SeDeM expert system for directly compressed tablet formulation: A review and new perspectives

Mannitol-coated hydroxypropyl methylcellulose as an alternative directly compressible controlled release excipient

One of the most common forms of controlled release technology for oral drug delivery comprises an active ingredient dispersed in a hydrophilic matrix forming polymer such as hydroxypropyl methylcellulose (HPMC), which is tableted via direct compression. However, HPMC may pose problems in direct compression due to its poor flowability. Hence, mannitol syrup was spray-coated over fluidized HPMC particles to produce co-processed HPMC-mannitol at ratios of 20:80, 50:50, and 70:30. Particles of pure HPMC, co-processed HPMC-mannitol, and their respective physical mixtures were evaluated for powder flowability, compression profiles, and controlled release performance. It was found that co-processed HPMC-mannitol consisted of particles with improved flow compared to pure HPMC particles. Sufficiently strong tablets of >2 MPa could be produced at moderate to high compression forces of 150-200 MPa. The dissolution profile could be tuned to obtain desired release profiles by altering HPMC-mannitol ratios. Co-processed HPMC-mannitol offers an interesting addition to the formulator's toolbox in the design of controlled release formulations for direct compression.

Ten years of the manufacturing classification system: a review of literature applications and an extension of the framework to continuous manufacture

The MCS initiative was first introduced in 2013. Since then, two MCS papers have been published: the first proposing a structured approach to consider the impact of drug substance physical properties on manufacturability and the second outlining real world examples of MCS principles. By 2023, both publications had been extensively cited by over 240 publications. This article firstly reviews this citing work and considers how the MCS concepts have been received and are being applied. Secondly, we will extend the MCS framework to continuous manufacture. The review structure follows the flow of drug product development focussing first on optimisation of API properties. The exploitation of links between API particle properties and manufacturability using large datasets seems particularly promising. Subsequently, applications of the MCS for formulation design include a detailed look at the impact of percolation threshold, the role of excipients and how other classification systems can be of assistance. The final review section focusses on manufacturing process development, covering the impact of strain rate sensitivity and modelling applications. The second part of the paper focuses on continuous processing proposing a parallel MCS framework alongside the existing batch manufacturing guidance. Specifically, we propose that continuous direct compression can accommodate a wider range of API properties compared to its batch equivalent.

Rapid characterization of physical properties for the pharmaceutical pellet cores based on NIR spectroscopy and ensemble learning

During the development of sustained-release pellets, the physical characteristics of the pellet cores can affect drug release in the preparation. The method based on near-infrared (NIR) spectroscopy and ensemble learning was proposed to swiftly assess the physical properties of the pellet cores. In the research, the potential of three algorithms, direct standardization (DS), partial least squares regression (PLSR) and generalized regression neural network (GRNN), was investigated and compared. The performance of the DS, PLSR and GRNN models were improved after applying bootstrap aggregating (Bagging) ensemble learning. And the Bagging-GRNN model showed the best predictive capacity. Except for inter-particle porosity, the mean absolute deviations of other 11 physical parameters were less than 1.0. Furthermore, the cosine coefficient values between the actual and predicted physical fingerprints was higher than 0.98 for 15 out of the 16 validation samples when using the Bagging-GRNN model. To reduce the model complexity, the 60 variables significantly correlated with angle of repose, particle size (D50) and roundness were utilized to develop the simplified Bagging-GRNN model. And the simplified model showed satisfactory predictive capacity. In summary, the developed ensemble modelling strategy based NIR spectra is a promising approach to rapidly characterize the physical properties of the pellet cores.

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.

