Characterization of the Morphological Nature of Hollow Spray Dried Dispersion Particles Using X-ray Submicron-Computed Tomography

Past, current, and future: Application of image analysis in small molecule pharmaceutical development

The often-perceived limitations of image analysis have for many years impeded the widespread application of such systems as first line characterisation tools. Image analysis has, however, undergone a notable resurgence in the pharmaceutical industry fuelled by developments system capabilities and the desire of scientists to characterize the morphological nature of their particles more adequately. The importance of particle shape as well as size is now widely acknowledged. With the increasing use of modelling and simulations, and ongoing developments though the integration of machine learning and artificial intelligence, the utility of image analysis is increasing significantly driven by the richness of the data obtained. Such datasets provide means to circumvent the requirement to rely on less informative descriptors and enable the move towards the use of whole distributions. Combining the improved particle size and shape measurement and description with advances in modelling and simulations is enabling improved means to elucidate the link between particle and bulk powder properties. In addition to improved capabilities to describe input materials, approaches to characterize single components within multicomponent systems are providing scientists means to understand how their material may change during manufacture thus providing a means to link the behaviour of final dosage forms with the particle properties at the point of action. The aim is to provide an overview of image analysis and update readers with innovations and capabilities to other methods in the small molecule arena. We will also describe the use of AI for the improved analysis using image analysis.

Impact of Processing Methods on the Physico-chemical Properties of Posaconazole Amorphous Solid Dispersions

BACKGROUND & PURPOSE

Different methods have been exploited to generate amorphous solid dispersions (ASDs) of poorly water-soluble drugs. However, the impact of processing methods on drug stability and dissolution hasn't been studied extensively. The purpose of the current study is to investigate the impact of the two common ASD processing methods, hot-melt extrusion (HME) and spray drying, on the chemical/physical stability and supersaturation of Posaconazole (Posa) based ASDs.

METHODS & RESULTS

ASDs with 25% drug loading in hydroxypropylmethylcellulose acetate succinate were prepared using HME, and two types of spray dryers, a Procept Sprayer (ASD-Procept) and a Nano Sprayer (ASD-Nano). The relative physical stability of these ASDs upon exposure to heat and crystalline API seeding followed the order: ASD-Nano > ASD-Procept ≈HME. ASD-Procept and ASD-Nano showed similar chemical stability, slightly less stable than HME under 40°C/75%RH. All three ASDs demonstrated similar supersaturation induction times, and de-supersaturation kinetics with or without crystalline seeds.

CONCLUSIONS

Posa ASDs prepared via spray drying were chemically less stable compared with HME, which can be attributed to their smaller particle size and hollow structure allowing oxygen penetration. For ASD-Procept and HME, the detailed phase changes involving recrystallization of amorphous Posa and a solid-solid phase transition from Posa Form I to Form Ia during the seed-induced studies were proposed. Similar dissolution and supersaturation-precipitation kinetics of three Posa ASDs indicated that any residual nanocrystals in the bulk ASDs were not enough to induce crystallization to differentiate ASDs made by three processing methods.

Antioxidant Potential of Spray- and Freeze-Dried Extract from Oregano Processing Wastes, Using an Optimized Ultrasound-Assisted Method

Origanum vulgare is recognized worldwide for its numerous applications, in the food industry and beyond. However, the extraction of its essential oils generates a significant amount of waste. The aim of this research was to achieve the valorization of solid waste from oregano hydro-distillation, by (i) optimizing the ultrasound extraction of antioxidants, (ii) evaluating the effect of spray and freeze drying on the extract's physicochemical properties, and (iii) characterizing the obtained powder by its antioxidant capacity. A central composite design of experiments was used to optimize the sample/solvent ratio, ethanol/water ratio, and extraction time. The extract was analyzed for its antioxidant potential by determining the percentage of DPPH inhibition, FRAP, and total phenolic content (TPC). The GAB model best fit the data for the moisture sorption isotherm of the resulting powder. The antioxidant activity of the powders was tested in a ground-beef food system. The TPC was maximized at times longer than 58 min, a sample/solvent ratio between 0.058 and 0.078, and a ratio of ethanol/water around 1. Neither drying method significantly affected the antioxidant properties of the extract, even though the resulting powders from each showed a different morphology (determined using SEM). Encapsulation with maltodextrin protected the spray-dried extract during a 6-month storage period. Powders from both drying methods equally retarded lipid oxidation, and were comparable to the synthetic antioxidant BHT. It is concluded that oregano processing waste is a potent source of antioxidants, and that its dried extract, via an ultrasound-assisted process, can potentially be used as a natural alternative to synthetic antioxidants.

