Determining the Impact of Roller Compaction Processing Conditions on Granulate and API Properties: Impact of Formulation API Load.

Previous work demonstrated that roller compaction of a 40%w/w theophylline-loaded formulation resulted in granulate consisting of un-compacted fractions which were shown to constitute between 34 and 48%v/v of the granulate dependent on processing conditions. The active pharmaceutical ingredient (API) primary particle size within the un-compacted fraction was also shown to have undergone notable size reduction. The aim of the current work was to test the hypothesis that the observations may be more indicative of the relative compactability of the API due to the formulation being above the percolation threshold. This was done by assessing the impact of varied API loads in the formulation on the non-granulated fraction of the final granulate and the extent of attrition of API particles within the non-granulated fraction. The influence of processing conditions for all formulations was also investigated. The results verify that the observations, both of this study and the previous work, are not a consequence of exceeding the percolation threshold. The volume of un-compacted material within the granulate samples was observed to range between 34.7 and 65.5% depending on the API load and roll pressure, whilst the API attrition was equivalent across all conditions.

Morphological distribution mapping: Utilisation of modelling to integrate particle size and shape distributions.

The aim of this work was to develop approaches to utilize whole particle distributions for both particle size and particle shape parameters to map the full range of particle properties in a curated dataset. It is hoped that such an approach may enable a more complete understanding of the particle landscape as a step towards improving the link between particle properties and processing behaviour. A 1-dimensional principal component analysis (PCA) approach was applied to create a 'morphological distribution landscape'. A dataset of imaged APIs, intermediates and excipients encompassing particle size, particle shape (elongation, length and width) and distribution shape was curated between 2008 and 2022. The curated dataset encompassed over 200 different materials, which included over 150 different APIs, and approximately 3500 unique samples. For the purposes of the current work, only API samples were included. The morphological landscape enables differentiation of materials of equivalent size but varying shape and vice versa. It is hoped that this type of approach can be utilised to better understand the influence of particle properties on pharmaceutical processing behaviour and thereby enable scientists to leverage historical knowledge to highlight and mitigate risks associated to materials of similar morphological nature.

Particle Property Characterization and Data Curation for Effective Powder Property Modeling in the Pharmaceutical Industry.

Computational modeling, machine learning, and statistical data analysis are increasingly utilized to mitigate chemistry, manufacturing, and control failures related to particle properties in solid dosage form manufacture. Advances in particle characterization techniques and computational approaches provide unprecedented opportunities to explore relationships between particle morphology and drug product manufacturability. Achieving this, however, has numerous challenges such as producing and appropriately curating robust particle size and shape data. Addressing these challenges requires a harmonized strategy from material sampling practices, characterization technique selection, and data curation to provide data sets which are informative on material properties. Herein, common sources of error in particle characterization and data compression are reviewed, and a proposal for providing robust particle morphology (size and shape) data to support modeling efforts, approaches for data curation, and the outlook for modeling particle properties are discussed.

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

Graphical Abstract.

Determining the Impact of Roller Compaction Processing Conditions on Granule and API Properties.

The attrition of drug particles during the process of dry granulation, which may (or may not) be incorporated into granules, could be an important factor in determining the subsequent performance of that granulation, including key factors such as sticking to punches and bio-performance of the dosage form. It has previously been demonstrated that such attrition occurs in one common dry granulation process train; however, the fate of these comminuted particles in granules was not determined. An understanding of the phenomena of attrition and incorporation into granule will improve our ability to understand the performance of granulated systems, ultimately leading to an improvement in our ability to optimize and model the process. Unique feeding mechanisms, geometry, and milling systems of roller compaction equipment mean that attrition could be more or less substantial for any given equipment train. In this work, we examined attrition of API particles and their incorporation into granule in an equipment train from Gerteis, a commonly used equipment train for dry granulation. The results demonstrate that comminuted drug particles can exist free in post-milling blends of roller compaction equipment trains. This information can help better understand the performance of the granulations, and be incorporated into mechanistic models to optimize such processes.

A Proposal for an Alternative Approach to Particle Size Method Development During Early-Stage Small Molecule Pharmaceutical Development.