A tabletability change classification system in supporting the tablet formulation design via the roll compaction and dry granulation process

In this paper, the material library approach was used to uncover the pattern of tabletability change and related risk for tablet formulation design under the roll compaction and dry granulation (RCDG) process. 31 materials were fully characterized using 18 physical parameters and 9 compression behavior classification system (CBCS) parameters. Then, each material was dry granulated and sieved into small granules (125-250 μm) and large granules (630-850 μm), respectively. The compression behavior of granules was characterized by the CBCS descriptors, and were compared with that of ungranulated powders. The relative change of tabletability (CoTr) index was used to establish the tabletability change classification system (TCCS), and all materials were classified into three types, i.e. loss of tabletability (LoT, Type I), unchanged tabletability (Type II) and increase of tabletability (Type III). Results showed that approximately 65% of materials presented LoT, and as the granules size increased, 84% of the materials exhibited LoT. A risk decision tree was innovatively proposed by joint application of the CBCS tabletability categories and the TCCS tabletability change types. It was found that the LoT posed little risk to the tensile strength of the final tablet, when Category 1 or 2A materials, or Category 2B materials with Type II or Type III change of tabletability were used. Formulation risk happened to Category 2C or 3 materials, or Category 2B materials with Type I change of tabletability, particularly when high proportions of these materials were involved in tablet formulation. In addition, the risk assessment results were verified in the material property design space developed from a latent variable model in prediction of tablet tensile strength. Overall, results suggested that a combinational use of CBCS and TCCS could aid the decision making in selecting materials for tablet formulation design via RCDG.

An overview of the implementation of SeDeM and SSCD in various formulation developments

The Sediment Delivery Model explains experimental analysis and quantitative assessment of the powdered substance characterizing parameters, which offer pertinent data about the material's appropriateness for direct compression (DC) of tablet, which involves mathematical modeling and Semisolid Control Diagram using software like iTCM. The SeDeM diagram expert system (DES) determines the suitability of excipients and active ingredients for DC and the ratio of API to excipient is calculated. The DC is most suitable as it saves time and makes process easy, but these technique excipients compensate for their poor flow. Thus, a new system was required to help reduce number of experiments and time for making an optimized direct compression tablet. The SeDeM DES is based on quality by design (QbD) (ICH Q8) as it evaluates critical quality attributes that affect finished product's quality. This review mainly focuses on various dosage forms like Solid, Semisolid, Liquisolid, and Solidified liquid dosage forms. These techniques mainly characterize all substances using 12 parameters, resulting 12-sided regular polygon. However, parameters may increase or decrease according to the requirement of a particular dosage form like an Orodispersible tablet 15 and a Semisolid dosage form applying 5 parameters. The rationales behind limits for indexes are justified accordingly.

Using a Material Library to Understand the Change of Tabletability by High Shear Wet Granulation

Understanding the tabletability change of materials after granulation is critical for the formulation and process design in tablet development. In this paper, a material library consisting of 30 pharmaceutical materials was used to summarize the pattern of change of tabletability during high shear wet granulation and tableting (HSWGT). Each powdered material and the corresponding granules were characterized by 19 physical properties and nine compression behavior classification system (CBCS) parameters. Principal component analysis (PCA) was used to compare the physical properties and compression behaviors of ungranulated powders and granules. A new index, namely the relative change of tabletability (CoT_r), was proposed to quantify the tabletability change, and its advantages over the reworking potential were demonstrated. On the basis of CoT_r values, the tabletability change classification system (TCCS) was established. It was found that approximately 40% of materials in the material library presented a loss of tabletability (i.e., Type I), 50% of materials had nearly unchanged tabletability (i.e., Type II), and 10% of materials suffered from increased tabletability (i.e., Type III). With the help of tensile strength (TS) vs. compression pressure curves implemented on both powders and granules, a data fusion method and the PLS2 algorithm were further applied to identify the differences in material properties requirements for direct compression (DC) and HSWGT. Results indicated that increasing the plasticity or porosity of the starting materials was beneficial to acquiring high TS of tablets made by HSWGT. In conclusion, the presented TCCS provided a means for the initial risk assessment of materials in tablet formulation design and the data modeling method helped to predict the impact of formulation ingredients on the strength of compacts.

Surface Modifiers on Composite Particles for Direct Compaction

Direct compaction (DC) is considered to be the most effective method of tablet production. However, only a small number of the active pharmaceutical ingredients (APIs) can be successfully manufactured into tablets using DC since most APIs lack adequate functional properties to meet DC requirements. The use of suitable modifiers and appropriate co-processing technologies can provide a promising approach for the preparation of composite particles with high functional properties. The purpose of this review is to provide an overview and classification of different modifiers and their multiple combinations that may improve API tableting properties or prepare composite excipients with appropriate co-processed technology, as well as discuss the corresponding modification mechanism. Moreover, it provides solutions for selecting appropriate modifiers and co-processing technologies to prepare composite particles with improved properties.

