Comparative analyses of flow and compaction properties of diverse mannitol and lactose grades

Specific surface area of mannitol rather than particle size dominant the dissolution rate of poorly water-soluble drug tablets: A study of binary mixture

The dissolution behavior of tablets, particularly those containing poorly water-soluble drugs, is a critical factor in determining their absorption and therapeutic efficacy. Traditionally, the particle size of excipients has been considered a key property affecting tablet dissolution. However, lurasidone hydrochloride (LH) tablets prepared by similar particle size mannitol, namely M200 (D90 = 209.68 ± 1.42 μm) and 160C (D90 = 195.38 ± 6.87 μm), exhibiting significant differences in their dissolution behavior. In order to find the fundamental influential factors of mannitol influencing the dissolution of LH tablets, the properties (particle size, water content, true density, bulk density, tapped density, specific surface area, circularity, surface free energy, mechanical properties and flowability) of five grades mannitol including M200 and 160C were investigated. Principal component analysis (PCA) was used to establish a relationship between mannitol properties and the dissolution behavior of LH. The results demonstrated that specific surface area (SSA) emerged as the key property influencing the dissolution of LH tablets. Moreover, our investigation based on the percolation theory provided further insights that the SSA of mannitol influences the probability of LH-LH bonding and LH infinite cluster formation, resulting in the different percolation threshold states, then led to different dissolution behaviors. Importantly, it is worth noting that these findings do not invalidate previous conclusions, as reducing particle size generally increases SSA, thereby affecting the percolation threshold and dissolution behavior of LH. Instead, this study provides a deeper understanding of the underlying role played by excipient SSA in the dissolution of drug tablets. This study provides valuable guidance for the development of novel excipients aimed at improving drug dissolution functionality.

Crystal defects creation in Mannitol@CaCl2 metal-organic framework by induced dehydration strategy for enhanced excipient mechanical properties

The mechanical properties of solid pharmaceutical excipients are important for assisting drug tables production, and they determine the quality of the drug tablets. The purpose of this study was to explore the potential and mechanism of crystal defect engineering to improve the mechanical properties of Mannitol@CaCl2 MOF, a pharmaceutical excipient with metal-organic framework (MOF) structure designed and prepared in our previous study. In this study, a simple and efficient "induced dehydration strategy" was proposed to prepare Mannitol@CaCl2 MOF with crystal defects (DEMOF). SEM, TEM, HRTEM, PXRD, FTIR, DSC-TGA, and N2 adsorption-desorption isotherm revealed the successful introduction of lattice vacancy and macrostructural defects while preserving MOF's skeleton structure. Tabletability profiles indicated that DEMOF presented much better mechanical properties than the original MOF at the powder level. On single crystal and atomic scales, nanoindentation and DFT calculations revealed that the defect structure increased plasticity, decreased brittleness, and improved compressibility, resulting in DEMOF tablets with much higher tensile strength that met the criteria for direct compression excipients. The achieved performance modification illustrated the capability of defect engineering to tune mechanical properties of MOFs, and the Mannitol@CaCl2 DEMOF exhibited great potential to serve as a new direct compression pharmaceutical excipient.

Sample Size Requirements of a Pharmaceutical Material Library: A Case in Predicting Direct Compression Tablet Tensile Strength by Latent Variable Modeling

The material library is an emerging, new data-driven approach for developing pharmaceutical process models. How many materials or samples should be involved in a particular application scenario is unclear, and the impact of sample size on process modeling is worth discussing. In this work, the direct compression process was taken as the research object, and the effects of different sample sizes of material libraries on partial least squares (PLS) modeling in the prediction of tablet tensile strength were investigated. A primary material library comprising 45 materials was built. Then, material subsets containing 5 × i (i = 1, 2, 3, …, 8) materials were sampled from the primary material library. Each subset underwent sampling 1000 times to analyze variations in model fitting performance. Both hierarchical sampling and random sampling were employed and compared, with hierarchical sampling implemented with the help of the tabletability classification index d. For each subset, modeling data were organized, incorporating 18 physical properties and tableting pressure as the independent variables and tablet tensile strength as the dependent variable. A series of chemometric indicators was used to assess model performance and find important materials for model training. It was found that the minimum R2 and RMSE values reached their maximum, and the corresponding values were kept almost unchanged when the sample sizes varied from 20 to 45. When the sample size was smaller than 15, the hierarchical sampling method was more reliable in avoiding low-quality few-shot PLS models than the random sampling method. Two important materials were identified as useful for building an initial material library. Overall, this work demonstrated that as the number of materials increased, the model's reliability improved. It also highlighted the potential for effective few-shot modeling on a small material library by controlling its information richness.

