CELLETS® are pellets or spheres made of microcrystalline cellulose. The size ranges from 100 µm to 1400 µm. Being neutral starter cores, they can be used as carrier system for low-dosed APIs and allow diverse functional coating. See pellet technologies for a detailed description.
Electron microscopy yield perfect imaging data of the MCC pellets’ surfaces. Magnification: 250x, working distance 8.0 mm, voltage: 10 keV.
Available size classes are (click for more information):
Introduction to Multilayered Pharmaceutically Active Compound Technology
Multilayered pharmaceutically active compound-releasing microparticles in a liquid dosage form represent an innovative approach to oral drug delivery. This technology combines the benefits of coated pellets with the convenience of liquid administration. Effervescent tablets are solid dosage forms that release carbon dioxide when they dissolve in water. This reaction results from the interaction between an acid source, such as citric acid, and a carbonate or bicarbonate salt. Patients consume the resulting solution or suspension immediately after preparation. Consequently, effervescent tablets improve ease of administration and often enhance patient compliance.
Pellets play an increasingly important role in modern effervescent tablet formulations. Unlike conventional powder blends, pellets can carry individual functional coatings that protect active pharmaceutical ingredients (APIs) from degradation. In addition, pellets can separate incompatible ingredients within the same dosage form. They also improve taste masking and enable modified-release properties. As a result, formulators can develop more stable and effective products. Furthermore, pellet-containing effervescent tablets often reduce gastrointestinal irritation and improve dose uniformity. These advantages benefit both the final pharmaceutical product and the patient.
Multilayered pharmaceutically active compound-large
Summary of EP3117824A1
The European patent EP3117824A1 describes a drug delivery platform based on multilayered pharmaceutically active compound-releasing microparticles suspended in a liquid dosage form. The invention addresses a major challenge in pharmaceutical formulation. Many controlled-release and enteric-coated particles lose functionality when they remain in contact with water for extended periods. Therefore, maintaining stability during storage becomes difficult.
The patented technology uses microparticles that contain an API-loaded core surrounded by multiple functional coating layers. A controlled-release or enteric coating forms the intermediate layer. An additional outer protective layer surrounds this coating. The inventors designed this outer layer from a combination of hydrophilic and hydrophobic materials. Consequently, the layer protects the underlying release-controlling membrane from premature exposure to the liquid environment.
During storage, the protective coating minimizes drug leakage and preserves the integrity of the controlled-release system. As a result, the microparticles maintain their desired release characteristics for extended periods. Once the patient administers the formulation, the outer coating dissolves rapidly in the stomach. Subsequently, the underlying controlled-release coating resumes its intended function. This mechanism allows the formulation to deliver the API at a predefined location or rate within the gastrointestinal tract.
The invention offers particular advantages for drugs that require modified release, intestinal targeting, or protection from acidic gastric conditions. In addition, the technology supports the development of patient-friendly liquid formulations. This feature benefits pediatric, geriatric, and dysphagic patients who often struggle to swallow tablets or capsules. Overall, the patent combines the flexibility of pellet-based drug delivery with improved stability in aqueous dosage forms. Therefore, it represents an important advancement in oral pharmaceutical technology.
Impact of MCC spheres in this Patent
In EP3117824A1, CELLETS® or similar spherical starter cores serve as the fundamental substrate for producing the multilayered pharmaceutically active compound-releasing microparticles. These inert pellet cores, commonly composed of microcrystalline cellulose, provide a highly uniform and mechanically stable surface onto which drug-containing layers and subsequent functional coatings can be applied with high precision.
Their excellent sphericity promotes uniform coating thickness, which is critical for achieving reproducible controlled-release performance and minimizing variability between pellets. Furthermore, Cellets enable high drug loading while maintaining robust processing characteristics during fluid-bed coating operations.
Pellet size also plays an important role in the final product performance. Smaller pellets, typically in the range of 100–500 µm (such as CELLETS® 100, 200, 350), offer a larger surface area and can provide faster or more uniform drug release, whereas larger pellets, often between 500–1500 µm (such as CELLETS® 500, 700, 1000), facilitate the application of multiple coating layers and may support more sophisticated release profiles.