Improvements on multiple direct compaction properties of three powders prepared from Puerariae Lobatae Radix using surface and texture modification: comparison of microcrystalline cellulose and two nano-silicas

It has been reported that hydrophilic nano-silica (N) markedly improved direct compaction (DC) properties of Zingiberis Rhizoma alcoholic extract. This study aims to examine the broader scope and generality of the previous work by investigating (i) three powders, i.e., the directly pulverized product, ethanol extract, and water extract prepared from the same medicinal herb-Puerariae Lobatae Radix (named DP, EE, and WE) and (ii) the effects on their DC properties of co-processing with N, hydrophobic nano-silica (BN), or microcrystalline cellulose (C). Unexpectedly, C provided the best improvement on tabletability for WE, while N for both DP and EE. More importantly, only N could move all parent powders to a regime suitable for DC, and BN rather than C enabled parent WE to be directly compressed. Typically, 6/9 N-modified powders simultaneously met the requirements of DC on bulk density, flowability, and tablet tensile strength (σ_t). Principal component analysis indicated that DC properties were mainly governed by flowability and texture properties. The partial least-squares regression model revealed that flowability, texture parameters, and deformation behavior of powders were dominating factors impacting tablet σ_t and solid fraction. Overall, the findings are promising for the manufacture of high drug loading tablets of herbs by DC.

Pharmacotechnical Evaluation by SeDeM Expert System to Develop Orodispersible Tablets

Sediment delivery model (SeDeM) system is innovative tool to correlate micromeritic properties of powders with compressibility. It involves computation of indices which facilitate direct compressibility of solids and enable corrective measures through particle engineering. Study had multiple objectives, viz, (i) to enhance solubility of BCS class II, nevirapine using solid dispersions; (ii) SeDeM analyses of excipients and solid dispersions to analyze direct compressibility; and (iii) prepare orodispersible tablets (ODT). Solid dispersions were prepared by solvent evaporation. Superdisintegrants and solid dispersions were analyzed for primary indices of dimension, compressibility, flowability, stability, and disgregability derived from micromeritic properties. Radar diagrams were constructed to provide visual clues to deficient properties for direct compressibility. ODTs were prepared using excipients which passed criteria for direct compressibility and evaluated for tablet properties. Solid dispersions with Eudragit S100 revealed 6 to 10 fold increase in solubility in various dissolution media including biorelevant media in comparison with plain drug. Solubility was found to be pH dependent. SeDeM analyses facilitated identification of superdisintegrants and excipients with unfavorable compressibility. Radar diagrams provided a clear pictorial evidence of lacunae in powder properties. Based on SeDeM results, tablets were formulated by direct compression using crosspovidone, croscarmellose sodium, and mannitol. All batches showed 40% release in first minute in simulated salivary fluid.

Mathematical approaches for powders and multiparticulate units processability characterization in pharmaceutical development

An understanding of material properties and processing effects on solid dosage forms performance is required within the Quality-by-design approach to pharmaceutical development. Several research groups have developed mathematical approaches aiming to facilitate the selection of formulation composition and the manufacturing technology. These approaches are based on material particulate, bulk and compression-related properties. This paper provides theoretical assumptions and a critical review of different mathematical approaches for processability characterization of powders and multiparticulate units. Mathematical approaches have mainly been developed for directly compressible materials, but sometimes other manufacturing technologies, such as roller compaction and wet granulation, are also considered. The obtained compact tensile strength has been implemented in the majority of approaches, as an important characteristic describing compact mechanical properties. Flowability should be also evaluated, since it affects sample processability. Additionally, particle size and shape, material density and compressibility, compactibility and tabletability profiles have been also distinguished as relevant properties for solid dosage form development. The application of mathematical approaches may contribute to the mechanistic understanding of critical material attributes and facilitate dosage form development and optimization. However, it is essential to select the appropriate one, based on the intended dosage form characteristics, in order to ensure that all relevant powder/multiparticulate units characteristics are implemented and critically evaluated.

