Proof-of-Concept in Developing a 45% Drug Loaded Amorphous Nanoparticle Formulation

Amorphous solid dispersion (ASD) is an enabling approach utilized to deliver poorly soluble compounds. ASDs can spontaneously generate drug-rich amorphous nanoparticles upon dissolution, which can act as a reservoir for maintaining supersaturation during oral absorption. But, conventional ASDs are often limited in drug loadings to < 20 %. For indications where the dose is high, this can translate into a significant pill burden. The aim of this research was to develop a high drug loading (DL) amorphous nanoparticle (ANP) formulation that can release the drug-rich nanoparticles into solution upon contact with aqueous environment. Nanoparticles were directly engineered using solvent/anti-solvent precipitation. The obtained nanoparticle suspension was then concentrated followed by solidification to a re-dispersible amorphous dosage form using spray drying or lyophilization. The impact of process variables was studied using dynamic light scattering (DLS), scanning electron microscopy (SEM), high performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). It was observed that spray drying led to a non-re-dispersible formulation. Sucrose and trehalose containing lyocakes resulted in re-dispersible formulations. The trehalose containing lyocakes, in a dog study, gave comparable performance to the reference tablet in the fasted state but lower area under the curve (AUC) in fed state.

Polymorphism and surface diversity arising from stress-induced transformations – the case of multicomponent forms of carbamazepine

Stress-induced transformations of labile multicomponent organic solids may have a significant impact on industrial manufacturing processes, for example, in the pharmaceutical field. This study considers 15 carbamazepine (CBZ) multicomponent crystal forms, with the aim of identifying the structural and surface features that drive the outcome of thermal stress-induced transformations. Analysis of the crystal structures, and specifically the degree of similarity with the CBZ polymorphs produced by desolvation-like processes, identifies some degree of correlation between structural features. In particular, mutually exclusive supramolecular motifs identified previously within CBZ crystal structures are frequently (but not invariably) preserved, and thereby provide some indication of the anticipated polymorphic outcome. This is broadly consistent with established models relating reactant and product crystal phases. Some of the CBZ multicomponent materials show surface modifications indicative of the formation of a liquid intermediate phase, which provides an alternative dissolution/recrystallization mechanism and different polymorphic outcomes compared to the direct solid–solid transformation pathway. Other cases show intermediates of varying stoichiometry and instances of chemical decomposition. Hence, the product of thermal decomposition is frequently affected by the physical properties of the coformer, such as boiling point and reactivity. This can lead to a dependence on experimental conditions, especially when events such as recrystallization, chemical decomposition of the coformer, solubilization and peritectic melting occur concomitantly. This study highlights that the overall picture is complex, even within this series of closely related materials.

Predictive models of lyophilization process for development, scale-up/tech transfer and manufacturing

Scale-up and technology transfer of lyophilization processes remains a challenge that requires thorough characterization of the laboratory and larger scale lyophilizers. In this study, computational fluid dynamics (CFD) was employed to develop computer-based models of both laboratory and manufacturing scale lyophilizers in order to understand the differences in equipment performance arising from distinct designs. CFD coupled with steady state heat and mass transfer modeling of the vial were then utilized to study and predict independent variables such as shelf temperature and chamber pressure, and response variables such as product resistance, product temperature and primary drying time for a given formulation. The models were then verified experimentally for the different lyophilizers. Additionally, the models were applied to create and evaluate a design space for a lyophilized product in order to provide justification for the flexibility to operate within a certain range of process parameters without the need for validation.

Solving the inverse problem for aggregation in activated sludge flocculation using a population balance framework

Many systems contain populations of individuals. Often, they are regarded as a lumped phase, which might, for some applications, lead to inadequate model predictive power. An alternative framework, Population Balance Models, has been used here to describe such a system, activated sludge flocculation in which particle size is the property one wants to model. An important problem to solve in population balance modelling is to determine the model structure that adequately describes experimentally obtained data on for instance, the time evolution of the floc size distribution. In this contribution, an alternative method based on solving the inverse problem is used to recover the model structure from the data. In this respect, the presence of similarity in the data simplifies the problem significantly. Similarity was found and the inverse problem could be solved. A forward simulation then confirmed the quality of the model structure to describe the experimental data.