In addition, smaller pellets generally improve content uniformity and patient acceptability, especially in liquid and effervescent dosage forms, because they create a smoother mouthfeel and more homogeneous suspension. Therefore, selecting the appropriate Cellet size represents a key formulation parameter that influences coating efficiency, drug release kinetics, stability, and overall patient experience.
Acetylsalicylic Acid, Paracetamol, and Ascorbic Acid in Pellet-Based Effervescent Formulations
Although EP3117824A1 does not specifically focus on acetylsalicylic acid, paracetamol, or ascorbic acid, the technology applies well to these APIs. Acetylsalicylic acid, commonly known as aspirin, belongs to the nonsteroidal anti-inflammatory drug (NSAID) class. It treats pain, fever, inflammation, and cardiovascular disorders. Depending on the classification source and physiological conditions, aspirin generally falls within BCS Class I or Class III. Because aspirin can irritate the gastric mucosa, pellet-based controlled-release systems may improve gastrointestinal tolerability.
Paracetamol is an analgesic and antipyretic agent that treats pain and fever. It is generally classified as a BCS Class I compound due to its high solubility and permeability. Furthermore, pellet technology can improve taste masking and provide modified-release options. These properties make paracetamol formulations more suitable for pediatric and elderly patients.
Ascorbic acid, also known as vitamin C, functions as a water-soluble vitamin and antioxidant. Healthcare professionals use it to prevent and treat vitamin C deficiency. It exhibits high aqueous solubility and frequently appears in effervescent products. Moreover, pelletization can improve formulation stability by separating ascorbic acid from reactive ingredients. This approach may reduce degradation during storage and improve product quality.
Conclusion and Outlook
Multilayered pharmaceutically active compound technology offers a sophisticated solution for modern oral drug delivery. It combines coated pellet systems with liquid dosage forms while maintaining controlled-release functionality. Moreover, the technology supports improved stability, enhanced patient convenience, and flexible formulation design. When formulators incorporate pellets into effervescent tablets, they can protect sensitive APIs, reduce gastrointestinal side effects, and optimize therapeutic performance. As pharmaceutical research advances, multilayered pharmaceutically active compound systems will likely support more complex formulations and personalized treatment strategies. Consequently, this technology may become an increasingly important platform for next-generation oral medicines.
Patent Summary
Name of Patent: Multilayered pharmaceutically active compound-releasing microparticles in a liquid dosage form
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Introduction to the Formulation and Design of Multiunit Particulate Systems
Formulation and design of multiunit particulate systems focus on oral dosage forms that contain many small, functional subunits instead of one single unit. These systems typically consist of pellets, granules, or coated spheres that are filled into capsules or compressed into tablets. As a result, they allow precise control of drug release and improved robustness during gastrointestinal transit. Moreover, the formulation and design of multiunit particulate systems emphasize a deep understanding of materials, coating technologies, and compression behavior. Therefore, developers can protect sensitive drug layers while ensuring consistent performance. In recent years, Quality by Design approaches have further strengthened this concept by linking formulation variables directly to product quality and clinical relevance.
Functionality and Consumer Compliance Opportunities of Multiunit Particulate Systems
Multiunit particulate systems offer clear functional advantages that directly support consumer compliance. First, the multiparticulate structure distributes the drug dose along the gastrointestinal tract, which improves absorption consistency. In addition, this distribution reduces local irritation and lowers the clinical risk of dose dumping. Furthermore, these systems often improve swallowability because the individual subunits are small and well tolerated. Consequently, patient groups such as children and older adults benefit significantly. At the same time, multiunit particulate systems enable flexible dosing and advanced release profiles. Therefore, they align better with daily routines and long-term treatment needs, which ultimately enhances adherence.
Formulation and Design of Multiunit Particulate Systems
Summary of the Pantoprazole MUPS Tablet Study
The referenced publication examines the formulation and design of multiunit particulate systems (MUPS) through the development of a pantoprazole MUPS tablet using a Quality by Design framework. The study aimed to understand how selected formulation variables affect critical tablet characteristics. To achieve this, the authors used enteric-coated pantoprazole pellets as multiparticulate units and compressed them into tablets with protective excipients. As a result, the formulation needed to balance mechanical strength with coating integrity.