Formulation Study of a Co-Processed, Rice Starch-Based, All-in-One Excipient for Direct Compression Using the SeDeM-ODT Expert System

A co-processed, rice starch-based excipient (CS), previously developed and shown to exhibit good pharmaceutical properties, is investigated as an all-in-one excipient for direct compression (DC). An SeDeM-ODT expert system is applied to evaluate the formulation containing CS, in comparison with those containing the physical mixture and the commercial DC excipients. The results revealed that CS showed acceptable values in all six incidence factors of the SeDeM-ODT diagram. In addition, the comprehensive indices (IGC and IGCB) were higher than 5.0, which indicated that CS could be compressed with DC technique without additional blending with a disintegrant in tablet formulation. The formulation study suggested that CS can be diluted up to 60% in the formulation to compensate for unsatisfactory properties of paracetamol. At this percentage, CS-containing tablets exhibited narrow weight variation (1.5%), low friability (0.43%), acceptable drug content (98%), and rapid disintegration (10 s). The dissolution profile of CS displayed that more than 80% of the drug content was released within 2 min. The functionality of CS was comparable to that of high functionality excipient composite (HFEC), whereas other excipients were unsuccessful in formulating the tablets. These results indicated that CS was a suitable all-in-one excipient for application in DC of tablets.

Computational pharmaceutics - A new paradigm of drug delivery

In recent decades pharmaceutics and drug delivery have become increasingly critical in the pharmaceutical industry due to longer time, higher cost, and less productivity of new molecular entities (NMEs). However, current formulation development still relies on traditional trial-and-error experiments, which are time-consuming, costly, and unpredictable. With the exponential growth of computing capability and algorithms, in recent ten years, a new discipline named "computational pharmaceutics" integrates with big data, artificial intelligence, and multi-scale modeling techniques into pharmaceutics, which offered great potential to shift the paradigm of drug delivery. Computational pharmaceutics can provide multi-scale lenses to pharmaceutical scientists, revealing physical, chemical, mathematical, and data-driven details ranging across pre-formulation studies, formulation screening, in vivo prediction in the human body, and precision medicine in the clinic. The present paper provides a comprehensive and detailed review in all areas of computational pharmaceutics and "Pharma 4.0", including artificial intelligence and machine learning algorithms, molecular modeling, mathematical modeling, process simulation, and physiologically based pharmacokinetic (PBPK) modeling. We not only summarized the theories and progress of these technologies but also discussed the regulatory requirements, current challenges, and future perspectives in the area, such as talent training and a culture change in the future pharmaceutical industry.

Using a material database and data fusion method to accelerate the process model development of high shear wet granulation

High shear wet granulation (HSWG) has been wildly used in manufacturing of oral solid dosage (OSD) forms, and process modeling is vital to understanding and controlling this complex process. In this paper, data fusion and multivariate modeling technique were applied to develop a formulation-process-quality model for HSWG process. The HSWG experimental data from both literature and the authors' laboratory were fused into a single and formatted representation. A material database and material matching method were used to compensate the incomplete physical characterization of literature formulation materials, and dimensionless parameters were utilized to reconstruct process variables at different granulator scales. The exploratory study on input materials properties by principal component analysis (PCA) revealed that the formulation data collected from different articles generated a formulation library which was full of diversity. In prediction of the median granule size, the partial least squares (PLS) regression models derived from literature data only and a combination of literature data and laboratory data were compared. The results demonstrated that incorporating a small number of laboratory data into the multivariate calibration model could help significantly reduce the prediction error, especially at low level of liquid to solid ratio. The proposed data fusion methodology was beneficial to scientific development of HSWG formulation and process, with potential advantages of saving both experimental time and cost.

