Characterisation of pore structures of pharmaceutical tablets: A review

Does tablet shape and height influence survival of fluidized bed-granulated living microorganisms during compaction?

The provision of effective probiotic formulations requires gentle processing to maintain the viability of the probiotic microorganisms, which is essential for their health-promoting effects. The drying of microorganisms by fluidized bed spray granulation and subsequent processing of the granules into tablets has proven to be a promising process route in previous studies of the same authors. In these, the influence of various factors was considered using cylindrical tablets with a diameter of 11.28 mm and a mass of 450 mg. These flat tablets are unpleasant to ingest and other tablet geometries should be considered for administration of probiotics but to date, no studies exist on the influence of geometric factors of the tableting tool and of the tablets on the survival of microorganisms. To address this aspect, the survival of Saccharomyces cerevisiae during the production of flat, round tablets with different tablet masses and thus heights as well as differently shaped convex tablets is determined and related to the physical-mechanical tablet properties to derive process-structure-property relationships. It turned out that higher tablet heights were advantageous regarding microbial survival and mechanical strength which is attributed to a lower elastic recovery. However, the use of differently shaped tools had a smaller influence on microbiological and mechanical tablet properties since the global tablet porosity was hardly affected.

Impact of pharmaceutical tablet properties on optical porosimetry performance

The porosity of a pharmaceutical tablet influences liquid transport, disintegration and dissolution, rendering its monitoring and control crucial for quality by design. Optical porosimetry, a non-destructive process analytical technology (PAT), combines gas in scattering media absorption spectroscopy (GASMAS), photon time-of-flight spectroscopy (PToFS), tablet thickness measurement and tablet solid refractive index. This article presents a short tutorial on optical porosimetry theory and a performance study of optical porosimetry on pharmaceutical tablets via design of experiments. The investigated tablets share the same formulation, solid refractive index and diameter but differ in porosity (∼0.05 and 0.25) and thickness (1, 3 and 5mm). Critical user-controllable factors impacting the measurement accuracy and precision of the investigated tablets were identified. These are the manufactured tablet thickness, porosity, the user-estimated solid refractive index, and the number of optical porosimetry measurements in decreasing order of significance. A comparison between tablet porosity measured by optical porosimetry and by nominal measurements revealed that optical porosimetry tends to overestimate the porosity of the investigated tablets, particularly at low porosities, and has greater variability. While optical porosimetry poses advantages as a non-destructive and rapid PAT for real-time release testing, users need to be aware of the appropriate range of tablet thickness, porosity and the solid refractive index estimate.

The role of porosity in polyester microparticles for drug delivery

Polymer microparticles are a cornerstone in the field of injectable sustained delivery systems: They allow the entrapment of various types of hydrophobic or hydrophilic drugs including biopharmaceuticals. Microparticles can be prepared from the material of choice and tailored to specific target sizes. Importantly, they can retain the drug at the local administration site to achieve a sustained drug release for long-term therapeutic effects. This review focuses on the role of porosity of microparticles as a tremendously important property. Principles to prepare porous carriers via different techniques and additives are discussed, emphasizing that porosity is not a static property but can be dynamic, e.g., for particles from polylactide or poly(lactide-co-glycolide). Considering the contribution of porosity in the overall assessment of drug carrier systems, as well as their manipulation/alteration post-production such as by pore closing, will enlarge the understanding of polymer microparticles as an important class of modern pharmaceutical dosage forms.

Spiked Systems for Colonic Drug Delivery: Architectural Opportunities and Quality Assurance of Selective Laser Sintering

Additive manufacturing has been a breakthrough therapy for the pharmaceutical industry raising opportunities for long-quested properties, such as controlled drug-delivery. The aim of this study was to explore the geometrical capabilities of selective laser sintering (SLS) by creating spiked (tapered-edged) drug-loaded specimens for administration in colon. Poly(vinyl alcohol) (PVA) was used as the binding material and loperamide hydrochloride was incorporated as the active ingredient. Printing was feasible without the addition of a sintering agent or other additives. Innovative printing protocols were developed to help improve the quality of the obtained products. Intentional vibrations were applied on the powder bed through rapid movements of the printing platform in order to facilitate rigidity and consistency of the printed objects. The drug-loaded products had physicochemical properties that met the pharmacopoeia standards and exhibited good biocompatibility. The behavior of spiked balls (spherical objects with prominent spikes) and their retention time in the colon was assessed using a custom ex vivo intestinal setup. The spiked balls showed favorable mucoadhesive properties over the unspiked ones. No movement on the tissue was recorded for the spiked balls, and specimens with more spikes exhibited longer retention times and potentially, enhanced bioavailability. Our results suggest that SLS 3D printing is a versatile technology that holds the potential to revolutionize drug delivery systems by enabling the creation of complex geometries and medications with tunable properties.

Understanding the complexity of near-infrared quantification of highly porous patient-tailored drug products by utilizing chemometrics and stimulated Raman imaging

Additively manufactured drug products, typically produced using small-scale, on-demand batch mode, require rapid and non-destructive quantification methods. A tunable modular design (TMD) approach combining porous polymeric freeze-dried modules and an additive manufacturing method, inkjet printing, was proposed in an earlier study to fabricate accurate and patient-tailored doses of an antidepressant citalopram hydrobromide. This approach addresses the unmet medical needs associated with antidepressant tapering. Non-destructive quantification of printed porous structures is challenging due to the presence of residual solvents and frequent fluctuation of the material density. These shortcomings were mitigated by utilizing a spinning near-infrared spectroscopy (NIRS) measurement setup and a post-print drying step. A machine learning algorithm (ML), specifically support vector regression, was implemented to lessen potential non-linearities caused by the complex structure of TMD drug products. The non-linear support vector regression models performed better than linear partial least squares (PLS) models when modeling the entire sample set (prediction error improved by 19 %). By dividing the TMD samples into subtypes and creating individual models for each subtype improved model performance: linear PLS models performed better or equally to non-linear models. It was hypothesized that this outcome was due to the structural differences between different TMD sample subtypes that was later confirmed by stimulated Raman scattering (SRS) microscopy. It was demonstrated that for complex porous drug products ML algorithms can improve NIRS model performance when a single universal robust model is preferred, and SRS is a powerful tool to explain the challenges that printing onto porous drug products can introduce to the NIRS quantification.