Multiscale X-ray imaging and characterisation of pharmaceutical dosage forms

A correlative, multiscale imaging methodology for visualising and quantifying the morphology of solid dosage forms by combining ptychographic X-ray computed nanotomography (PXCT) and scanning small- and wide-angle X-ray scattering (S/WAXS) is presented. The methodology presents a workflow for multiscale analysis, where structures are characterised from the nanometre to millimetre regime. Here, the method is demonstrated by characterising a hot-melt extruded, partly crystalline, solid dispersion of carbamazepine in ethyl cellulose. Characterisation of the morphology and solid-state phase of the drug in solid dosage forms is central as this affects the performance of the final formulation. The 3D morphology was visualised at a resolution of 80 nm over an extended volume through PXCT, revealing an oriented structure of crystalline drug domains aligned in the direction of extrusion. Scanning S/WAXS, showed that the nanostructure is similar over the cross section of the extruded filament, with minor radial changes in domain sizes and degree of orientation. The polymorphic forms of carbamazepine were qualified with WAXS, showing a heterogeneous distribution of the metastable forms I and II. This demonstrates the methodology for multiscale structural characterization and imaging to enable a better understanding of the relationships between morphology, performance, and processing conditions of solid dosage forms.

Determination of Particle Size Distributions of Bulk Samples Using Micro-Computed Tomography and Artificial Intelligence

The knowledge of product particle size distribution (PSD) in crystallization processes is of high interest for the pharmaceutical and fine chemical industries, as well as in research and development. Not only can the efficiency of crystallization/production processes and product quality be increased but also new equipment can be qualitatively characterized. A large variety of analytical methods for PSDs is available, most of which have underlying assumptions and corresponding errors affecting the measurement of the volume of individual particles. In this work we present a method for the determination of particle volumes in a bulk sample via micro-computed tomography and the application of artificial intelligence. The particle size of bulk samples of sucrose were measured with this method and compared to classical indirect measurement methods. Advantages of the workflow are presented.

Assessing the Interrelationship of Microstructure, Properties, Drug Release Performance, and Preparation Process for Amorphous Solid Dispersions Via Noninvasive Imaging Analytics and Material Characterization

PURPOSE

The purpose of this work is to evaluate the interrelationship of microstructure, properties, and dissolution performance for amorphous solid dispersions (ASDs) prepared using different methods.

METHODS

ASD of GDC-0810 (50% w/w) with HPMC-AS was prepared using methods of spray drying and co-precipitation via resonant acoustic mixing. Microstructure, particulate and bulk powder properties, and dissolution performance were characterized for GDC-0810 ASDs. In addition to application of typical physical characterization tools, we have applied X-Ray Microscopy (XRM) to assess the contribution of microstructure to the characteristics of ASDs and obtain additional quantification and understanding of the drug product intermediates and tablets.

RESULTS

Both methods of spray drying and co-precipitation produced single-phase ASDs. Distinct differences in microstructure, particle size distribution, specific surface area, bulk and tapped density, were observed between GDC-0810 spray dried dispersion (SDD) and co-precipitated amorphous dispersion (cPAD) materials. The cPAD powders prepared by the resonant acoustic mixing process demonstrated superior compactibility compared to the SDD, while the compressibility of the ASDs were comparable. Both SDD powder and tablets showed higher in vitro dissolution than those of cPAD powders. XRM calculated total solid external surface area (S_A) normalized by calculated total solid volume (S_V) shows a strong correlation with micro dissolution data.

CONCLUSION

Strong interrelationship of microstructure, physical properties, and dissolution performance was observed for GDC-0810 ASDs. XRM image-based analysis is a powerful tool to assess the contribution of microstructure to the characteristics of ASDs and provide mechanistic understanding of the interrelationship.

Investigation of Quantitative X-ray Microscopy for Assessment of API and Excipient Microstructure Evolution in Solid Dosage Processing

Assessment and understanding of changes in particle size of active pharmaceutical ingredients (API) and excipients as a function of solid dosage form processing is an important but under-investigated area that can impact drug product quality. In this study, X-ray microscopy (XRM) was investigated as a method for determining the in situ particle size distribution of API agglomerates and an excipient at different processing stages in tablet manufacturing. An artificial intelligence (AI)-facilitated XRM image analysis tool was applied for quantitative analysis of thousands of individual particles, both of the API and the major filler component of the formulation, microcrystalline cellulose (MCC). Domain size distributions for API and MCC were generated along with the calculation of the porosity of each respective component. The API domain size distributions correlated with laser diffraction measurements and sieve analysis of the API, formulation blend, and granulation. The XRM analysis demonstrated that attrition of the API agglomerates occurred secondary to the granulation stage. These results were corroborated by particle size distribution and sieve potency data which showed generation of an API fines fraction. Additionally, changes in the XRM-calculated size distribution of MCC particles in subsequent processing steps were rationalized based on the known plastic deformation mechanism of MCC. The XRM data indicated that size distribution of the primary MCC particles, which make up the larger functional MCC agglomerates, is conserved across the stages of processing. The results indicate that XRM can be successfully applied as a direct, non-invasive method to track API and excipient particle properties and microstructure for in-process control samples and in the final solid dosage form. The XRM and AI image analysis methodology provides a data-rich way to interrogate the impact of processing stresses on API and excipients for enhanced process understanding and utilization for Quality by Design (QbD).