The researchers applied a factorial design of experiments to evaluate three key variables: dry polymer content, matrix-forming polymer concentration, and pellet loading. Subsequently, they measured responses such as dissolution behavior, tablet hardness, friability, and disintegration time. The results showed that each variable influenced tablet quality in a measurable way. For example, higher pellet content increased the risk of coating damage during compression. However, appropriate polymer levels reduced this risk and stabilized drug release.
Based on statistical analysis, the study defined an optimized design space that delivered robust tablets with acceptable mechanical properties. In addition, the optimized formulation demonstrated dissolution behavior comparable to a marketed reference product. Therefore, the study confirmed that a well-designed multiunit particulate system can deliver pantoprazole effectively without compromising enteric protection. Overall, the work highlights how systematic formulation control improves both product performance and development efficiency.
Role of MCC Spheres in the Multiunit Particulate System
MCC spheres (such as CELLETS® 150-300) played a central role as inert starter cores in the multiparticulate formulation. First, they provided a uniform and mechanically stable substrate for drug layering. Moreover, their spherical shape supported homogeneous coating and predictable dissolution behavior. During compression, MCC spheres showed favorable plastic deformation, which helped absorb mechanical stress. As a result, they protected the enteric coating from cracking or rupture. Consequently, MCC spheres enabled the successful conversion of coated pellets into a compressed MUPS tablet while maintaining functional integrity.
Conclusion and Outlook
In conclusion, formulation and design of multiunit particulate systems offer a robust strategy for developing patient-friendly oral dosage forms. The pantoprazole study clearly demonstrates how a Quality by Design approach links formulation variables to tablet performance. Moreover, the use of MCC spheres highlights the importance of selecting suitable core materials for compression stability. Looking ahead, advances in material science and process understanding will further strengthen multiunit particulate systems. Therefore, these systems will continue to play a key role in improving therapeutic consistency and consumer compliance.
References
[1] G.S. Sonar, S. Rawat, International Journal of PharmTech Research, CODEN (USA): IJPRIF, ISSN: 0974-4304, Vol.8, No.8, pp 05-23, 2015. (link)
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Influence of Water on the Structure of MCC describes how moisture reshapes microcrystalline cellulose at both structural and dielectric levels [1]. Water interacts strongly with hydroxyl groups on cellulose chains. Therefore, it changes hydrogen bonding and mobility inside amorphous and crystalline regions. Moreover, the system develops distinct hydration states depending on water content. At low moisture levels, water remains mostly adsorbed on surfaces. However, at higher levels, it forms multilayer hydration shells around crystallites. Consequently, the material shows measurable changes in crystallite order and dielectric relaxation behavior. In addition, a critical hydration threshold appears where the structure shifts toward a continuous interfacial water network. As a result, both permittivity and loss mechanisms change significantly across temperature and frequency ranges.
Technologies and Materials Used in the Study
The study combines structural and dielectric characterization techniques to analyze hydrated cellulose systems. Specifically, X-ray diffraction resolves changes in crystallinity and crystallite dimensions. In addition, thermal analysis distinguishes bound water from loosely adsorbed water fractions. Broadband dielectric spectroscopy then tracks relaxation processes across temperature and frequency domains. Therefore, the researchers connect molecular mobility with macroscopic dielectric response.
The material system consists of microcrystalline cellulose processed into compacted pellets for measurement. Moreover, pellet compaction ensures stable geometry and reproducible dielectric contact. In similar experimental frameworks, standardized spherical MCC pellets such as CELLETS® 1000 are often used. These pellets provide uniform particle size, consistent porosity, and predictable packing behavior. Consequently, they reduce structural variability during pressing. In addition, they improve signal stability in dielectric spectroscopy because they minimize air gaps and heterogeneity effects. As a result, researchers can isolate water-induced changes more reliably and compare hydration states under controlled conditions.