"3D channel maze" to control drug release from multiple unit tablets

Diffusion is defined as general mechanism for drug release from advanced delivery systems, yet dynamic structure of dosage form intrinsically plays an unknown role. The synchrotron radiation X-ray micro-computed tomography (SR-μCT) three-dimensional (3D) imaging and in-depth analysis of 3D structures were applied to readily differentiate materials and accurately capture internal structure changes of multiple unit pellet system (MUPS) and the constituent pellets, visualizing internal 3D structure of a MUPS of theophylline tablets for their 3 levels hierarchy structures: pellets with rapid drug release characteristics, a protective cushion layer and a matrix layer. Drug release pathways were extracted from SR-μCT images and a 3D maze network was constructed using pore network analysis to quantify the internal structural evolution during drug release. In the initial stage of dissolution about 1 h, theophylline release from the MUPS is dominated by diffusion from the matrix layer, whilst the second phase of 23 h constant release kinetics is dominated by a 3D channel maze architecture with outlets/channels connecting pellets in the remains of the MUPS, which forms the 3D channel maze as pore networks. The random walking of the dissolved theophylline molecules retarded by the tortuous 3D channel maze which led to the observed controlled release profile as a whole. Based on SR-μCT investigations and 3D structure analysis, a new approach to control drug release via a 3D channel maze structure was discovered.

Quantitative Structural and Compositional Elucidation of Real-World Pharmaceutical Tablet Using Large Field-of-View, Correlative Microscopy-Tomography Techniques and AI-Enabled Image Analysis

PURPOSE

The purpose of this study is to present a correlative microscopy-tomography approach in conjunction with machine learning-based image segmentation techniques, with the goal of enabling quantitative structural and compositional elucidation of real-world pharmaceutical tablets.

METHODS

Specifically, the approach involves three sequential steps: 1) user-oriented tablet constituent identification and characterization using correlative mosaic field-of-view SEM and energy dispersive X-ray spectroscopy techniques, 2) phase contrast synchrotron X-ray micro-computed tomography (SyncCT) characterization of a large, representative volume of the tablet, and 3) constituent segmentation and quantification of the imaging data through user-guided, iterative supervised machine learning and deep learning.

RESULTS

This approach was implemented on a real-world tablet containing 15% API and multiple common excipients. A representative volumetric tablet image was obtained using SyncCT at a 0.36-µm resolution, from which constituent particles and pores were fully segmented and quantified. As validation, the derived tablet formulation composition and porosity agreed with the experimental values, despite the micrometer-scale particle and pore sizes. The approach also revealed the formation of ordered mixture inside the tablet. Notably, the image-derived size distributions of both the agglomerated microcrystalline cellulose and its primary particulate units matched the laser diffraction-based measurements of the as-is material. Key pore attributes including the pore size distribution, spatial anisotropy, and pore interconnectivity were also qualified.

CONCLUSION

Overall, this study demonstrated that the correlative microscopy-tomography approach, by leveraging phase contrast SyncCT and AI-based image analysis, can deliver new, practically-useful structural and compositional information and facilitate more efficient formulation and process development of tablets.

In-line porosity and hardness monitoring of tablets by means of optical coherence tomography

In-line monitoring of critical quality attributes (CQAs) during a tableting process is an essential step toward a real-time release strategy. Such CQAs can be the tablet mass, the API content, dissolution, hardness and tensile strength. Since dissolution testing is laborious and time-consuming and cannot be performed in-line, it is desirable to replace dissolution testing with predictive models based on other CQAs that affect the dissolution characteristics, such as the tablet porosity and hardness. Traditionally, porosity is determined offline via gas adsorption methods or other techniques, such as Terahertz spectroscopy or gas in scattering media absorption spectroscopy. Tablet hardness is typically established using a hardness tester. While these destructive tests can readily be performed at-line, they have limited applicability in in-line settings for a high-percentage inspection. Optical coherence tomography (OCT) has recently been proposed as a possible tool for determining quality attributes. This work describes the first application of OCT for the prediction of tablet porosity and hardness. OCT measurements of tablets produced in a ConsiGma 25™ tableting line and a Stylcam 200R compaction simulator in several compaction force settings were performed and correlated with the porosity and hardness. It was demonstrated that OCT can easily be installed in-line and provide real-time information about critical material attributes. These insights confirm the applicability of OCT as a real-time quality control tool and its potential to replace time-consuming and destructive offline measurements.

Novel technologies for producing tridimensional cellulosic materials for packaging: A review

Petroleum-based packaging have been developed during the last century to transport and protect many products, regardless of the field of applications (food, electronics, cosmetics, leisure, etc.). Such protection has been very useful for the development of our society by favoring economic growth, limiting food waste and product deterioration, and consequently avoiding strong environmental impacts. An environmental concern has now been taken into consideration by numerous countries, with several legislations being promulgated to avoid or limit plastic waste. In this context, cellulose emerges as an alternative material for packaging applications since it is bio-based, biodegradable, and in most cases recyclable in an existing stream. However, most of the existing cellulose packaging is based on roll-to-roll 2D products or plied boxes and is not suitable to substitute plastics in 3D-shaped packaging. Recently, the interest in molded cellulose has increased exponentially thanks to new adaptations of raw materials and processes. Alternatively, research groups and companies try to adapt the injection molding to the production of cellulose-based packaging solutions. This review details for the first time the various processes and recent works in this direction. After proposing the basics of cellulose, this work focuses on the different types of molded cellulose and the novel strategies to produce 3D cellulose-based materials.

Advanced Chemical and Imaging Methods for Studying Structure Morphology and Excipients Solid State Transformations in Pharmaceutical Multiparticulate Formulations

The formulation of paediatric medicines faces significant challenges to meet the requirements for safe and accurate administration, while maintaining a suitable taste. Multiparticulate formulations have a strong potential to address these challenges because they combine dose flexibility with ease of administration. Understanding the stability of multiparticulate formulations over storage as a function of time and environmental parameters, such as humidity and temperature, is important to manage their commercialisation and use. In this work, we have expanded the toolkit of available techniques for studying multiparticulates beyond those such as scanning electron microscopy (SEM) and confocal laser scanning microscopy. We include advanced methods of environmentally-controlled SEM to monitor temperature- and humidity-induced changes in-situ, and a variety of Raman spectroscopies including stimulated Raman scattering microscopy to identify and localise the different ingredients at the surface and inside the multiparticulates. These techniques allowed unprecedented monitoring of specific changes to the particulate structure and distribution of individual ingredients due to product aging. These methods should be considered as valuable novel tools for in-depth characterisation of multiparticulate formulations to further understand chemical changes occurring during their development, manufacturing and long-term storage. We envisage these techniques to be useful in furthering the development of future medicine formulations.

