Physicohemical characterization of the freezing behavior of mannitol-human serum albumin formulations

Abstract

The goal of the study was to analyze the impact of human serum albumin (HSA) quality (stabilized or nonstabilized HSA), the addition of NaCl, and the HSA stabilizers Naoctanoate and Na-N-acetyltryptophanate on the freezing behavior of mannitol-HSA formulations. The focus was on crystallization, Tg' (glass transition temperature of the maximally freeze-concentrated phase), and Tc (collapse temperature). Differential scanning calorimetry (DSC), cryomicroscopy, and low-temperature x-ray powder diffraction (LTXRD) were used to study the frozen state. In mannitol-HSA formulations, mannitol crystallization was inhibited and Tg' lowered to a greater extent by stabilized HSA (containing Na-octanoate, Na-N-acetyltryptophanate, and NaCl) than by unstabilized HSA. Detailed DSC and LTXRD studies showed that in the concentrations used for stabilizing HSA, NaCl led to changes in the freezing behavior, an effect that was less pronounced for the other stabilizers. NaCl further lowered the Tc, which was determined by cryomicroscopy. As the freezing behavior governs the lyophilization process, the changes have to be taken into consideration for the development of a lyophilization cycle, to avoid collapse and instabilities.

Enhancing Lysozyme Loading in Powderized Liposomes by Controlling Encapsulation Processes

“…However, D‐mannitol exhibited comparatively low protective effect on the liposomes during the freeze‐drying procedure. This might be attributed to the partial crystallization of D‐mannitol at temperature between −30 and −16°C during the freezing process, as reported in several studies, which could damage the physical structure of the liposomes …”

“…This might be attributed to the partial crystallization of D-mannitol at temperature between −30 and −16 C during the freezing process, as reported in several studies, which could damage the physical structure of the liposomes. [22][23][24] Physical Stability Test of Lysozyme-loaded Liposomes. The physical stability of liposomes before and after freezedrying was evaluated by reconstituting the liposomes in distilled water and measuring particle characteristics such as average particle size, polydispersity index and zetapotential value for 7 days.…”

Influence of freezing down to 77.15 K on structure and antioxidant power of some proteins

“…Albumin is a globular subunit protein with domain structure (63 kDa molecular mass). Freezing of albumin solution also results in molecule aggregation [10]. Equine heart Cyt C is a small globular protein with 12 kDa molecular mass when being in oxidized form.…”

Development of a Lyophilization Process for Long-Term Storage of Albumin-Based Perfluorodecalin-Filled Artificial Oxygen Carriers

“…This quotient could not be reached with the nanocapsule suspension by itself, even though a higher amount of the suspension lead to a better quotient. This is possibly due to the fact that a higher amount of the nanocapsule suspension leads to a higher content of free HSA, which functions as a cryoprotectant [25,26]. Yet, an optimal quotient could not be achieved.…”

“…The volume of the nanocapsule suspension and, therefore, the resulting nanocapsule concentration was chosen as a further factor, because due to freeze concentration, an influence on the HD was expected. On the other hand, due to the preparation process, the suspensions contain free HSA besides the HSA nanocapsules and free HSA can act as a cryoprotective excipient [26]. The concentration of the free HSA varies with the volume of the nanocapsule suspension used for the filling of the vials.…”