the development freeze dryer, or connected to the outer edge vials via a thermal conductor, the temperature controlled surface is closer to the surrounded outer edge vials than the surrounded center vials,
wherein conditions of center vials and/or outer edge vials of the larger batch target freeze dryer can be simulated by adjusting the temperature of the temperature controlled surface.
8. The apparatus of claim 7 wherein the temperature controlled surface is connected to the outer edge vials by the thermal conductor or is directly adjacent to the outer edge vials.
9. The apparatus of claim 8 wherein the thermal conductor is formed of a thermally conductive material.
10. The apparatus of claim 9 wherein the thermal conductor is formed of copper, stainless steel, aluminum, ceramic, paste, borosilicate glass and/or conductive rubber.
11. The apparatus of claim 9 wherein the thermal conductor is adjustable to provide adequate contact with the vials.
12. The apparatus of claim 9 wherein the temperature controlled surface is controlled by a circulating fluid, direct expansion of refrigerant, a Peltier device or forced air or gas.
13. The apparatus of claim 8 wherein the thermal conductor is a flexible membrane that can expand and contract for intimate contact with the outer edge vials or center vials.
14. The apparatus of claim 13 wherein the flexible membrane is filled with a thermally conductive fluid that is temperature controlled.
15. The apparatus of claim 7 wherein the temperature of the temperature controlled surface is adjusted by programmed steps or by tracking a product temperature dynamically in response to changing temperature or heat flows of at least one measured vial.
16. The apparatus of claim 7 further comprising:
a temperature controlled shelf; and
a heat flux sensor configured to measure and control thermal transfer between the temperature controlled shelf and at least one vial containing a product.
17. A method of enabling a development freeze dryer containing a small sample of product in vials to simulate freezing and sublimation conditions of product in vials in a larger batch target freeze dryer, comprising:
positioning a temperature controlled surface surrounding both edge vials and center vials, wherein the temperature controlled surface is in direct contact with or direct connection to edge vials in the development freeze dryer, or connected to the edge vials via a thermal conductor, the temperature controlled surface is closer to the surrounded edge vials than the surrounded center vials, and conditions of the center vials and/or the edge vials of the larger batch target freeze dryer can be simulated by adjusting the temperature of the temperature controlled surface.
18. The method of claim 17 wherein the thermal conductor is formed of a thermally conductive material.
19. The method of claim 18 further comprising controlling the temperature of the temperature controlled surface by programmed steps or by tracking a product temperature dynamically in response to changing temperature or heat flow of any measured vial.