Calorimetric investigation on heat release during the disintegration process of pharmaceutical tablets

The compendial USP〈701〉 disintegration test method offers a crucial pass/fail assessment for immediate release tablet disintegration. However, its single end-point approach provides limited insight into underlying mechanisms. This study introduces a novel calorimetric approach, aimed at providing comprehensive process profiles beyond binary outcomes. We developed a novel disintegration reaction calorimeter to monitor the heat release throughout the disintegration process and successfully obtained enthalpy change profiles of placebo tablets with various porosities. The formulation comprised microcrystalline cellulose (MCC), anhydrous lactose, croscarmellose sodium (CCS), and magnesium stearate (MgSt). An abrupt temperature rise was observed after introducing the disintegration medium to tablets, and the relationship between the heat rise time and the tablet's porosity was investigated. The calorimeter's sensitivity was sufficient to discern distinct heat changes among individual tablets, and the analysis revealed a direct correlation between the two. Higher porosity corresponded to shorter heat rise time, indicating faster disintegration rates. Additionally, the analysis identified a concurrent endothermic process alongside the anticipated exothermic phenomenon, potentially associated with the dissolution of anhydrous lactose. Since lactose is the only soluble excipient within the blend composition, the endothermic process can be attributed to the absorption of heat as lactose molecules dissolve in water. The findings from this study underscore the potential of utilising calorimetric methods to quantify the wettability of complex compounds and, ultimately, optimise tablet formulations.

Prediction of in-vitro dissolution and tablet hardness from optical porosity measurements

Advanced manufacturing technologies such as continuous processing require fast information on the quality of intermediates and products. Process analytical technologies (PAT) to monitor many critical quality attributes (CQAs) have been developed and successfully implemented in pharmaceutical industry. However, there are some CQAs, which still have to be measured off-line with significant effort due to the lack of suitable PAT sensors. Two prominent examples are the in-vitro dissolution and the tablet hardness. Both are obtained via destructive measurement, and the dissolution is tedious and time-consuming to determine. In this study, these two CQAs were predicted via correlation with the optical porosity of tablets. The optical porosity was measured via a novel combination of gas in scattering media absorption spectroscopy (GASMAS) and photon time of flight spectroscopy (pTOFS) with a SpectraPore instrument. The approach was tested in a continuous tableting line and showed promising results in predicting the amount of drug released after specific dissolution times as well as the tablet hardness. This indicates that the measurement of optical porosity can support control strategies within the real-time release testing (RTRT) concept.

Formation of pores and bubbles and their impacts on the quality attributes of processed foods: A review

Pores and bubbles significantly influence the physical attributes (like texture, density, and structural integrity), organoleptic properties, and shelf life of processed foods. Hence, the quality of foods and their acceptance by the consumers could be influenced by the properties and prevalence of pores and bubbles within the food structure. Considering the importance of pores, this review aimed to comprehensively discuss the factors and mechanisms involved in the generation of pores and bubbles during the processing of different food products. Moreover, the characteristics and effects of pores on the properties of chocolates, cheeses, cereal-based foods (like cake, puffed grains, and pasta), dried, and fried products were discussed. The impacts of bubbles on the quality of foam-based products, foam creamers, and beverages were also explored. This review concludes that intrinsic factors (like food compositions, initial moisture content, and porosity) and extrinsic factors (like applied technologies, processing, and storage conditions) affect various properties of the pores and bubbles including their number, size, orientation, and distribution. These factors collectively shape the overall structure and quality of processed food products such as density, texture (hardness, cohesiveness, chewiness), and water holding capacity. The desirability or undesirability of pores and their characteristics depends on the type of products; hence, some practical hints were provided to mitigate their adverse effects or to enhance their formation in foods. For example, pores could increase the nutrient digestion and reduce the shelf life of the products by enhancing the risk of fat oxidation and microbial growth. In conclusion, this study provides a valuable resource for food scientists and industry professionals by discussing the effects of pores on food preservation, heat, and mass transfer (including oxygen, moisture, flavors, and nutrients). Understanding the dynamic changes in porosity during processing will be effective in customization of final product quality with desired attributes, ensuring tailored outcomes for specific applications.

Investigating the Presence of Falsified and Poor-Quality Fixed-Dose Combination Artemether-Lumefantrine Pharmaceutical Dosage Forms in Kumasi, Ghana

Artemether-lumefantrine (AL) is a highly effective and commonly used Artemisinin-based Combination Therapy (ACT) for treating uncomplicated malaria caused by Plasmodium falciparum, including drug-resistant strains. However, ineffective regulatory systems in resource-limited settings can lead to the infiltration of poor-quality and counterfeit antimalarial medicines into the pharmaceutical supply chain, causing treatment failures, prolonged illness, and disease progression. The objective of the study was to assess the quality of selected brands of fixed-dose combination (FDC) AL tablets and suspensions marketed in Kumasi, Ghana. A total of fourteen brands of FDC AL medicines, comprising eight tablets and six suspensions were purchased from various retail pharmacy outlets in Kumasi, Ghana. All samples were subjected to thorough visual inspection as a quick means of checking quality through meticulous observation of the packaging or dosage form. The quality parameters of the tablets were determined using uniformity of weight, hardness, friability, and disintegration tests. Suspensions were assessed based on pH and compared with the British Pharmacopeia (BP) standard. The samples were then analyzed for drug content (assay) using reverse-phase high-performance liquid chromatography (RP-HPLC). All the tablet samples conformed to BP specification limits for uniformity of weight (deviation of less than ± 5%), hardness (4.0-10 kg/mm2), friability (<1%), and disintegration time (<15 minutes). The active pharmaceutical ingredients' quantitative assay demonstrated that all the tablets met the BP specifications (90-110%). The results of the pH studies showed that out of the six brands of suspension investigated, five (83.3%) were compliant with the official specification for pH, while one (16.7%) failed the requirement. Unlike the tablet brands, drug content analysis of the six suspensions showed that two (33.3%) were substandard. The artemether and lumefantrine contents in these failed suspensions were variable (artemether: 81.31%-116.76%; lumefantrine: 80.35%-99.71%). The study results indicate that most of the tested products met the required quality standards, demonstrating satisfactory drug content and other quality specifications. The presence of substandard drugs underscores the necessity for robust pharmacovigilance and surveillance systems to eliminate counterfeit and substandard drugs from the Ghanaian market.