Influence of Water on Structure and Dielectric Behavior
Water strongly controls both structure and dielectric response in MCC. Initially, small water amounts occupy surface sites and weak adsorption layers. However, increasing hydration strengthens hydrogen bonding rearrangements. Moreover, water molecules increase chain mobility in amorphous regions. Consequently, the material shows shifts in crystallite boundary structure and apparent crystallinity.
At moderate hydration, water forms multilayer shells around crystallites. Therefore, interfacial polarization becomes more pronounced. In addition, dielectric permittivity increases due to enhanced dipole alignment. Meanwhile, relaxation processes shift toward lower temperatures because water lowers activation barriers for molecular motion. As a result, β-relaxation associated with surface groups becomes more visible.
At higher hydration levels, the system approaches a percolated water network. Thus, the dielectric response becomes dominated by interfacial water dynamics. Moreover, the cellulose–water system transitions into a more flexible structural regime. Consequently, both structural stability and dielectric dispersion change significantly across frequency ranges.
Conclusion and Outlook
Water governs the structural and dielectric behavior of MCC in a direct and measurable way. Specifically, it modifies hydrogen bonding networks and reorganizes interfacial regions. Therefore, hydration controls crystallite order and molecular mobility at the same time. Moreover, a critical moisture threshold marks a transition into a continuous hydration regime.
In addition, these findings highlight the importance of controlled humidity in cellulose-based systems. Future research should focus on tuning water content to engineer dielectric properties. Moreover, standardized pellet systems, including CELLETS 1000-type MCC materials in comparable studies, can improve reproducibility. Consequently, hydrated cellulose systems may support future applications in bio-based dielectrics, sensors, and adaptive functional materials.
References
[1] Kovalov, K.M., Alekseev, O.M., Lazarenko, M.M. et al. Influence of Water on the Structure and Dielectric Properties of the Microcrystalline and Nano-Cellulose. Nanoscale Res Lett12, 468 (2017); doi: 10.1186/s11671-017-2231-5
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MCC pellets under rheological investigation are ideal model spheres for studying powder behavior. In this study, we revisit the work of V. Mohylyuk and R. Dattani to analyze the effect of pellet size on powder properties. Understanding how pellet size influences flow and handling is essential for optimizing powder performance. Moreover, investigating size variations helps improve material processing and formulation strategies. By focusing on these aspects, researchers can better predict and control the behavior of MCC spheres in different applications.
Rheological behavior has a deep impact
The rheological behavior of powders greatly affects pharmaceutical formulations and processing steps. In particular, when studying MCC pellets under rheological investigation, powder rheology becomes a key area of focus. Typically, powders behave as solids under static conditions; however, they can fluidize under certain circumstances. Consequently, fluidization is widely used in pharmaceutical processes because it enables controlled and uniform coating or layering of starter beads with drugs and functional excipients. Moreover, while fluid behavior in liquids depends on inter- and intra-molecular interactions, network bonds, and temperature, powder fluidization primarily relies on micro-particular properties such as particle size, surface characteristics, and flowability. In addition, the exact gas speed and volume required for powder fluidization must be carefully adjusted for each system. Therefore, a thorough analysis of the powder is essential to achieve precise control and optimal performance.
In this study, CELLETS® are used for the investigation. These pellets consist of Microcrystalline Cellulose, featuring a smooth surface, high sphericity, and minimal friability. Due to these properties, CELLETS® are popular as starter beads in pharmaceutical formulations and are ideal model spheres for rheological studies. Four types—CELLETS® 90, CELLETS® 100, CELLETS® 200, and CELLETS® 350—were examined, with size distributions ranging from 90 µm to 500 µm. The D50 values for these types vary between 94 µm and 424 µm. The specific size distribution of each CELLETS® type is summarized in Table 1.
Table 1: Particle size distribution of selected MCC spheres.
Characterization Methods for MCC Pellets Under Rheological Investigation
First, we measured the particle size distribution of MCC pellets under rheological investigation using optical digital microscopy (Keyence VHX 600). This approach provides precise and reliable data on pellet dimensions, which is essential for understanding their flow and handling properties.