Effect of Material Properties and Variability of Mannitol on Tablet Formulation Development

PURPOSE

Using a high level of mannitol as a diluent in oral formulations can potentially result in tablet defects (e.g., chipping, cracking) during compression. This work aims to scrutinize the linkage between the mechanical properties and material attributes of mannitol and also uncover how variations between vendors and lots can lead to significant changes in the compaction performance of tablet formulations containing mannitol.

METHODS

The mechanical properties (Poisson's ratio, fracture energy) and mechanical performance (ejection force, pressure transmission ratio, residual radial die-wall stress, and tensile strength) of mannitol compacts were assessed on a compaction simulator for four lots of mannitol from two different vendors. The variation of material attributes of each lot, including particle size distribution (PSD), crystal form, primary crystal size and morphology, specific surface area (SSA), powder flow, and moisture absorption were investigated.

RESULTS

The variability of material attributes in mannitol lots, especially primary crystal size and SSA, can result in significant changes in mechanical properties and mechanical performance such as ejection force and residual radial die-wall stresses, which potentially led to chipping during compression.

CONCLUSION

The study elucidated the linkage between fundamental material attributes and mechanical properties of mannitol, highlighting their impact on tablet defects and compaction performance in compression. A comprehensive understanding of the variability in mannitol properties between vendors and lots is crucial for successful formulation development, particularly when high percentages of mannitol are included as a brittle excipient.

Comparative Study of Selected Excipients' Influence on Carvedilol Release from Hypromellose Matrix Tablets

Solid dosage forms based on hypromellose (HPMC) with prolonged/extended drug release are very important from the research and industrial viewpoint. In the present research, the influence of selected excipients on carvedilol release performance from HPMC-based matrix tablets was studied. A comprehensive group of selected excipients was used within the same experimental setup, including different grades of excipients. Compression mixtures were directly compressed using constant compression speed and main compression force. LOESS modelling was used for a detailed comparison of carvedilol release profiles via estimating burst release, lag time, and times at which a certain % of carvedilol was released from the tablets. The overall similarity between obtained carvedilol release profiles was estimated using the bootstrapped similarity factor (f₂). In the group of water-soluble carvedilol release modifying excipients, which produced relatively fast carvedilol release profiles, POLYOXᵀᴹ WSR N-80 and Polyglykol^® 8000 P demonstrated the best carvedilol release control, and in the group of water-insoluble carvedilol release modifying excipients, which produced relatively slow carvedilol release profiles, AVICEL^® PH-102 and AVICEL^® PH-200 performed best.

Assessment of Tribo-charging and Continuous Feeding Performance of Direct Compression Grades of Isomalt and Mannitol Powders

Tribo-charging is often a root cause of mass flow deviations and powder adhesion during continuous feeding. Thus, it may critically impact product quality. In this study, we characterized the volumetric (split- and pre-blend) feeding behavior and process-induced charge of two direct compression grades of polyols, galenIQ™ 721 (G721) for isomalt and PEARLITOL^® 200SD (P200SD) for mannitol, under different processing conditions. The feeding mass flow range and variability, hopper end fill level, and powder adhesion were profiled. The feeding-induced tribo-charging was measured using a Faraday cup. Both materials were comprehensively characterized for relevant powder properties, and their tribo-charging was investigated for its dependence on particle size and relative humidity. During split-feeding experiments, G721 showed a comparable feeding performance to P200SD with lower tribo-charging and adhesion to the screw outlet of the feeder. Depending on the processing condition, the charge density of G721 ranged from -0.01 up to -0.39 nC/g, and for P200SD from -3.19 up to -5.99 nC/g. Rather than differences in the particle size distribution of the two materials, their distinct surface and structural characteristics were found as the main factors affecting their tribo-charging. The good feeding performance of both polyol grades was also maintained during pre-blend feeding, where reduced tribo-charging and adhesion propensity was observed for P200SD (decreasing from -5.27 to -0.17 nC/g under the same feeding settings). Here, it is proposed that the mitigation of tribo-charging occurs due to a particle size-driven mechanism.