Semi-crystalline materials for pharmaceutical fused filament fabrication: Dissolution and porosity

A better understanding of crystallization kinetics and the effect on drug product quality characteristics is needed to exploit the use of semi-crystalline polymers in pharmaceutical fused filament fabrication. Filaments were prepared from polycaprolactone or polyethylene oxide loaded with a crystallization inhibitor or inducer, which was either 10% (w/w) ibuprofen or theophylline. A design-of-experiments approach was conducted to investigate the effect of nozzle temperature, bed temperature and print speed on the printed tablets' microstructure and dissolution kinetics. Helium pycnometry derived porosity proved an ideal technique to capture significant distortions in the tablets' microstructure. On the other hand, terahertz time domain spectroscopy (THz-TDS) analysis proved valuable to investigate additional enclosed pores of the tablets' microstructure. The surface roughness was analyzed using optical coherence tomography, showing the importance of extensional viscosity for printed drug products. Drug release occurred via erosion for tablets consisting of polyethylene oxide, which partly reduced the effect of the inner microstructure on the drug release kinetics. An initial burst release effect was noted for polycaprolactone tablets, after which drug release continued via diffusion. Both the pore and crystalline microstructure were deemed essential to steer drug release. In conclusion, this research provided guidelines for material and process choice when a specific microstructure has to be constructed from semi-crystalline materials. In addition, non-destructive tests for the characterization of printed products were evaluated.

Impact of drug load and polymer molecular weight on the 3D microstructure of printed tablets

This study investigates the influence of drug load and polymer molecular weight on the structure of tablets three-dimensionally (3D) printed from the binary mixture of prednisolone and hydroxypropyl methylcellulose (HPMC). Three different HPMC grades, (AFFINISOLTM HPMC HME 15LV, 90 Da (HPMC 15LV); 100LV, 180 Da (HPMC 100LV); 4M, 500 Da (HPMC 4M)), which are suitable for hot-melt extrusion (HME), were used in this study. HME was used to fabricate feedstock material, i.e., filaments, at the lowest possible extrusion temperature. Filaments of the three HPMC grades were prepared to contain 2.5, 5, 10 and 20 % (w/w) prednisolone. The thermal degradation of the filaments was studied with thermogravimetric analysis, while solid-state properties of the drug-loaded filaments were assessed with the use of X-ray powder diffraction. Prednisolone in the freshly extruded filaments was determined to be amorphous for drug loads up to 10%. It remained physically stable for at least 6 months of storage, except for the filament containing 10% drug with HPMC 15LV, where recrystallization of prednisolone was detected. Fused deposition modeling was utilized to print honeycomb-shaped tablets from the HME filaments of HPMC 15LV and 100LV. The structural characteristics of the tablets were evaluated using X-ray microcomputed tomography, specifically porosity and size of structural elements were investigated. The tablets printed from HPMC 15LV possessed in general lower total porosity and pores of smaller size than tablets printed from the HPMC 100LV. The studied drug loads were shown to have minor effect on the total porosity of the tablets, though the lower the drug load was, the higher the variance of porosity along the height of the tablet was observed. It was found that tablets printed with HPMC 15LV showed higher structural similarity with the virtually designed model than tablets printed from HPMC 100LV. These findings highlight the relevance of the drug load and polymer molecular weight on the microstructure and structural properties of 3D printed tablets.

At-line porosity sensing for non-destructive disintegration testing in immediate release tablets

Fully automated at-line terahertz time-domain spectroscopy in transmission mode is used to measure tablet porosity for thousands of immediate release tablets. The measurements are rapid and non-destructive. Both laboratory prepared tablets and commercial samples are studied. Multiple measurements on individual tablets quantify the random errors in the terahertz results. These show that the measurements of refractive index are precise, with the standard deviation on a single tablet being about 0.002, with variation between measurements being due to small errors in thickness measurement and from the resolution of the instrument. Six batches of 1000 tablets each were directly compressed using a rotary press. The tabletting turret speed (10 and 30 rpm) and compaction pressure (50, 100 and 200 MPa) were varied between the batches. As expected, the tablets compacted at the highest pressure have far lower porosity than those compacted at the lowest pressure. The turret rotation speed also has a significant effect on porosity. This variation in process parameters resulted in batches of tablets with an average porosity between 5.5 and 26.5%. Within each batch, there is a distribution of porosity values, the standard deviation of which is in the range 1.1 to 1.9%. Destructive measurements of disintegration time were performed in order to develop a predictive model correlating disintegration time and tablet porosity. Testing of the model suggested it was reasonable though there may be some small systematic errors in disintegration time measurement. The terahertz measurements further showed that there are changes in tablet properties after storage for nine months in ambient conditions.

Evolution characteristics of micromechanics provides insights into the microstructure of pharmaceutical tablets fabricated by bimodal mixtures

This research focuses on the evolution of mechanical behavior of bimodal mixtures undergoing compaction and diametrical compression. The clusters were built and discrete element method (DEM) was used to investigate the densification process and micromechanics of bimodal mixtures. Additionally, a more comprehensive investigate of the respective breakage of the bimodal mixtures has been carried out. On this basis, qualitative and quantitative analysis of the compressive force, force chain, contact bonds and density field evolution characteristics of the clusters are investigated during the compression process. The entire loading process of the clusters is divided into three stages: rearrangement, breakage and elastic-plastic deformation. Additionally, there are differences in the evolution of micromechanics behavior of different particles in the bimodal mixture, with pregelatinized starch breakage and deformation occurring before microcrystalline cellulose. With the tablet deformation, the fragmentation process of the tablet started at the point of contact and extended toward the center, and the curvature of the force chain increased. This approach may potentially hold a valuable new information relevant to important transformation forms batch manufacturing to advanced manufacturing for the oral solid dosage form.

Development of an Image-based Method for Tablet Microstructure Description and Its Correlation with API Release Rate

The performance of a pharmaceutical formulation, such as the drug (API) release rate, is significantly influenced by the properties of the materials used, the composition of the final product and the tablet compression process parameters. However, in some cases, the knowledge of these input parameters does not necessarily provide a reliable description or prediction of tablet performance. Therefore, the knowledge of tablet microstructure is desirable to understand such formulations. Commonly used analytical techniques, such as X-ray tomography and intrusion mercury porosimetry, are not widely used in pharmaceutical companies due to their price and/or toxicity, and therefore, efforts are made to develop a tool for fast and easy microstructure description. In this work, we have developed an image-based method for microstructure description and applied it to a model system consisting of ibuprofen and CaHPO4∙2H2O (API and excipient with different deformability). The obtained parameter, the quadratic mean of the equivalent diameter of the non-deformable, brittle excipient CaHPO4∙2H2O, was correlated with tablet composition, compression pressure and API release rate. The obtained results demonstrate the possibility of describing the tablet dissolution performance in the presented model system based on the microstructural parameter, providing a possible model system for compressed solid dosage forms in which a plastic component is present and specific API release is required.

