Real-time observation of protein aggregates in pharmaceutical formulations using liquid cell electron microscopy.

Understanding the properties of protein-based therapeutics is a common goal of biologists and physicians. Technical barriers in the direct observation of small proteins or therapeutic agents can limit our knowledge of how they function in solution and in the body. Electron microscopy (EM) imaging performed in a liquid environment permits us to peer into the active world of cells and molecules at the nanoscale. Here, we employ liquid cell EM to directly visualize a protein-based therapeutic in its native conformation and aggregate state in a time-resolved manner. In combination with quantitative analyses, information from this work contributes new molecular insights toward understanding the behaviours of immunotherapies in a solution state that mimics the human body.

Application of imaging based tools for the characterisation of hollow spray dried amorphous dispersion particles.

The aim of this study was to investigate novel approaches to determine spray dried dispersion (SDD) specific particle characteristics through the use of imaging based technologies. The work demonstrates approaches that can be applied in order to access quantitative approximations for powder characteristics for hollow particles, such as SDD. Cryo-SEM has been used to measure the solid volume fraction and/or particle density of SDD particles. Application of this data to understand the impact of spray drying process conditions on SDD powder properties, and their impact on processability and final dosage form quality were investigated. The use of data from a Morphologi G3 image based particle characterisation system was also examined in order to explain both the propensity and extent of attrition within a series of SDD samples, and also demonstrate the use of light transmission data to assess the relative wall thickness of SDD particles. Such approaches demonstrate a means to access potentially useful information that can be linked to important particle characteristics for SDD materials which, in addition to the standard bulk powder measurements such as bulk density, may enable a better understanding of such materials and their impact on downstream processability and final dosage form acceptability.

Use of enthalpy and Gibbs free energy to evaluate the risk of amorphous formation.

The control of crystalline and amorphous phases is important during the development of a new drug candidate. Our approach begins with an understanding of the thermodynamics of these two phases. We have developed a quantitative yet practical work flow consisting of three steps towards the analysis of the risk of amorphous material formation. First, we derive the thermodynamic equations to calculate the enthalpy, Gibbs free energy, and the solubility of each phase and their differences as a function of temperature. The enthalpy for each crystalline drug substance at its melting point is selected as the reference state to enable a consistent approach for all analysis. Second, we use data from DSC measurements and the derived thermodynamic equations to construct the enthalpy, Gibbs free energy and solubility diagrams so as to compare the characteristics of these two phases. Finally, we use the results of these calculations to evaluate the potential risk of crystalline-to-amorphous phase conversion during processing of either the drug substance or the drug product. In addition, the impact of amorphous formation on solubility is evaluated. Two drug candidates are used to illustrate this workflow for risk analysis.