Classification of scanning electron microscope images of pharmaceutical excipients using deep convolutional neural networks with transfer learning

Convolutional Neural Networks (CNNs) are image analysis techniques that have been applied to image classification in various fields. In this study, we applied a CNN to classify scanning electron microscopy (SEM) images of pharmaceutical raw material powders to determine if a CNN can evaluate particle morphology. We tested 10 pharmaceutical excipients with widely different particle morphologies. SEM images for each excipient were acquired and divided into training, validation, and test sets. Classification models were constructed by applying transfer learning to pretrained CNN models such as VGG16 and ResNet50. The results of a 5-fold cross-validation showed that the classification accuracy of the CNN model was sufficiently high using either pretrained model and that the type of excipient could be classified with high accuracy. The results suggest that the CNN model can detect differences in particle morphology, such as particle size, shape, and surface condition. By applying Grad-CAM to the constructed CNN model, we succeeded in finding particularly important regions in the particle image of the excipients. CNNs have been found to have the potential to be applied to the identification and characterization of raw material powders for pharmaceutical development.

A Multivariate Formulation and Process Development Platform for Direct Compression

The efficient development of robust tableting processes is challenging due to the lack of mechanistic understanding on the impact of raw material properties and process parameters on tablet quality. The experimental determination of the effect of process and formulation parameters on tablet properties and subsequent optimization is labor-intensive, expensive and time-consuming. The combined use of an extensive raw material property database, process simulation tools and multivariate modeling allows more efficient and more optimized development of the direct compression (DC) process. In this study, key material attributes and in-process mechanical properties with a potential effect on tablet processability and tablet properties were identified. In a first step, an extensive characterization of 55 raw materials (over 100 material descriptors) (Van Snick et al., 2018) and 26 formulation blends (31 material descriptors) (Dhondt et al., 2022) was performed. These blends were subsequently compacted on a compaction simulator under multiple process conditions through a design of experiments (DoE) approach. A T-shaped partial least squares (T-PLS) model was established which correlates tablet quality attributes with process settings, raw material properties and blend ratios. During future development of the DC formulation and process for a new active pharmaceutical ingredient (API), this model can then be used to provide a preliminary formulation and compaction process settings as starting point to be further optimized during development trials based on well-defined raw material characteristics and compaction tests. This study hence contributes to a better understanding on the impact of raw material properties and process settings on a DC process and final properties of the produced tablets; and provides a platform allowing a more efficient and more optimized development of a robust tableting process.

Tablet formulation development focusing on the functional behaviour of water uptake and swelling

The functional behaviour of tablets is strongly influenced by their manufacturing process and the choice of excipients. Water uptake and swelling are prerequisites for tablet disintegration, dispersion and hence active pharmaceutical ingredient (API) dissolution. High proportions of polymeric excipients in tablets, which are typically used as API carriers in amorphous solid dispersions (ASDs), may be challenging due to the formation of a gelling polymer network (GPN). In this study, systematic investigations into the formulation development of tablets containing polymeric and other excipients are performed by water uptake and swelling analysis. The impact of tablet composition and porosity as well as pH of the test medium are investigated. The pH affects the analysis results for Eudragit L100-55 and Eudragit EPO. HPMC and Kollidon VA64 inhibit water uptake and swelling of tablets due to the formation of a GPN. High tablet porosity, coarse particle size of the polymer and the addition of fillers and disintegrants can reduce the negative impact of a GPN on tablet performance. The application of lubricants slows down the analysed processes. Water uptake and swelling data are fitted to an empirical model obtaining four characteristic parameters to facilitate the simple quantitative assessment of varying tablet formulations and structural properties.

Continuous Twin Screw Granulation: A Review of Recent Progress and Opportunities in Formulation and Equipment Design

Continuous twin screw wet granulation is one of the key continuous manufacturing technologies that have gained significant interest in the pharmaceutical industry as well as in academia over the last ten years. Given its considerable advantages compared to wet granulation techniques operated in batch mode such as high shear granulation and fluid bed granulation, several equipment manufacturers have designed their own manufacturing setup. This has led to a steep increase in the research output in this field. However, most studies still focused on a single (often placebo) formulation, hence making it difficult to assess the general validity of the obtained results. Therefore, current review provides an overview of recent progress in the field of continuous twin screw wet granulation, with special focus on the importance of the formulation aspect and raw material properties. It gives practical guidance for novel and more experienced users of this technique and highlights some of the unmet needs that require further research.