Prediction of Dissolution Performance of Uncoated Solid Oral Dosage Forms via Optical Coherence Tomography

Real-time prediction of the dissolution behavior of solid oral dosage forms is an important research topic. Although methods such as Terahertz and Raman can provide measurements that can be linked to the dissolution performance, they typically require a longer time off-line for analysis. In this paper, we present a novel strategy for analyzing uncoated compressed tablets by means of optical coherence tomography (OCT). Using OCT, which is fast and in-line capable, makes it possible to predict the dissolution behavior of tablets based on images. In our study, OCT images were obtained of individual tablets from differently produced batches. Differences between tablets or batches in these images were hardly visible to the human eye. Advanced image analysis metrics were developed to quantify the light scattering behavior captured by the OCT probe and depicted in the OCT images. Detailed investigations assured the repeatability and robustness of the measurements. A correlation between these measurements and the dissolution behavior was established. A tree-based machine learning model was used to predict the amount of dissolved active pharmaceutical ingredient (API) at certain time points for each immediate-release tablet. Our results indicate that OCT, which is a non-destructive and real-time technology, can be used for in-line monitoring of tableting processes.

Investigating the function and design of molecular materials through terahertz vibrational spectroscopy

Terahertz spectroscopy has proved to be an essential tool for the study of condensed phase materials. Terahertz spectroscopy probes the low-frequency vibrational dynamics of atoms and molecules, usually in the condensed phase. These nuclear dynamics, which typically involve displacements of entire molecules, have been linked to bulk phenomena ranging from phase transformations to semiconducting efficiency. The terahertz region of the electromagnetic spectrum has historically been referred to as the 'terahertz gap', but this is a misnomer, as there exist a multitude of methods for accessing terahertz frequencies, and now there are cost-effective instruments that have made terahertz studies much more user-friendly. This Review highlights some of the most exciting applications of terahertz vibrational spectroscopy so far, and provides an in-depth overview of the methods of this technique and its utility to the study of the chemical sciences.

Enhanced in-situ liquid transport investigation setup for pharmaceutical tablet disintegration analysis using terahertz radiation

The disintegration process of pharmaceutical solid dosage forms commences on contact with the dissolution medium and continues with subsequent spontaneous imbibition of the medium in the tablet matrix. Identifying the location of the liquid front in situ during imbibition, therefore, plays a significant role in understanding and modelling the disintegration process. Terahertz pulsed imaging (TPI) technology can be used to investigate this process by its ability to penetrate and identify the liquid front in pharmaceutical tablets. However, previous studies were limited to samples suitable for a flow cell environment, i.e. flat cylindrical disk shapes; thus, most commercial tablets could only be measured with prior destructive sample preparation. This study presents a new experimental setup named open immersion to measure a wide range of pharmaceutical tablets in their intact form. Besides, a series of data processing techniques to extract subtle features of the advancing liquid front are designed and utilised, effectively increasing the maximum thickness of tablets that can be analysed. We used the new method and successfully measured the liquid ingress profiles for a set of oval convex tablets prepared from a complex eroding immediate-release formulation.

Production challenges of tablets containing lipid excipients: Case study using cannabidiol as drug model

The aims of this study were, firstly, to select an optimal lipid solid dispersion of cannabidiol among different lipid excipients (Gelucire® 50/13, 48/16, 44/14 and Labrasol®) and inorganic carriers (colloidal silica, Syloid® XDP and Neusilin® US2) through a screening plan. The enhancement of aqueous solubility of cannabidiol from a free-flowing powder with adequate drug content was obtained by mixing cannabidiol (20%) with Gelucire® 50/13 (40%; Gattefossé, France), both incorporated inside mesopores of mesoporous silica Syloid® XDP (40%; Grace, Germany). Secondly, we have studied the tableting properties of this selected dispersion through a Design of Experiments (DoE) by manufacturing tablets with other excipients with using a compression simulator (Styl'One® Evo, Medelpharm, France). The design of experiments included the percentage of lipid solid dispersion, of glidant, of lubricant and different compression forces. The dissolution efficiency, the drug content, the tensile strength and the ejection force were analyzed. The DoE showed that % of dispersion as well as compression forces were the main influential variables. An exit of lipid materials outside the mesopores of silica due to compression process has been highlighted, reflected by reduced tensile strength. This study showed the possibility of manufacturing tablets with lipid materials even if limitations have been highlighted. Indeed, the dispersion percentage must not exceed 27% and compression forces up to 13 kN are required to produce lipid tablets with optimal properties.

Modelling the Evolution of Pore Structure during the Disintegration of Pharmaceutical Tablets

Pharmaceutical tablet disintegration is a critical process for dissolving and enabling the absorption of the drug substance into the blood stream. The tablet disintegration process consists of multiple connected and interdependent mechanisms: liquid penetration, swelling, dissolution, and break-up. One key dependence is the dynamic change of the pore space in a tablet caused by the swelling of particles while the tablet takes up liquid. This study analysed the changes in the pore structure during disintegration by coupling the discrete element method (DEM) with a single-particle swelling model and experimental liquid penetration data from terahertz-pulsed imaging (TPI). The coupled model is demonstrated and validated for pure microcrystalline cellulose (MCC) tablets across three porosities (10, 15, and 22%) and MCC with three different concentrations of croscarmellose sodium (CCS) (2, 5, and 8% w/w). The model was validated using experimental tablet swelling from TPI. The model captured the difference in the swelling behaviour of tablets with different porosities and formulations well. Both the experimental and modelling results showed that the swelling was lowest (i.e., time to reach the maximum normalised swelling capacity) for tablets with the highest CCS concentration, cCCS = 8%. The simulations revealed that this was caused by the closure of the pores in both the wetted volume and dry volume of the tablet. The closure of the pores hinders the liquid from accessing other particles and slows down the overall swelling process. This study provides new insights into the changes in the pore space during disintegration, which is crucial to better understand the impact of porosity and formulations on the performance of tablets.