Particle size analysis in the pharmaceutical industry has long been a source of debate regarding how best to define measurement accuracy; the degree to which the result of a measurement or calculation conforms to the true value. Defining a "true" value for the size of a particle can be challenging as the output of its measurement will differ because of variations in measurement approaches, instrumental differences and calculation methods. Consequently, for "real" particles, a universal "true" value does not exist and accuracy is therefore not a definable characteristic. Accordingly, precision is then a measure of the ability to reproducibly achieve a measurement of unknown relevance. This article proposes, in place of accuracy, a means to define the "appropriateness" of a measurement in line with the critical quality attributes (CQA) of the material being characterized. The decision as to whether the measurement is correct should involve a link to the CQA; that is, correlation should be demonstrated, without which the measured particle size cannot be defined as a critical material attribute. Correspondingly, methods should also be able to provide sufficient precision to demonstrate discrimination relating to variation in the CQA. The benefits and challenges of this approach are discussed.

Preoperative Blood Management Strategy for Elective Hip and Knee Arthroplasty.

To improve quality and outcomes, a preoperative anemia clinic (PAC) was established to screen, evaluate, and manage preoperative anemia. A retrospective review of primary and revision hip and knee arthroplasty patients from August 2013 to September 2017 was conducted. Patients at "high risk" for transfusion were referred to PAC for treatment with iron, erythropoietin, or both based on anemia type. Preoperative anemia clinic referred patients were compared with a 1:3 historic propensity-matched control set of patients to help determine impact of PAC. Forty PAC patients were compared with 120 control patients. Among PAC patients, 26 (63.41%) received iron only, 3 (7.32%) received erythropoietin (EPO) only, and 12 (29.27%) received both. Preoperative hemoglobin significantly increased in the treatment group (median [interquartile range] 10.9 g/dl [10.3-11.2] vs. 12.0 g/dl [11.2-12.7]; p < .001). Four PAC patients (10.00%) received red blood cell transfusions compared with 29 (24.17%) from matched controls (p = .055). In addition, the PAC cohort had higher postoperative nadir hemoglobin levels (mean [SD] 9.7 g/dl [1.31] vs. 8.7 g/dl [1.25]; p < .001). High-risk patients appropriately treated with iron and/or EPO before surgery demonstrate a significant increase in preoperative hemoglobin, trend toward decrease perioperative transfusion, and increased hemoglobin levels postoperatively compared with matched controls.

Enhanced Understanding of Pharmaceutical Materials Through Advanced Characterisation and Analysis.

The impact of pharmaceutical materials properties on drug product quality and manufacturability is well recognised by the industry. An ongoing effort across industry and academia, the Manufacturing Classification System consortium, aims to gather the existing body of knowledge in a common framework to provide guidance on selection of appropriate manufacturing technologies for a given drug and/or guide optimization of the physical properties of the drug to facilitate manufacturing requirements for a given processing route. Simultaneously, material scientists endeavour to develop characterisation methods such as size, shape, surface area, density, flow and compactibility that enable a stronger understanding of materials powder properties. These properties are routinely tested drug product development and advances in instrumentation and computing power have enabled novel characterisation methods which generate larger, more complex data sets leading to a better understanding of the materials. These methods have specific requirements in terms of data management and analysis. An appropriate data management strategy eliminates time-consuming data collation steps and enables access to data collected for multiple methods and materials simultaneously. Methods ideally suited to extract information from large, complex data sets such as multivariate projection methods allow simpler representation of the variability contained within the data and easier interpretation of the key information it contains. In this review, an overview of the current knowledge and challenges introduced by modern pharmaceutical material characterisation methods is provided. Two case studies illustrate how the incorporation of multivariate analysis into the material sciences workflow facilitates a better understanding of materials.

Determination of process variables affecting drug particle attrition withinmulti-component blends during powder feed transmission.

The aim of this study was to determine the location of attrition of formulated API particles within a powder feed system using a Morphologi G3-ID system, an image analyzer with integrated Raman capability enabling classification of particles with respect to their chemistry, to extract the API size distribution from the blended sample. The study also aimed to investigate the impact of other process variables, such as feed screw speed, on the extent of attrition observed. The study demonstrated that attrition occurs in two zones of the powder feed system, at the bottom of the hopper at the interface with the feed screw, and also within the feed screw itself. In the situation of the attrition at the bottom of the hopper variations in the hopper fill level were not observed to change the extent of attrition observed. Variation of the feed screw speed was observed to affect the extent of API attrition, with the particle size within the formulation observed to decrease with increasing speed. The findings highlight that an understanding of the impact of unit processes, and variations in the associated processing conditions, is vital in order to fully understand the behavior and performance of pharmaceutical dosage forms.