Next, we applied standard pharmacopoeia methods to determine bulk and tapped density, as well as flow rate using a gravitational funnel. In addition, we analyzed the dynamic angle of repose and dynamic cohesivity index with a rotating drum tester (GranuDrum). Furthermore, we used a powder rheometer (FT4 Powder Rheometer) to evaluate basic flowability energy, specific energy, aerated energy, permeability, and compressibility. Altogether, these measurements give a comprehensive understanding of MCC pellets under rheological investigation and offer detailed insights into their performance in pharmaceutical applications.
Results of the rheological investigations
Figure 1 presents the particle size distribution of MCC pellets under rheological investigation, as measured with an optical digital microscope.
With increasing particle size the apparent specific surface area (fig. 2) decreases obviously. Hence, a decrease in pellet size, allow an expectation in increase in mechanical interlocking.
With increasing particle size, the bulk and tapped density of CELLETS® increases; however, the densification kinetics remained approximately the same for all pellet sizes (Fig. 3). Moreover, a few periodic oscillations significantly influenced the density of the pellets, highlighting subtle variations in their behavior.
With increasing particle size the compressibility decreases (fig. 4). The applied force was identical for all pellets sizes. Worsening packing efficiency.
With increasing particle size the permeability increases while applying the same force for all pellet types. (fig. 5). increase in voids between particles.
The gravitational funnel method suggests an absence of correlation between the mass flow rate and pellet size or specific surface area (fig. 6).
Analyzing the dynamic angle of repose
We analyzed the dynamic angle of repose to evaluate the powder flow of MCC pellets under rheological investigation. All pellet sizes showed similar behavior: as the rotation speed increased, the angle of repose rose almost linearly. The measurements for all pellet types formed a funnel shape within the range of analytic errors (Fig. 7). These results clearly characterize the dynamic flow ability of the powders.
With increasing particle size the specific energy decreases (fig. 8). The level of interlocking and friction between powder particles decreased, the flowability increased.
With increasing particle size the basic flowability energy decreases (fig. 9). the flowability in a constrained environment increased.
The aerated energy rises as air velocity decreases (Fig. 10). This parameter helps determine the minimum fluidization velocity, as increasing air velocity alters interparticle interactions.
The aerated energy increased with increasing pellet size (fig. 11). dependent on particle mass and inter-particle interactions (friction).
with increasing pellet size, the cohesive index decreases (fig. 12). an indicator of the sum of inter-particle interaction forces.
Summary
Overall, researchers have now characterized MCC pellets under rheological investigation more comprehensively than ever before, providing new insights into their flow behavior and material properties. Powder rheology methods successfully revealed the bulk powder behavior, flow properties, and inter-particular interactions as a function of pellet size. CELLETS® served as robust model spheres made of Microcrystalline Cellulose, making them ideal for these detailed investigations. This study highlights the importance of pellet size in predicting and optimizing powder performance in pharmaceutical formulations.
References
[1] V. Mohylyuk and R. Dattani, “Assessment of the effect of microcrystalline cellulose (MCC) spheres size on the flow via powder rheology”, Conference: The FORGE: Hybrid Conference on Particle Characterisation (March 2022), doi:10.13140/RG.2.2.14935.75688
Research Advances in MCC Pellet Technology and Applications
Scientific literature on MCC pellets highlights the growing importance of CELLETS® in pharmaceutical and scientific research. These microcrystalline cellulose spheres play a key role in developing reliable multiparticulate drug delivery systems. Researchers have investigated improved rivaroxaban dissolution, efficient film coating kinetics, and their use in orally disintegrating films. In addition, studies focus on colon-targeted vitamin B₂ release and fluidized-bed coating performance. Moreover, academic theses explore uniform hot-melt coating techniques and detailed modeling of tablet disintegration. As a result, MCC pellets continue to prove their versatility across many dosage forms. Consequently, this expanding body of literature reinforces the value of CELLETS® in advancing modern drug delivery technologies.
Selected Scientific literature on MCC pellets
Please, find scientific literature on MCC pellets (CELLETS®), MCC spheres. This list is constantly updated and does not claim to be complete. If you are author, scientist or R&D specialist, please submit your present publication to us for improving the visibility.