Versatile and active THz wave polarization modulators using metamaterial/graphene resonators

Active modification of the polarization state is a key feature for the next-generation of wireless communications, sensing, and imaging in the THz band. The polarization modulation performance of an integrated metamaterial/graphene device is investigated via a modified THz time domain spectroscopic system. Graphene’s Fermi level is modified through electrostatic gating, thus modifying the device’s overall optical response. Active tuning of ellipticity by >0.3 is reported at the resonant frequency of 0.80 THz. The optical activity of transmitted THz radiations is continuously modified by >21.5o at 0.71 THz. By carefully selecting the transmitted frequency with the relative angle between the incoming linear polarization and the device’s symmetry axis, active circular dichroism and optical activity are almost independently exploited. Finally, this all-electronically tuneable versatile polarization device can be used in all applications requiring an ultrafast modulation such as polarization spectroscopy, imaging, and THz wireless generation.

Role of Microstructure in Drug Release from Chitosan Amorphous Solid Dispersions

The unexpected dissolution behaviour of amorphous diflunisal-chitosan solid dispersions (kneading method) with respect to the crystalline co-evaporated systems is the starting point of this research. This work is an in-depth study of the diflunisal release behaviour from either chitosan or carboxymethylchitosan dispersions. The microstructure is not usually considered when designing this type of products; however, it is essential to understand the process of solvent penetration and subsequent drug release through a polymeric system, as has been evidenced in this study. In accordance with the kinetic data analysed, it is possible to conclude that the porous structure, conditioned by the sample preparation method, can be considered the main factor involved in diflunisal release. The low mean pore size (1-2 μm), low porosity, and high tortuosity of the amorphous kneaded products are responsible for the slow drug release in comparison with the crystalline coevaporated systems, which exhibit larger pore size (8-10 μm) and lower tortuosity. Nevertheless, all diflunisal-carboxymethylchitosan products show similar porous microstructure and overlapping dissolution profiles. The drug release mechanisms obtained can also be related to the porous structure. Fickian diffusion was the main mechanism involved in drug release from chitosan, whereas an important contribution of erosion was detected for carboxymethylchitosan systems, probably due to its high solubility.

Development of Flow-Through Cell Dissolution Method for In Situ Visualization of Dissolution Processes in Solid Dosage Forms Using X-ray μCT

Visualization of the dynamic behavior of pharmaceutical dosage forms during the dissolution process offers a better understanding of the drug release mechanism, enabling the design of customized dosage forms. In this study, an X-ray tomography-based approach is proposed to monitor and analyze the dynamics of the structure at the pore scale level during the dissolution process. A flow-through cell dissolution apparatus was developed, capable of mimicking the standard in vitro dissolution process, which can be easily positioned in an X-ray tomography setup. The method was utilized to study the dissolution of a Capa^® (polycaprolactone)-based sustained-release 3D printed tablet. The impact of the flow rate on the active pharmaceutical ingredient (API) release rate was studied and 16 mL/min was selected as a suitable flow rate. Furthermore, cesium chloride (CsCl) was used as a contrast agent to increase the contrast between the sample and the dissolution medium. Data obtained with this novel technique were in a good agreement with the released drug rate acquired by the standard in vitro dissolution test (the similarity factor (f2) = 77%). Finally, the proposed approach allowed visualizing the internal structure of the sample, as well as real-time tracking of solution ingress into the product.

New Insight into the Impact of Effervescence on Gel Layer Microstructure and Drug Release of Effervescent Matrices Using Combined Mechanical and Imaging Characterisation Techniques

Gel layer characteristics play a crucial role in hydrophilic hydroxypropyl methylcellulose (HPMC) matrix development. Effervescent agents have the potential to affect the gel layer microstructures. This study aimed to investigate the influence of effervescence on the microstructure of the gel layer around HPMC matrices using a combination of texture analysis and imaging techniques. The relationship with drug release profile and release mechanisms were also examined. The high amounts of effervescent agents promoted a rapid carbonation reaction, resulting in a high gel layer formation with a low gel strength through texture analysis. This finding was ascribed to the enhanced surface roughness and porosity observed under digital microscopy and microporous structure of the gel layer under scanning electron microscopy. The reconstructed three-dimensional images from synchrotron radiation X-ray tomographic microscopy notably exhibited the interconnected pores of various sizes from the carbonation reaction of effervescent and microporous networks, indicating the gel layer on the tablet surface. Notably, effervescence promoted the increase in interconnected porosities, which directly influenced the strength of the gel layer microstructure, drug release patterns and release mechanism of the effervescent matrix tablet. Therefore, combined mechanical characterisation and imaging techniques can provide new insights into the role of effervescent agents on the gel layer microstructure, and describe the relationship of drug release patterns and release mechanism of matrix tablets.

Drug-Polymers Composite Matrix Tablets: Effect of Hydroxypropyl Methylcellulose (HPMC) K-Series on Porosity, Compatibility, and Release Behavior of the Tablet Containing a BCS Class I Drug

The purpose of this research was to see how the physicochemical properties and porosity of matrix tablets containing various types of hydroxypropyl methylcellulose (HPMC) K series affected the release of propranolol hydrochloride (PNL). PNL is a class I drug (high solubility and permeability) according to the Biopharmaceutics Classification System (BCS), making it an excellent model drug used for studying extended-release drug products. The direct compression method was used to prepare the HPMC-based matrix tablets. PNL and the excipients were found to be compatible using Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), and differential scanning calorimetry (DSC). The surfaces of all the compressed HPMC-based matrix tablets were rough, with accumulated particles and small holes. The compressed HPMC-based matrix tablet porosity was also determined by using mercury porosimetry. The compressed HPMC-based matrix tablets made of low viscosity HPMC had tiny pores (diameter < 0.01 μm). The shorter polymeric chains are more prone to deformation, resulting in a small pore proportion. The compressed HPMC-based matrix tablets sustained the release of PNL for over 12 h. The release exponent values (n), which reflect the release mechanism of the drug from the tablets, ranged from 0.476 to 0.497. These values indicated that the release was governed by anomalous transport. The compressed HPMC-based matrix tablets have the potential for a sustained release of PNL.