Preparation of Solifenacin Succinate Functional Particles Embedded in a Gelling-Swelling Layer (PEGS) and Their Formulation in Orally Disintegrating Tablets

The purpose of this research was firstly to prepare solifenacin succinate functional particles embedded in a gelling-swelling layer (PEGS) so as to achieve both taste-masking of the unpleasant taste of the drug and rapid drug elution, and secondly to incorporate these PEGS into orally disintegrating tablets (ODTs). In in vitro dissolution tests, initial drug release from the prepared PEGS could be suppressed to less than 1% after 2 min and increased to more than 85% after 30 min by adjusting the composition of the PEGS, in particular the thickness of the outer water-penetration control layer which contains a water-insoluble polymer. For the preparation of ODTs containing PEGS, a semi-direct compression method was adopted in order to prevent damage to the PEGS by processes such as granulation or compaction. The use of a fibre-shaped microcrystalline cellulose with poor fluidity improved the content uniformity of the ODTs, as the crystal fibres became entangled with the PEGS and other additives. The use of spherical mannitol with a hollow structure produced by spray drying imparted relatively high hardness and rapid disintegration properties to the final ODTs containing PEGS, which were tableted using a low compression force. There was no significant difference in the drug-release profiles of the optimally formulated ODTs containing PEGS tableted at different compression forces. The ODTs containing PEGS maintained a drug-release lag time sufficient for taste-masking of solifenacin succinate.

Powder flow from an intermediate bulk container - Discharge predictions and experimental evaluation

Powders are usually dispensed, blended, and transferred between different manufacturing steps in so-called Intermediate Bulk Containers (IBCs), and discharge from an IBC plays a critical role in the ability to manufacture high-quality tablets. To better understand IBC discharge, the flow behavior of selected excipients was comprehensively characterized using a number of techniques including the Hausner ratio/Carr's index, Erweka flow test, FlowPro flow test, shear test and wall friction test as well as FT4 powder rheometer experiments. Jenike's hopper design methodology was then used to predict the minimum non-arching outlet diameter and the mode of flow. Furthermore, the discharge rate from an IBC was predicted using a simple model that takes into account gravity and aerodynamic drag. The predictions were experimentally verified by measuring the discharge rate from a 20 L IBC using five commonly-used excipients. The small-scale Erweka flow test provided the best prediction of the full-scale IBC discharge experiment. Furthermore, a simple model that relied only on the particle size of the material and the diameter of the discharge opening was found to predict the IBC discharge rate remarkably well.

An insight into predictive parameters of tablet capping by machine learning and multivariate tools

Capping is the frequently observed mechanical defect in tablets arising from the sub-optimal selection of the formulation composition and their robustness of response toward process parameters. Hence, overcoming capping propensity based on the understanding of suitable process and material parameters is of utmost importance to expedite drug product development. In the present work, 26 diverse formulations were characterized at commercial tableting condition to identify key tablet properties influencing capping propensity, and a predictive model based on threshold properties was established using machine learning and multivariate tools. It was found that both the compaction parameters (i.e., compaction pressure, radial stress transmission characteristics, and Poisson's ratio), and the material properties, (i.e., brittleness, yield strength, particle bonding strength and elastic recovery) strongly dictate the capping propensity of a tablet. In addition, ratio of elastic modulus in the orthogonal direction in a tablet and its variation with porosity were notable quantitative metrics of capping occurrence.

Direct compression tablet formulation of celecoxib enabled with a pharmaceutical solvate

Celecoxib, an anti-inflammatory drug for pain and arthritis, is currently only available in capsule form. To reduce the onset time for a faster action and to lower the manufacturing cost, the tablet dosage form is more preferred. However, the commercial celecoxib (Form III) is not suitable for direct compression (DC) tablet manufacture due to poor flow, low bulk density, and tablet lamination. In this work, we overcome these challenges using a pharmaceutically acceptable dimethyl sulfoxide (DMSO) solvate of celecoxib. Aided with the DMSO solvate, an acceptable DC tablet formulation was successfully developed to manufacture tablets containing 200 mg celecoxib, with satisfactory manufacturability, disintegration, and in vitro dissolution performance.