Research article Optimising the in vitro and in vivo performance of oral cocrystal formulations via spray coating European Journal of Pharmaceutics and Biopharmaceutics, Volume 124, March 2018, Pages 13-27
Dolores R. Serrano, David Walsh, Peter O’Connell, Naila A. Mugheirbi, Zelalem Ayenew Worku, Francisco Bolas-Fernandez, Carolina Galiana, Maria Auxiliadora Dea-Ayuela, Anne Marie Healy
Conference abstract Multiple-unit orodispersible mini-tablets International Journal of Pharmaceutics, Volume 511, Issue 2, 25 September 2016, Page 1128
Anna Kira Adam, Christian Zimmer, Stefan Rauscher, Jörg Breitkreutz
Research article Asymmetric distribution in twin screw granulation European Journal of Pharmaceutics and Biopharmaceutics, Volume 106, September 2016, Pages 50-58
Tim Chan Seem, Neil A. Rowson, Ian Gabbott, Marcelde Matas, Gavin K. Reynolds, AndyIngram
Research article Physical properties of pharmaceutical pellets Chemical Engineering Science, Volume 86, 4 February 2013, Pages 50-60
Rok Šibanc, Teja Kitak, Biljana Govedarica, StankoSrčič Rok Dreu
Research article Understanding Fluidized-Bed Granulation Pharmaceutical Technology 35 (8), 2011, 63-67 A. Burggraeve, T. Van Den Kerkhof, M. Hellings, J.P. Remon, C. Vervaet, T. De Beer
Research article Labscale fluidized bed granulator instrumented with non-invasive process monitoring devices Chemical Engineering Journal, Volume 164, Issues 2–3, 1 November 2010, Pages 268-274
Jari T. T. Leskinen, Matti-Antero H. Okkonen, Maunu M. Toiviainen, Sami Poutiainen, Mari Tenhunen, Pekka Teppola, Reijo Lappalainen, Jarkko Ketolainen, Kristiina Järvinen
Research article New insights into segregation during tabletting International Journal of Pharmaceutics, Volume 397, Issues 1–2, 15 September 2010, Pages 19-26
S. Lakio, S. Siiriä, H. Räikkönen, S. Airaksinen, T. Närvänen, O. Antikainen, J.Yliruusi
Research article Granule size distribution of tablets Journal of Pharmaceutical Sciences, Volume 99, Issue 4, April 2010, Pages 2061-2069
Satu Virtanen, Osmo Antikainen, Heikki Räikkönen, Jouko Yliruusi
Research article In vivo evaluation of the vaginal distribution and retention of a multi-particulate pellet formulation European Journal of Pharmaceutics and Biopharmaceutics, Volume 73, Issue 2, October 2009, Pages 280-284
Nele Poelvoorde, Hans Verstraelen, Rita Verhelst, Bart Saerens, Ellen De Backer, Guido Lopes dos Santos Santiago, Chris Vervaet, Mario Vaneechoutte, Fabienne De Boeck, Luc Van Borteld, Marleen Temmerman, Jean-Paul Remon
List – Publications with MCC spheres, 2008 and earlier
Research article Attrition strength of different coated agglomerates Chemical Engineering Science, Volume 63, Issue 5, March 2008, Pages 1361-1369
B. van Laarhoven, S.C.A. Wiers, S.H. Schaafsma, G.M.H. Meesters
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Introduction to delayed release oral pharmaceutical compositions
Delayed release oral pharmaceutical compositions enable drug delivery at a defined time after oral administration. Unlike immediate release dosage forms, these systems control when the active pharmaceutical ingredient becomes available for absorption. As a result, they protect acid-sensitive drugs and allow targeted delivery to specific gastrointestinal regions. Moreover, delayed release forms can reduce gastric irritation and peak-related side effects. Therefore, they often improve patient tolerance and adherence. From a consumer compliance perspective, these formulations support simplified dosing schedules and more predictable therapeutic effects. Consequently, they play a key role in chronic therapies that demand long-term adherence and consistent drug exposure.
