Study of the Individual Contributions of Ice Formation and Freeze-Concentration on Isothermal Stability of Lactate Dehydrogenase during Freezing

Investigations on Polyplex Stability During the Freezing Step of Lyophilization Using Controlled Ice Nucleation—The Importance of Residence Time in the Low-Viscosity Fluid State

“…This is in accordance with literature, in which an increase in the ice surface area by nearly 50% is reported when the ice-nucleation temperature was decreased from −1 • C to −11 • C. 34 Moreover, the observed increase of the SSA per sample vial with increasing solid content also agrees well with literature. 23 For proteins, it is well known that surface-induced denaturation can be damaging 35 and that the difference in ice-nucleation temperature can greatly influence protein stability. 23,36 Here, as one possibility, it is speculated that the mechanism involves very strong electric fields that are generated during ice crystallization due to preferential incorporation of one ionic species into the ice.…”

“…23 For proteins, it is well known that surface-induced denaturation can be damaging 35 and that the difference in ice-nucleation temperature can greatly influence protein stability. 23,36 Here, as one possibility, it is speculated that the mechanism involves very strong electric fields that are generated during ice crystallization due to preferential incorporation of one ionic species into the ice. 24,37 The strength of the electric field depends on the freezing rate, the type of solvent, and the type and concentration of ionic species present in solution.…”

“…19 However, Bhatnagar et al 23 showed that ice formation and not freeze concentration is the critical destabilizing factor during freezing of lactate dehydrogenase. Thus, this comparison shows that an optimized freezing procedure cannot simply be directly transferred to another pharmaceutical active ingredient.…”

“…From these results, the average SSA (m 2 /g) along with the standard deviation was calculated. To include the effect of variable ice surface area in samples of equal volumes but of variable sucrose levels, the absolute SSA (m 2 / 100 mL) 23 was calculated by absolute SSA m 2 100 mL = SSA m 2 g · % solute g 100 mL (1)…”

Lyophilization Process Design and Development Using QbD Principles

“…During freezing, stability problems may arise due to pH changes resulting from crystallization of certain buffer components (Gomez et al 2001), cryoconcentration, ice-liquid interface (Bhatnagar et al 2007(Bhatnagar et al , 2008, phase separation (Izutsu et al 2005;Padilla and Pikal 2010), and cold denaturation (Tang and Pikal 2005). Formulations used for freeze-drying exhibit super-cooling tendencies and thermal events such as eutectic or glass transitions (Pikal 1990).…”