Table 2 List of critical process parameters and control limits for freeze drying [Reproduced from Radhakrishnan et al. [42] with kind permission of the copyright holder, Springer, Cham]
Freeze-drying steps | Parameter | Control limits |
|---|---|---|
Freezing | Freezing temperature of shelf | Not more than − 40 °C |
Primary drying | Chamber pressure | Below 150 microns |
Primary drying | Shelf temperature | Not more than + 35 °C |
Primary drying | Hold time | Not less than 18Â h |
Secondary drying | Shelf temperature | Between 35 and 65 °C |
Secondary drying | Hold time | Not less than 5Â h |