Understanding flow properties of mannitol powder at a range of temperature and humidity

Inadequate flowability of powders in industries during handling can cause many problems. For example, lack of flow from hoppers, poor tablet weight consistency, and low production rate in tableting. Many factors are known to commonly affect flow properties of powders, such as temperature, humidity and conditioning duration. In this paper, flow properties of a mannitol powder, which was conditioned between 24 and 72 h at various high relative humidities and temperature, were measured using a shear tester. A statistical model was developed to investigate the relative importance of these variables on the mannitol flow properties. The developed model showed all independent variables are significant in estimating bulk cohesion. Two separate approaches were used to evaluate inter-particle forces in the bulk, and how these changed with environmental conditions. First, inter-particle forces were inferred from the measured bulk properties using the Rumpf model approach. Secondly, inter-particle forces were predicted based on a model of moisture present on the particle surface using a combination of Kelvin model with the Laplace-Young (KLY) equation. The second approach also involved a new method to measure surface energy of mannitol powder based on measurements using Finite Dilution Inverse Gas Chromatography (FD-IGC). The surface energies of the mannitol powder were measured at high temperature (35 °C) and at different range of relative humidities. In spite of the fundamentally different approaches to the two ways of inferring inter-particles forces, these forces came out within less than 1.5:1 in magnitude. The Rumpf approach from bulk behaviour data obviously reflected the measured change in behaviour with humidity in particular, but this was not predicted from the KLY approach, however the likely reasons for this are postulated and recommendations for improvement are made.

Multiparticulate oral formulations as a viable strategy for precise drug dosing in pediatrics: Propranolol case study

The development of solid dosage forms that are both convenient for administration and allow precise drug dosing for pediatric patients is one of the great challenges in contemporary pharmaceutical technology. The presented study has utilized propranolol hydrochloride, as one of the most frequently prescribed drugs that require manipulation of the conventional dosage forms to be administered to children. Multiparticulate oral formulations, powderand granulefilled capsules, as well as mini tablets, were prepared and characterized in terms of their mass and content uniformity and compared to conventional marketed tablets split into halves and quarters. The obtained results have demonstrated the superiority of the multiparticulate formulations, in terms of their average mass and drug content uniformity. It has also been demonstrated that, due to improved flowability, granule-filled capsules are more conveniently compounded and provide higher content uniformity compared to powder-filled capsules. The presented compounding method could be easily employed in community pharmacy settings. Mini tablets with high and uniform content of propranolol hydrochloride have been successfully prepared, thereby presenting a viable strategy for efficient drug dose adjustment.

Investigation into powder tribo-charging of pharmaceuticals. Part I: Process-induced charge via twin-screw feeding

Powder feeding is a crucial unit operation in continuous manufacturing (CM) of pharmaceutical products. Twin-screw feeders are typically employed to ensure the accurate mass flow of pharmaceutical materials throughout the production process. Here, contact and separation of particles can give rise to electrostatic charges, affecting feeder performance and final product quality. The knowledge of the material charging tendency would therefore be beneficial for both formulation and process design. At the early stage of product development, only a limited amount of material is available and the propensity of the powders to charge needs to be assessed on lab test equipment, which not necessarily represent the material state during processing. In this study, the tribo-charging behaviour of a set of common pharmaceutical materials (i.e., microcrystalline cellulose, D-mannitol, paracetamol and magnesium stearate) was experimentally evaluated. To this end, powder materials were let to flow over the stainless-steel pipes of the GranuCharge™ instrument. The resulting charge was compared to the one acquired during twin-screw feeding. In both cases, paracetamol exhibited the highest charging tendency followed by D-mannitol and microcrystalline cellulose and last by magnesium stearate. A good correlation was found for charge values obtained for both methods, despite the different tribo-charging mechanisms involved in the two set-ups. However, these differences in experimental set-ups led to diverse magnitudes and, in one case, polarity of charge. Additionally, an extensive material characterization was performed on the selected powders and results were statistically analyzed to identify critical material attributes (CMAs) affecting powder tribo-charging. A strong correlation was obtained between the measured charge and inter-particle friction. This indicated the latter as one of the most influencing material characteristic impacting the powder tribo-charging phenomenon of the selected materials.