A generalized image analytical algorithm for investigating tablet disintegration

Commonly used methods for analyzing tablet disintegration are based on visual observations and can thus be user-dependent. To address this, a generally applicable image analytical algorithm has been developed for machine vision-based quantification of tablet disintegration. The algorithm has been tested with a conventional immediate release tablet, as well as model compacts disintegrating mainly through erosion, and finally, with a polymeric slow-release system. Despite differences in disintegration mechanisms between these compacts, the developed image analytical algorithm demonstrated its general applicability through quantifying the extent of disintegration without adaptation of image analytical parameters. The reproducibility of the approach was estimated with commercial tablets, and further, it could differentiate a range of different model compacts. The developed image analytical algorithm mimics the human decision-making processes and the current experience-based visual evaluation of disintegration time. In doing so the algorithmic method allows a user-independent approach for development of the optimal tablet formulation as well as gaining an understanding on how the selection of excipients and manufacturing processes ultimately influences tablet disintegration.

Polymer Pellet Fabrication for Accurate THz-TDS Measurements

We investigate fabrication of compacts using polytetrafluoroethylene (PTFE) and polyethylene (PE), and the effect of compaction conditions on their terahertz transmission properties. The conditions used to fabricate compressed powder samples for terahertz time-domain spectroscopy (THz-TDS) can impact the accuracy of the measurements and hence the interpretation of results. This study investigated the effect of compaction conditions on the accuracy of the THz-TDS analysis. Two polymers that are commonly used as matrix materials in terahertz spectroscopy studies were explored using a compaction simulator and a hydraulic press for sample preparation. THz-TDS was used to determine the refractive index and loss coefficient to compare the powder compacts (pellets) to the values of solid material. Sample porosity, axial relaxation and tensile strength were measured to assess the material’s suitability for terahertz spectroscopy. It was found that PTFE is the preferable material for creating THz-TDS samples due to its low porosity and high tensile strength. PE was found to show significant porosity at all compaction pressures, making it an unsuitable material for the accurate determination of optical parameters from THz-TDS spectroscopy measurements. The larger particle sizes of PE resulted in compacts that exhibited significantly lower tensile strength than those made from PTFE making handling and storage difficult.

Non-Destructive Porosity Measurements of 3D Printed Polymer by Terahertz Time-Domain Spectroscopy

The porosity and inhomogeneity of 3D printed polymer samples were examined using terahertz time-domain spectroscopy, and the effects of 3D printer settings were analysed. A set of PETG samples were 3D printed by systematically varying the printer parameters, including layer thickness, nozzle diameter, filament (line) thickness, extrusion, and printing pattern. Their effective refractive indices and loss coefficients were measured and compared with those of solid PETG. Porosity was calculated from the refractive index. A diffraction feature was observed in the loss spectrum of all 3D printed samples and was used as an indication of inhomogeneity. A “sweet spot” of printer settings was found, where porosity and inhomogeneity were minimised.

Terahertz time-domain spectroscopy for powder compact porosity and pore shape measurements: An error analysis of the anisotropic bruggeman model

Terahertz time-domain spectroscopy (THz-TDS) is a novel technique which has been applied for pore structure analysis and porosity measurements. For this, mainly the anisotropic Bruggeman (AB-EMA) model is applied to correlate the effective refractive index (n eff) of a tablet and the porosity as well as to evaluate the pore shape based on the depolarisation factor L. This paper investigates possible error sources of the AB-EMA for THz-TDS based tablet analysis. The effect of absorption and tablet anisotropy - changes of pore shape with porosity and density distribution - have been investigated. The results suggest that high tablet absorption has a negligible effect on the accuracy of the AB-EMA. In regards of tablet anisotropy the accuracy of the porosity determination is not impaired significantly. However, density distribution and variations in the pore shape with porosity resulted in an unreliable extraction of the tablet pore shape. As an extension of the AB-EMA a new concept was introduced to convert the model into bounds for L. This new approach was found useful to investigate tablet pore shape but also the applicability of the AB-EMA for an unknown set of data.

Polymers in pharmaceutical additive manufacturing: A balancing act between printability and product performance

Materials and manufacturing processes share a common purpose of enabling the pharmaceutical product to perform as intended. This review on the role of polymeric materials in additive manufacturing of oral dosage forms, focuses on the interface between the polymer and key stages of the additive manufacturing process, which determine printability. By systematically clarifying and comparing polymer functional roles and properties for a variety of AM technologies, together with current and emerging techniques to characterize these properties, suggestions are provided to stimulate the use of readily available and sometimes underutilized pharmaceutical polymers in additive manufacturing. We point to emerging characterization techniques and digital tools, which can be harnessed to manage existing trade-offs between the role of polymers in printer compatibility versus product performance. In a rapidly evolving technological space, this serves to trigger the continued development of 3D printers to suit a broader variety of polymers for widespread applications of pharmaceutical additive manufacturing.

Selective Laser Sintering (SLS), a New Chapter in the Production of Solid Oral Forms (SOFs) by 3D Printing

3D printing is a new emerging technology in the pharmaceutical manufacturing landscape. Its potential advantages for personalized medicine have been widely explored and commented on in the literature over recent years. More recently, the selective laser sintering (SLS) technique has been investigated for oral drug-delivery applications. Thus, this article reviews the work that has been conducted on SLS 3D printing for the preparation of solid oral forms (SOFs) from 2017 to 2020 and discusses the opportunities and challenges for this state-of-the-art technology in precision medicine. Overall, the 14 research articles reviewed report the use of SLS printers equipped with a blue diode laser (445-450 nm). The review highlights that the printability of pharmaceutical materials, although an important aspect for understanding the sintering process has only been properly explored in one article. The modulation of the porosity of printed materials appears to be the most interesting outcome of this technology for pharmaceutical applications. Generally, SLS shows great potential to improve compliance within fragile populations. The inclusion of "Quality by Design" tools in studies could facilitate the deployment of SLS in clinical practice, particularly where Good Manufacturing Practices (GMPs) for 3D-printing processes do not currently exist. Nevertheless, drug stability and powder recycling remain particularly challenging in SLS. These hurdles could be overcome by collaboration between pharmaceutical industries and compounding pharmacies.