Airway Management in a Patient with Wolf-Hirschhorn Syndrome.

We present a case of a 3-month-old female with Wolf-Hirschhorn syndrome (WHS) undergoing general anesthesia for laparoscopic gastrostomy tube placement with a focus on airway management. WHS is a rare 4p microdeletion syndrome resulting in multiple congenital abnormalities, including craniofacial deformities. Microcephaly, micrognathia, and glossoptosis are common features in WHS patients and risk factors for a pediatric airway that is potentially difficult to intubate. We discuss anesthesia strategies for airway preparation and management in a WHS patient requiring general anesthesia with endotracheal intubation.

Application of X-ray microtomography for the characterisation of hollow polymer-stabilised spray dried amorphous dispersion particles.

The aim of this study was to investigate the capability of X-ray microtomography to obtain information relating to powder characteristics such as wall thickness and solid volume fraction for hollow, polymer-stabilised spray dried dispersion (SDD) particles. SDDs of varying particle properties, with respect to shell wall thickness and degree of particle collapse, were utilised to assess the capability of the approach. The results demonstrate that the approach can provide insight into the morphological characteristics of these hollow particles, and thereby a means to understand/predict the processability and performance characteristics of the bulk material. Quantitative assessments of particle wall thickness, particle/void volume and thereby solid volume fraction were also demonstrated to be achievable. The analysis was also shown to be able to qualitatively assess the impact of the drying rate on the morphological nature of the particle surfaces, thus providing further insight into the final particle shape. The approach demonstrated a practical means to access potentially important particle characteristics for SDD materials which, in addition to the standard bulk powder measurements such as particle size and bulk density, may enable a better understanding of such materials, and their impact on downstream processability and dosage form performance.

Measuring the sticking of mefenamic acid powders on stainless steel surface.

This study proposes an approach for quantifying the amount of pharmaceutical powder adhering (quality attribute) to the metals surfaces. The effect of surface roughness (detrimental attribute) on the amount of powder sticking to a stainless steel surface for a model pharmaceutical material is also qualitatively determined. Methodology to quantify powder adhesion to surfaces utilises a texture analyser and HPLC. The approach was validated to qualitatively investigate effect of metal surface roughness on adhesion of mefenamic acid. An increase in metal surface roughness resulted in an increase in cohesion. By increasing the average roughness from 289nm to 407nm, a 2.5 fold increase in amount adhering to metal was observed, highlighting the role of surface roughness on adhesion. The simplicity in experimental design with no requirement of specialised equipment and operational ease makes the approach very easy to adopt. Further, ease in interpreting results makes this methodology very attractive.

Investigation into process-induced de-aggregation of cohesive micronised API particles.

The aim of this study was to assess the impact of unit processes on the de-aggregation of a cohesive micronised API within a pharmaceutical formulation using near-infrared chemical imaging. The impact on the primary API particles was also investigated using an image-based particle characterization system with integrated Raman analysis. The blended material was shown to contain large, API rich domains which were distributed in-homogeneously across the sample, suggesting that the blending process was not aggressive enough to disperse aggregates of micronised drug particles. Cone milling, routinely used to improve the homogeneity of such cohesive formulations, was observed to substantially reduce the number and size of API rich domains; however, several smaller API domains survived the milling process. Conveyance of the cone milled formulation through the Alexanderwerk WP120 powder feed system completely dispersed all remaining aggregates. Importantly, powder feed transmission of the un-milled formulation was observed to produce an equally homogeneous API distribution. The size of the micronised primary drug particles remained unchanged during powder feed transmission. These findings provide further evidence that this powder feed system does induce shear, and is in fact better able to disperse aggregates of a cohesive micronised API within a blend than the blend-mill-blend step.

Application of image-based particle size and shape characterization systems in the development of small molecule pharmaceuticals.