Preparation and optimization of multi-functional directly compressible excipient: an integrated approach of principal component analysis and design of experiments

Developing a new excipient and obtaining its market approval is an expensive, time-consuming, and complex process. The application of a multivariate analytical approach - principal component analysis (PCA) - in combination with the design of experiments (DoE) approach can make the process of developing co-processed excipient cost-effective and rapid. The present investigation was aimed to demonstrate the applicability of the DoE approach and PCA in developing a co-processed excipient by using the spray drying technique. The preliminary studies suggested a significant effect of inlet air temperature (X ₁) and polymer ratio [chitosan chlorhydrate (CC): mannitol - X ₂) on critical product characteristics so they were selected as independent variables in 3² full factorial design. The result of regression analysis suggested a significant effect of both independent variables on all response variables. The PCA of practically obtained value suggested a strong effect of all the selected response variables on the model. The prepared co-processed excipient had better tableting properties compared to the physical mixture of excipients and was able to accommodate more than 80% drug without compromising the flow property and compressibility. The present investigation successfully proved the applicability PCA and DoE approach as an effective and rapid tool for optimizing process parameters and formulation composition for preparing a directly compressible co-processed excipient.

Evaluation of Weight Variation in Mini-Tablets Manufactured by a Multiple-Tip Tool

Recently, owing to their pharmaceutical and clinical utility, mini-tablets have been well studied by researchers. Mini-tablets are usually manufactured by compression molding using a multiple-tip tool in a rotary tableting machine. Owing to their special structure, ensuring uniformity is a very important challenge in the manufacturability of mini-tablets using the multiple-tip tool. In this study, we aimed to evaluate the weight variation in mini-tablets produced by a multiple-tip tool, which is considered to be the root cause affecting the uniformity, and to investigate the physical properties of drug granules and tableting conditions in a rotary tableting machine that could reduce this weight variation. In addition, the relationship between these factors and response was visualized using response surface analysis. It was shown that the weight variation in mini-tablets produced by a multiple-tip tool was reduced when using a forced feeder compared with an open feeder. Furthermore, in the case of an open feeder, the optimal range of the average particle size diameter of drug granules and the rotational speed of the rotating disc in the rotary tableting machine were determined from response surface analysis. It was suggested that it is possible to reduce the weight variation in the mini-tablets by selecting drug granules with an average particle size diameter of 100-150 µm and using tableting conditions with a rotational speed of 40-60 rpm. This study elucidated the factors that affect uniformity and determined their optimal range for the manufacture of mini-tablets.

Effect of Different Direct Compaction Grades of Mannitol on the Storage Stability of Tablet Properties Investigated Using a Kohonen Self-Organizing Map and Elastic Net Regression Model

This study tested 15 direct compaction grades to identify the contribution of different grades of mannitol to the storage stability of the resulting tablets. After preparing the model tablets with different values of hardness, they were stored at 25 °C, 75% relative humidity for 1 week. Then, measurement of the tablet properties was conducted on both pre- and post-storage tablets. The tablet properties were tensile strength (TS), friability, and disintegration time (DT). The experimental data were analyzed using a Kohonen self-organizing map (SOM). The SOM analysis successfully classified the test grades into three distinct clusters having different changes in the behavior of the tablet properties accompanying storage. Cluster 1 showed an obvious rise in DT induced by storage, while cluster 3 showed a substantial change in mechanical strength of the tablet including a reduction in the TS and a rise in friability. Furthermore, the data were analyzed using an Elastic net regression technique to investigate the general relationships between the powder properties of mannitol and the change behavior of the tablet properties. Consequently, we succeeded in identifying the crucial powder properties for the storage stability of the resulting tablets. This study provides advanced technical knowledge to characterize the effect of different direct compaction grades of mannitol on the storage stability of tablet properties.

