The study of Phase Separation in Amorphous Freeze-Dried Systems, Part 2: Investigation of Raman Mapping as a Tool for Studying Amorphous Phase Separation in Freeze-Dried Protein Formulations

Impact of Heat Treatment on the Physical Properties of Noncrystalline Multisolute Systems Concentrated in Frozen Aqueous Solutions

“…[1][2][3][4][5] The growing clinical significance of therapeutic proteins and liposomes makes their miscibility with nonreducing disaccharides (e.g., sucrose and trehalose) in frozen solutions and subsequently dried solids an intriguing topic because their thermodynamic and kinetic stabilization mechanisms, namely water-substituting direct molecular interactions and mobility-limiting embedment in glass-state solids, both require the mixing of heterogeneous molecules. [6][7][8][9][10] Assessing and controlling the component miscibility in noncrystalline solid formulations, however, are often challenging. Thermal analysis and several spectroscopic methods have been applied to estimate the miscibility of ingredients in colyophilized solids and molecular dispersion solid formulations.…”

“…Thermal analysis and several spectroscopic methods have been applied to estimate the miscibility of ingredients in colyophilized solids and molecular dispersion solid formulations. 6,[8][9][10][11] Profiles of glass transition temperatures (T g s) indicate nonideal mixing of colyophilized disaccharides and polymers (e.g., trehalose and dextran) in some solids. 9,10 The local inhomogeneity of a disaccharide and a polymer [e.g., polyvinylpyrrolidone (PVP) and lysozyme] in amorphous freeze-dried or hot melt-extruded mixture solids has also been reported in studies using novel spectroscopic techniques [e.g., microscopic near-infrared (NIR) and Raman imaging, X-ray powder diffraction (XRPD) coupled with computation of pair distribution functions].…”

Heterogeneity of Protein Environments in Frozen Solutions and in the Dried State

“…A potential protein/polymer phase separation in human brain-derived neurotropic factor (BDNF) and BDNF-polyethylene glycol (PEG) co-lyophilized with dextran was suggested based on scanning electron microscopy [26]. Additional evidences of phase separation between proteins and polymers were obtained using Raman mapping, which detected amorphous/amorphous phase separation between a protein and a lyoprotector, e.g., in lactoglobulin-dextran system [27][28][29]. It was also shown that trehalose had a greater propensity for phase separation from protein than sucrose, with phase separation detected for lysozyme-trehalose and lactoglobulin-trehalose (but not for protein-sucrose) systems.…”

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).…”