With the introduction of Quality by Design (QbD) to the pharmaceutical industry, there has been an increased focus on understanding the nature of particles and composites, with the aim of understanding and modeling how they interact in complex systems, leading to robust dosage forms. Particle characterization tools have evolved and now enable a greater level of understanding of powder systems and blends. Tools that can elucidate the size and shape of particulate systems can provide significantly more information about the nature of the particles being analyzed, than a conventional particle size measurement. Although accurate size and shape analysis has always been regarded as the "gold standard" in understanding the nature of particulate systems, neither imaging systems nor IT infrastructure was sufficiently developed to allow this to be performed with sufficient accuracy in a timely manner. The aim of this review is to provide an insight into developments in the field of size and shape analysis of pharmaceutical systems, and how these can now realistically be used as robust development tools. Examples of current uses of such technologies will be explored as well as investigating future applications such as combined image/spectroscopic analyses to track single components within blended systems.

Development of a material sparing bulk density test comparable to a standard USP method for use in early development of API's.

Bulk density can be a key indicator of performance, and may influence choice of formulation route of materials in pharmaceutical development. During early development, the cost of API's can be expensive and the availability of material for powder property analysis is limited. The aim of this work was to investigate a suitable small-scale, low material requirement, bulk density test which would provide comparable data to the recommended large volume USP test. Materials with a range of morphological characteristics typically seen in the pharmaceutical industry were assessed to ensure that methods were suitably robust. It was found that the USP II "low volume" test does not give equivalent results to other tests in the USP, across the range of materials. An alternative test based on the FT4 powder rheometer at a scale of 25 mL gave results equivalent to the large volume USP I standard test. The use of smaller 10-mL methods was also found to give acceptable results for materials that were considered well-behaved but were more variable with difficult to handle materials with low bulk density.

The secondary drying and the fate of organic solvents for spray dried dispersion drug product.

PURPOSE: To understand the mechanisms of secondary drying of spray-dried dispersion (SDD) drug product and establish a model to describe the fate of organic solvents in such a product. METHODS: The experimental approach includes characterization of the SDD particles, drying studies of SDD using an integrated weighing balance and mass spectrometer, and the subsequent generation of the drying curve. The theoretical approach includes the establishment of a Fickian diffusion model. RESULTS: The kinetics of solvent removal during secondary drying from the lab scale to a bench scale follows Fickian diffusion model. Excellent agreement is obtained between the experimental data and the prediction from the modeling. CONCLUSIONS: The diffusion process is dependent upon temperature. The key to a successful scale up of the secondary drying is to control the drying temperature. The fate of primary solvents including methanol and acetone, and their potential impurity such as benzene can be described by the Fickian diffusion model. A mathematical relationship based upon the ratio of diffusion coefficient was established to predict the benzene concentration from the fate of the primary solvent during the secondary drying process.

Effect of crystal habits on the surface energy and cohesion of crystalline powders.

The role of surface properties, influenced by particle processing, in particle-particle interactions (powder cohesion) is investigated in this study. Wetting behaviour of mefenamic acid was found to be anisotropic by sessile drop contact angle measurements on macroscopic (>1cm) single crystals, with variations in contact angle of water from 56.3° to 92.0°. This is attributed to variations in surface chemical functionality at specific facets, and confirmed using X-ray photoelectron spectroscopy (XPS). Using a finite dilution inverse gas chromatography (FD-IGC) approach, the surface energy heterogeneity of powders was determined. The surface energy profile of different mefenamic acid crystal habits was directly related to the relative exposure of different crystal facets. Cohesion, determined by a uniaxial compression test, was also found to relate to surface energy of the powders. By employing a surface modification (silanisation) approach, the contribution from crystal shape from surface area and surface energy was decoupled. By "normalising" contribution from surface energy and surface area, needle shaped crystals were found to be ∼2.5× more cohesive compared to elongated plates or hexagonal cuboid shapes crystals.

Monitoring process induced attrition of drug substance particles within formulated blends.

The aim of the study was to investigate the impact of unit processing steps such as blending, cone milling and powder feeding systems on the particle size of a formulated API. The particle properties of a single component (API) within formulated samples were tracked using an image based particle characterisation system with an integrated Raman probe. In addition to the primary aim, the impact of excipient selection was also assessed. The study demonstrated the ability to track the size and shape of particles of a single component within a blended system. Process induced attrition can affect significant changes in the size and shape characteristics of the API particles. Whilst blending and cone milling were found to have minimal impact on the API properties, significant particle attrition was induced through transmission of the formulations through a powder feeding system. The impact of excipients within the formulated blends on API attrition propensity was observed to be low. The findings suggest that the propensity for particles to undergo process induced attrition should be taken into consideration when designing a manufacturing process and/or relating initial particle properties to the performance of intermediate or final dosage forms.

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.