Twin-screw granulation and high-shear granulation: The influence of mannitol grade on granule and tablet properties

Granule structure has a key influence on tablet critical quality attributes. The ability to control this structure through excipient choice is an important part of formulation development. Mannitol is a popular diluent and the choice of input grade has been shown to impact granule properties. Allopurinol formulations containing two grades of mannitol (Pearlitol 160C and 200SD) were prepared by wet-granulation (twin-screw and high-shear) at different liquid/solid ratios (0.3 and 0.6 g/g). The particle and bulk properties were characterised by a range of techniques and linked to flow performance and tablet tensile strength during compression on a rotary tablet press. During granulation, 200SD underwent a polymorphic transition from a mixture of α and β to predominantly β. This transition was accompanied by a morphology change. Mannitol needles were formed, giving more porous granules with a higher specific surface area, which led to poorer flow properties but higher tablet tensile strength. This study concludes that understanding the effect of mannitol grade is a crucial part of formulation selection.

Polymer-Assisted Aripiprazole-Adipic Acid Cocrystals Produced by Hot Melt Extrusion Techniques

Pharmaceutical cocrystals are a promising strategy to increase the solubility and dissolution rate of poorly soluble drugs. However, their manufacturing process requires a large quantity of solvents. The present study aimed to produce cocrystals by a solvent-free hot melt extrusion (HME) method to improve their solubility and dissolution rate. Aripiprazole (ARP) and adipic acid (ADP) were used as a weakly basic drug and acidic coformer, respectively. The processability of a plain ARP-ADP physical mixture (PM) compared with a PM with 5% Soluplus® (SOL) was investigated. Incorporating 5% SOL into the ARP-ADP blend reduced the processing torque and improved processability. The effects of temperature and screw speed on the formation of cocrystals were studied, and cocrystals were characterized by differential scanning calorimetry (DSC), fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, powder X-ray diffraction (PXRD), scanning electron microscopy, and hot-stage microscopy. FTIR spectra revealed noncovalent interaction between ARP and ADP, which was confirmed by NMR spectra. Similarly, PXRD data exhibited characteristic peaks confirming the formation of new crystalline material. Further, the results indicated that cocrystals demonstrated higher dissolution rates and improved compressibility, as well as enhanced flow characteristics compared with pure ARP, suggesting its suitability in the development of solid dosage forms.

Characterization of Powder- and Tablet Properties of Different Direct Compaction Grades of Mannitol Using a Kohonen Self-organizing Map and a Lasso Regression Model

The purpose of this study was to accumulate enhanced technical knowledge about the powder properties of direct compaction grades of mannitol that could lead to new tablet formulations. Fifteen different commercial direct compaction grades of mannitol were tested. Ten different powder properties representing flowability, particle size, specific surface area and manufacturing properties were measured. In addition, model tablets of each mannitol grade were prepared, and their disintegration time, friability, and tensile strength were measured. The data were analyzed by principle component analysis and a Kohonen self-organizing map to find correlations between powder properties. Self-organizing map clustering successfully classified the test grades into 5 distinct clusters having different powder properties. Each cluster was well characterized by statistical profiling. Subsequently, the contribution of the powder properties to the tablet properties was investigated by a least absolute shrinkage- and selection operator (Lasso) regression model. Mannitol grades with a larger particle size (D90) were prone to produce tablets with longer disintegration time, while a larger specific surface area of the particles was positively associated with tablets with higher mechanical strength. Our findings provide valuable information for the design of tablet formulations.

A systematic evaluation of poloxamers as tablet lubricants

Lubricants are important for both preserving the tooling of high-speed tablet presses and attaining quality tablets. Magnesium stearate (MgSt) is most commonly used due to its superior lubrication efficiency; however, it can lead to negative effects on tabletability and dissolution. In this study, we have systematically evaluated two poloxamers, P188 and P407, for their suitability as alternative tablet lubricants. For two excipients with different mechanical properties, i.e., microcrystalline cellulose and lactose, both poloxamers exhibit acceptable lubrication efficiency without negatively impacting tabletability. Compared to 1% MgSt, the performance of 2% of both poloxamers in an experimental tablet formulation of ritonavir led to better lubrication, higher tabletability, and enhanced in vitro drug release. Thus, the use of P188 and P407 as alternative tablet lubricants deserves further evaluations.