Summary of US12521351B1: delayed release oral pharmaceutical compositions
The patent US12521351B1 describes delayed release oral pharmaceutical compositions designed primarily for treating inflammatory bowel disease. Specifically, the invention focuses on multiparticulate systems containing mesalamine and hyaluronan within an oral capsule. These particles use an inert core that serves as a substrate for successive functional layers. First, a mesalamine-containing drug layer is applied. Next, a hyaluronan layer follows, which contributes both therapeutic and release-modifying functions. Finally, an outer coating controls the onset of drug release in the gastrointestinal tract.
Importantly, the patent emphasizes controlled release timing rather than simple gastro-resistance. The coating system delays drug exposure until the dosage form reaches intestinal regions associated with inflammation. As a result, the formulation minimizes drug loss in the stomach and improves local efficacy. Furthermore, the multiparticulate design allows uniform drug distribution throughout the intestine, which reduces variability in drug exposure.
In addition, the patent outlines manufacturing methods such as fluid-bed coating and encapsulation. These processes ensure reproducible layer thickness and particle size distribution. Consequently, the formulations achieve consistent dissolution behavior across batches. The patent also defines preferred ranges for core size, drug load, and coating thickness. Therefore, it provides a framework for scalable industrial production.
Overall, US12521351B1 demonstrates how delayed release oral pharmaceutical compositions can combine therapeutic targeting with patient-friendly oral delivery. By integrating functional excipients and structured layering, the invention advances existing mesalamine therapies toward improved clinical performance.
Technical considerations and formulation context
Delayed release oral drug forms differ fundamentally from uncontrolled release systems. While immediate release products dissolve rapidly after ingestion, delayed release formulations intentionally suppress early dissolution. Consequently, they reduce exposure in the stomach and shift drug availability to later intestinal segments. This distinction becomes critical for drugs that cause gastric irritation or degrade in acidic environments.
Dissolution profiles represent a central design parameter. Ideally, delayed release systems show minimal drug release under acidic conditions. Then, they exhibit a rapid and reproducible release once intestinal pH thresholds are reached. Therefore, formulators must carefully balance coating composition, thickness, and particle size. In addition, variability in gastrointestinal transit times must be considered during development.
However, delayed release formulations face several obstacles. Uniform coating of multiparticulates remains technically demanding. Moreover, small variations in process parameters can significantly affect release kinetics. Stability during storage also presents challenges, especially for moisture-sensitive coatings. As a result, robust process control and extensive dissolution testing are essential.
Within this patent context, CELLETS® 500 play a supportive yet important role. These microcrystalline cellulose starter cores provide a smooth, inert, and size-defined substrate. Consequently, they enable uniform drug layering and coating application. Their narrow particle size distribution improves batch reproducibility and dissolution consistency. Therefore, CELLETS® 500 contribute directly to the functional reliability of delayed release oral pharmaceutical compositions.
Conclusion and outlook
Delayed release oral pharmaceutical compositions continue to shape modern oral drug delivery. They align pharmacokinetics with disease physiology and patient needs. The US12521351B1 patent illustrates how structured multiparticulate systems can enhance intestinal targeting and therapeutic consistency. Looking ahead, advances in coating polymers, starter core technologies, and process analytics will further refine these formulations. Consequently, delayed release oral pharmaceutical compositions will remain central to improving efficacy, safety, and long-term patient compliance in oral therapies.
Patent Summary
Name of Patent: Delayed release oral pharmaceutical composition
Chewable formulations with MCC starter cores: Patient-centric design and pharmaceutical relevance
Chewable formulations with MCC starter cores are an advanced oral dosage form that combines patient-friendly administration with robust pharmaceutical performance. Thereby, patient refers includes humans and non-human mammalian animals, such as dogs, cats, mice, rats, guinea pigs, rabbits, ferrets, cows, horses, sheep, goats, and pigs. At the outset, these formulations address a key challenge in drug therapy, namely patient compliance, by offering a dosage form that patients can chew without water. Consequently, they are particularly suitable for pediatric, geriatric, and veterinary applications. Moreover, chewable dosage forms allow formulators to improve taste, mouthfeel, and ease of use, which directly supports adherence to therapy. At the same time, MCC starter cores provide excellent mechanical stability, uniformity, and processing reliability. Therefore, they enable consistent drug loading, predictable disintegration, and scalable manufacturing. As a result, this combination creates significant opportunities for modern, patient-centric drug delivery.