Comparison of the performance of two grades of metformin hydrochloride elaboration by means of the SeDeM system, compressibility, compactability, and process capability indices

Quality by design, applied to the development of a pharmaceutical drug, demands scientific methodologies, representing a source of information that will allow for a complete understanding the production process and the materials used for its manufacturing. Although the SeDeM system is a tool that enables a rational development of a product, result does not assure that an assessed material or mixture will be successful in terms of compression, hence, further research will be necessary on these features. The objective of this study was to assess and compare two grades of metformin hydrochloride elaboration: crystalline and direct compression using PXRD, the SeDeM expert system, the Heckel and Ryshkewitch-Duckworth models, as well as process control tools such as control charts and process capability indices to characterize and predict the performance of the materials in a direct compression process. The assessment identified that in spite of dealing with two different technical grades of a material with specific critical quality attributes for each one, PXRD analysis showed we dealt with the same crystalline structure, while the SeDeM system profiles obtained have very close values, and the main differences in materials were observed when subjecting them to conditions that simulate a compaction process with the Ryshkewitch-Duckworth model, in which a 46-times higher mechanical resistance was observed in the direct compression material compared with the crystalline one. The statistical control analysis revealed that only the direct compression material could be used to elaborate tablets whose weight variation was always maintained within the specification and control limits.

SeDeM Expert System, an Innovative Tool for Developing Directly Compressible Tablets: A Review

BACKGROUND

SeDeM (Sediment Delivery Model) expert system is a preformulation tool employed for evaluating direct compression suitability of various excipients. SeDeM is a 12 parameters derived diagram and SeDeM-ODT (Sediment Delivery Model-Orodispersible tablets) is a 15 parameters derived diagram that can be used as a research tool for reducing the product development time. The best possible excipients for a specified pharmaceutical active ingredient could be screened for direct compression suitability.

OBJECTIVE

SeDeM expert system has been successfully used and implemented for characterizing galenic properties of pharmaceutical excipients, direct compression suitability of excipients, development of ODT formulations, development of sustained-release formulations, and development of tablets of taste-masked drugs.

CONCLUSION

In the present review paper, the development and applications of SeDeM and SeDeMODT systems have been discussed in detail.

Using a Material Library to Understand the Impacts of Raw Material Properties on Ribbon Quality in Roll Compaction

The purpose of this study is to use a material library to investigate the effect of raw material properties on ribbon tensile strength (TS) and solid fraction (SF) in the roll compaction (RC) process. A total of 81 pharmaceutical materials, including 53 excipients and 28 natural product powders (NPPs), were characterized by 22 material descriptors and were compacted under five different hydraulic pressures. The transversal and longitudinal splitting behaviors of the ribbons were summarized. The TS-porosity and TS-pressure relationships were used to explain the roll compaction behavior of powdered materials. Through defining the target ribbon quality (i.e., 0.6 ≤ SF ≤ 0.8 and TS ≥ 1 MPa), the roll compaction behavior classification system (RCBCS) was built and 81 materials were classified into three categories. A total of 24 excipients and five NPPs were classified as Category I materials, which fulfilled the target ribbon quality and had less occurrence of transversal splitting. Moreover, the multivariate relationships between raw material descriptors, the hydraulic pressure and ribbon quality attributes were obtained by PLS regression. Four density-related material descriptors and the cohesion index were identified as critical material attributes (CMAs). The multi-objective design space summarizing the feasible material properties and operational region for the RC process were visualized. The RCBCS presented in this paper enables a formulator to perform the initial risk assessment of any new materials, and the data modeling method helps to predict the impact of formulation ingredients on strength and porosity of compacts.

A compression behavior classification system of pharmaceutical powders for accelerating direct compression tablet formulation design

In this paper, a compression behavior classification system (CBCS) for direct compression (DC) pharmaceutical powders is presented. Seven descriptors from a series of compression models for powder compressibility, compactibility and tabletability analysis were included in the CBCS. A new tabletability index d was proposed to differentiate three categories of tensile strength (TS) vs. pressure relationships, and its physical meaning was explained thoroughly. 130 materials containing diverse pharmaceutical excipients and natural product powders (NPPs) were fully characterized and were compiled into an in-house developed material library, in which 70 materials with potential DC applications were used to justify the effectiveness of the CBCS. Principle component analysis (PCA) was used to uncover the latent structure of compression variables. Moreover, partial least squares (PLS) regression models are established in prediction of both tablet TS and solid fraction (SF) based on the raw materials' physical characteristics, the compression behavior indices and the compression force. The obtained scores and loadings are used to group the materials and the compression variables, respectively. Different categories of tabletability for DC powders were clearly clustered along two orthogonal directions pointing to the index d and the compression force. Finally, a multi-objective design space was identified under the latent variable space, summarizing the operationally possible region for both material properties and compression pressure required in DC tablet formulation design.