Influence of Drug Load on the Printability and Solid-State Properties of 3D-Printed Naproxen-Based Amorphous Solid Dispersion

Fused deposition modelling-based 3D printing of pharmaceutical products is facing challenges like brittleness and printability of the drug-loaded hot-melt extruded filament feedstock and stabilization of the solid-state form of the drug in the final product. The aim of this study was to investigate the influence of the drug load on printability and physical stability. The poor glass former naproxen (NAP) was hot-melt extruded with Kollidon^® VA 64 at 10–30% w/w drug load. The extrudates (filaments) were characterised using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). It was confirmed that an amorphous solid dispersion was formed. A temperature profile was developed based on the results from TGA, DSC, and DMA and temperatures used for 3D printing were selected from the profile. The 3D-printed tablets were characterised using DSC, X-ray computer microtomography (XµCT), and X-ray powder diffraction (XRPD). From the DSC and XRPD analysis, it was found that the drug in the 3D-printed tablets (20 and 30% NAP) was amorphous and remained amorphous after 23 weeks of storage (room temperature (RT), 37% relative humidity (RH)). This shows that adjusting the drug ratio can modulate the brittleness and improve printability without compromising the physical stability of the amorphous solid dispersion.

The use of X-ray microtomography to investigate the microstructure of pharmaceutical tablets: Potentials and comparison to common physical methods

Within this study, tablets microstructure was investigated by X-ray microtomgraphy. The aim was to gain information about their microstructure, and thus, derive deeper interpretation of tablet properties (mechanical strength, component distribution) and qualified property functions. Challenges in image processing are discussed for the correct identification of solids and voids. Furthermore, XMT measurements are critically compared with complementary physical methods for characterizing active pharmaceutical ingredient (API) content and porosity and its distribution (mercury porosimetry, calculated tablet porosity, Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM)). The derived porosity by XMT is generally lower than the calculated porosity based on geometrical data due to the resolution of the XMT in relation to the pore sizes in tablets. With rising compactions stress and API concentration, deviations between the actual and the calculated API decrease. XMT showed that API clusters are present for all tablets containing >1 wt% of ibuprofen. The 3D orientation of the components is assessable by deriving cord lengths along all dimensions of the tablets. An increasing compaction stress leads to rising cord lengths, showing higher connectivity of the respective material. Its lesser extent in the z-direction illustrates the anisotropy of the compaction process. Additionally, cracks in the fabric are identified in tablets without visible macroscopic damage. Finally, the application of XMT provides valuable structural insights if its limitations are taken into account and its strengths are fostered by advanced pre- and post-processing.

Characterizing the Impact of Spray Dried Particle Morphology on Tablet Dissolution Using Quantitative X-Ray Microscopy

For oral solid dosage forms, disintegration and dissolution properties are closely related to the powders and particles used in their formulation. However, there remains a strong need to characterize the impact of particle structures on tablet compaction and performance. Three-dimensional non-invasive tomographic imaging plays an increasingly essential role in the characterization of drug substances, drug product intermediates, and drug products. It can reveal information hidden at the micro-scale which traditional characterization approaches fail to divulge due to a lack of resolution. In this study, two batches of spray-dried particles (SDP) and two corresponding tablets of an amorphous product, merestinib (LY2801653), were analyzed with 3D X-Ray Microscopy. Artificial intelligence-based image analytics were used to quantify physical properties, which were then correlated with dissolution behavior. The correlation derived from the image-based characterization was validated with conventional laboratory physical property measurements. Quantitative insights obtained from image-analysis including porosity, pore size distribution, surface area and pore connectivity helped to explain the differences in dissolution behavior between the two tablets, with root causes traceable to the microstructure differences in their corresponding SDPs.

Insights into the Control of Drug Release from Complex Immediate Release Formulations

The kinetics of water transport into tablets, and how it can be controlled by the formulation as well as the tablet microstructure, are of central importance in order to design and control the dissolution and drug release process, especially for immediate release tablets. This research employed terahertz pulsed imaging to measure the process of water penetrating through tablets using a flow cell. Tablets were prepared over a range of porosity between 10% to 20%. The formulations consist of two drugs (MK-8408: ruzasvir as a spray dried intermediate, and MK-3682: uprifosbuvir as a crystalline drug substance) and NaCl (0% to 20%) at varying levels of concentrations as well as other excipients. A power-law model is found to fit the liquid penetration exceptionally well (average R2>0.995). For each formulation, the rate of water penetration, extent of swelling and the USP dissolution rate were compared. A factorial analysis then revealed that the tablet porosity was the dominating factor for both liquid penetration and dissolution. NaCl more significantly influenced liquid penetration due to osmotic driving force as well as gelling suppression, but there appears to be little difference when NaCl loading in the formulation increases from 5% to 10%. The level of spray dried intermediate was observed to further limit the release of API in dissolution.

New Characterization Measures of Pore Shape and Connectivity Applied to Coatings used for Controlled Drug Release

Pore geometry characterization-methods are important tools for understanding how pore structure influences properties such as transport through a porous material. Bottlenecks can have a large influence on transport and related properties. However, existing methods only catch certain types of bottleneck effects caused by variations in pore size. We here introduce a new measure, geodesic channel strength, which captures a different type of bottleneck effect caused by many paths coinciding in the same pore. We further develop new variants of pore size measures and propose a new way of visualizing 3-D characterization results using layered images. The new measures together with existing measures were used to characterize and visualize properties of 3-D FIB-SEM images of three leached ethyl-cellulose/hydroxypropyl-cellulose films. All films were shown to be anisotropic, and the strongest anisotropy was found in the film with lowest porosity. This film had very tortuous paths and strong geodesic channel-bottlenecks, while the paths through the other two films were relatively straight with well-connected pore networks. The geodesic channel strength was shown to give important new visual and quantitative insights about connectivity, and the new pore size measures provided useful information about anisotropies and inhomogeneities in the pore structures. The methods have been implemented in the freely available software MIST.

A Fast and Non-destructive Terahertz Dissolution Assay for Immediate Release Tablets

There is a clear need for a robust process analytical technology tool that can be used for on-line/in-line prediction of dissolution and disintegration characteristics of pharmaceutical tablets during manufacture. Tablet porosity is a reliable and fundamental critical quality attribute which controls key mass transport mechanisms that govern disintegration and dissolution behavior. A measurement protocol was developed to measure the total porosity of a large number of tablets in transmission without the need for any sample preparation. By using this fast and non-destructive terahertz spectroscopy method it is possible to predict the disintegration and dissolution of drug from a tablet in less than a second per sample without the need of a chemometric model. The validity of the terahertz porosity method was established across a range of immediate release (IR) formulations of ibuprofen and indomethacin tablets of varying geometries as well as with and without debossing. Excellent correlation was observed between the measured terahertz porosity, dissolution characteristics (time to release 50% drug content) and disintegration time for all samples. These promising results and considering the robustness of the terahertz method pave the way for a fully automated at-line/on-line porosity sensor for real time release testing of IR tablets dissolution.