Psyllium (Plantago Ovata Forsk) Husk Powder as a Natural Superdisintegrant for Orodispersible Formulations: A Study on Meloxicam Tablets

(1) Background: In this work, we investigated the application of a natural superdisintegrant, psyllium (Plantago ovata Forsk) husk powder, for the manufacture of orodispersible meloxicam tablets. Meloxicam was chosen as a model compound for the study. (2) Methods: The tablets were prepared using different concentrations of psyllium husk by direct compression. Bulk density, tapped density, hardness, friability, in vitro disintegration, and dissolution time tests were used to assess the quality of the formulations. (3) Results: Psyllium husk powder significantly increased the dissolution rate of meloxicam. The formulation containing 16 mg of psyllium husk powder showed the lowest wetting time, the highest water absorption ratio, and the lowest disintegration time compared to the control and to the other formulations. These effects may be attributed to the rapid uptake of water due to the vigorous swelling ability of psyllium husk powder. (4) Conclusions: The powder could be recommended as an effective natural superdisintegrant for orodispersible formulations.

Exploring the chemical space for freeze-drying excipients

Commonly, a limited number of generally accepted bulking agents and lyoprotectants are used for freeze-drying; predominantly mannitol, glycine, sucrose and trehalose. The purpose of this study was to combine a theoretical approach using molecular descriptors with a large scale experimental screening to evaluate the suitability of a broad range of excipients for freeze-drying. A large selection of sugars, polyols and amino acids was characterized by modulated differential scanning calorimetry (mDSC) and X-ray powder diffraction (XRPD) after well-plate based freeze-drying. The calculated molecular descriptors were investigated with both hierarchical cluster analysis and principal component analysis. A clear clustering of the excipients according to the size-related and weight-related descriptors was observed; however other relevant descriptors could also be identified. From a practical perspective, a trend was observed with regard to a higher likelihood for amorphisation and a higher glass transition temperature of the maximally freeze-concentrated solution with increasing molecular size. A translation of the molecular descriptors on pharmaceutical performance was more successful for lyoprotectants than for bulking agents. Additionally, in the course of the experimental screening, several new potential bulking agents and lyoprotectants were identified.

Tableting performance of various mannitol and lactose grades assessed by compaction simulation and chemometrical analysis

Mannitol and lactose are commonly used fillers in pharmaceutical tablets, available in several commercial grades that are produced using different manufacturing processes. These grades significantly differ in particulate and powder properties that impact tablet manufacturability. Choice of sub-optimum type or grade of excipient in tablet formulation can lead to manufacturing problems and difficulties, which are magnified during a continuous manufacturing process. Previous characterization of tableting performance of these materials was limited in scope and under conditions not always realistic to the commercial production of tablets. This work seeks to comprehensively characterize the compaction properties of 11 mannitol and 5 lactose grades using a compaction simulator at both slow and fast tableting speeds. These include tabletability, compressibility, tablet brittleness, die-wall stress transmission, and strain rate sensitivity. A chemometrical analysis of data, using the partial least square technique, was performed to construct a model to provide accurate prediction of tablet tensile strength for mannitol grades. Such knowledge facilitates the selection of suitable tablet filler to attain high quality tablet products.

Proportionality between powder cohesion and unconfined yield strength from shear cell testing

From an analysis of the geometry of the yield locus and the Mohr's circle for determining unconfined yield strength (f c) in shear cell testing, it has been shown that powder cohesion is proportional to f c, where the proportionality constant is a function of angle of linearized yield locus, (1-sinθ)/(2cosθ). While both parameters are routinely included in shear cell data, only one parameter is needed to characterize flow properties of a new powder.

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.

Twin Screw Granulation: Effects of Properties of Primary Powders

Lactose and mannitol are some of the most commonly used powders in the pharmaceutical industry. The limited research published so far highlights the effects of process and formulation parameters on the properties of the granules and the tablets produced using these two types of powders separately. However, the comparison of the performance of these two types of powders during twin screw wet granulation has received no attention. The present research is focused on understanding the granulation mechanism of different grades of two pharmaceutical powders with varying properties (i.e., primary particle size, structure, and compressibility). Three grades each of lactose and mannitol were granulated at varying liquid to solid ratios (L/S) and screw speed. It was noticed that primary powder morphology plays an important role in determining the granule size and structure, and tablet tensile strength. It was indicated that the processed powders such as spray-dried and granulated lactose and mannitol can be used in formulation for wet granulation where flowability of active pharmaceutical ingredient (API) is poor.