Formulation development of medicated chewing gum tablets by direct compression using the SeDeM-Diagram-Expert-System

Medicated chewing gums represent an orally administered dosage form with promising potential for local and systemic drug delivery. However, compared to other solid oral dosage forms, formulation development and release mechanism of medicated chewing gums are extremely complex, and thus only few products reached the approval for the market so far. Therefore, Quality by Design (QbD) approaches for rational formulation development of medicated chewing gums are needed to utilize their full potential. For chewing gum tablets, which are manufactured by direct compression, QbD approaches derived from tableting processes might be exerted. In this context, the SeDeM-Diagram-Expert-System implements the QbD approach while indicating whether a blend is suitable for direct compression and comprises powder properties, which need to be improved to facilitate the formulation development. Here, we present the successful application of the SeDeM-Diagram-Expert-System to the formulation development of medicated chewing gum tablets manufactured by direct compression. Furthermore, limitations of the SeDeM-System for medicated chewing gum tablets are evaluated and potential modifications of the system are suggested and discussed for future use.

Benefits of Fractal Approaches in Solid Dosage Form Development

Pharmaceutical formulations are complex systems consisting of active pharmaceutical ingredient(s) and a number of excipients selected to provide the intended performance of the product. The understanding of materials' properties and technological processes is a requirement for building quality into pharmaceutical products. Such understanding is gained mostly from empirical correlations of material and process factors with quality attributes of the final product. However, it seems also important to gain knowledge based on mechanistic considerations. Promising is here to study morphological and/or topological characteristics of particles and their aggregates. These geometric aspects must be taken into account to better understand how product attributes emerge from raw materials, which includes, for example, mechanical tablet properties, disintegration or dissolution behavior. Regulatory agencies worldwide are promoting the use of physical models in pharmaceutics to design quality into a final product. This review deals with pharmaceutical applications of theoretical models, focusing on percolation theory, fractal, and multifractal geometry. The use of these so-called fractal approaches improves the understanding of different aspects in the development of solid dosage forms, for example by identifying critical drug and excipient concentrations, as well as to study effects of heterogeneity on dosage form performance. The aim is to link micro- and macrostructure to the emerging quality attributes of the pharmaceutical solid dosage forms as a strategy to enhance mechanistic understanding and to advance pharmaceutical development and manufacturing processes.

Raw Material Variability and Its Impact on the Online Adaptive Control of Cohesive Powder Blend Homogeneity Using NIR Spectroscopy

It is significant to analyze the blend homogeneity of cohesive powders during pharmaceutical manufacturing in order to provide the exact content of the active pharmaceutical ingredient (API) for each individual dose unit. In this paper, an online monitoring platform using an MEMS near infrared (NIR) sensor was designed to control the bin blending process of cohesive powders. The state of blend homogeneity was detected by an adaptive algorithm, which was calibration free. The online control procedures and algorithm’s parameters were fine-tuned through six pilot experiments and were successfully transferred to the industrial production. The reliability of homogeneity detection results was validated by 16 commercial scale experiments using 16 kinds of natural product powders (NPPs), respectively. Furthermore, 19 physical quality attributes of all NPPs and the excipient were fully characterized. The blending end time was used to denote the degree of difficulty of blending. The empirical relationships between variability of NPPs and the blending end time were captured by latent variable modeling. The critical material attributes (CMAs) affecting the blending process were identified as the particle shape and flowability descriptors of cohesive powders. Under the framework of quality by design (QbD) and process analytical technology (PAT), the online NIR spectroscopy together with the powder characterization facilitated a deeper understanding of the mixing process.