Chewable formulations with MCC starter cores according to WO2022049149A1
The patent WO2022049149A1 describes chewable pharmaceutical compositions designed to disintegrate rapidly while maintaining acceptable texture and stability. In particular, the invention focuses on soft chewable dosage forms that contain at least one active pharmaceutical ingredient together with carbonate or bicarbonate compounds that act as efficient disintegrants. As a result, the dosage form breaks down quickly when exposed to aqueous or gastric media. This rapid disintegration directly supports fast and reproducible dissolution of the API. Furthermore, the patent emphasizes that surface structure, porosity, and wettability of the chewable matrix strongly influence drug release. Therefore, careful control of formulation and processing parameters becomes essential. The disclosed chewable products typically achieve disintegration within pharmacopeial limits and release a high proportion of the API within short dissolution times. In addition, the patent highlights the importance of balancing lipophilic excipients, since excessive hydrophobicity can delay disintegration. Consequently, the invention aims to deliver chewable dosage forms that combine good palatability with reliable pharmaceutical performance. Overall, the patent demonstrates how optimized excipient systems can overcome common limitations of chewable drugs while improving patient acceptance.
Chewable formulations with MCC starter cores
Advances, dissolution considerations, and API challenges in chewable dosage forms
Chewable formulations with MCC starter cores illustrate clear advances in chewable drug technology. First, the use of spherical MCC cores supports multiparticulate designs that improve content uniformity and process robustness. Moreover, these cores enable precise API layering, which enhances dose accuracy and reproducibility. When considering dissolution profiles, formulators must carefully manage core porosity, disintegrant efficiency, and wettability. Therefore, rapid liquid penetration and controlled matrix breakdown remain critical success factors. At the same time, APIs in chewable formulations face both obstacles and opportunities. On one hand, taste masking, stability, and dissolution control present technical challenges. On the other hand, chewable formats open new possibilities for poorly compliant patient groups and combination therapies. Consequently, successful products require a well-balanced formulation strategy that aligns API properties with excipient functionality.
Role of CELLETS® in the context of this patent
Although WO2022049149A1 does not explicitly name commercial products, its technical concept strongly aligns with MCC starter cores such as CELLETS® 100 (100-200 µm) and CELLETS® 200 (200-355 µm). These microcrystalline cellulose spheres offer high sphericity, low friability, and narrow particle size distribution. Therefore, they provide an ideal substrate for API layering in chewable multiparticulate systems. CELLETS® 100 and CELLETS® 200 support uniform coating, predictable dissolution behavior, and efficient processing in fluidized bed systems. In addition, their inert and tasteless nature helps minimize interactions with APIs and flavoring agents. As a result, they play a crucial functional role in achieving stable, reproducible, and patient-acceptable chewable formulations.
Conclusion and outlook for chewable formulations with MCC starter cores
Chewable formulations with MCC starter cores represent a strategic convergence of patient-centric design and pharmaceutical engineering. In conclusion, the integration of MCC starter cores enhances manufacturing reliability, dose uniformity, and dissolution performance while supporting improved patient compliance. Moreover, patents such as WO2022049149A1 demonstrate how modern excipient systems can overcome traditional limitations of chewable dosage forms. Looking ahead, further innovation will likely focus on advanced taste-masking technologies, tailored dissolution profiles, and broader API compatibility. Therefore, chewable formulations with MCC starter cores are well positioned to play an increasingly important role in future oral drug delivery.
Introduction to soft tabletting of pellets and MCC pellet functionality
Soft tabletting of pellets is a specialized pharmaceutical compaction approach that enables the compression of coated pellet subunits into tablets while preserving pellet integrity and drug release performance. In this context, Multiple Unit Pellet Systems, or MUPS, combine the biopharmaceutical advantages of multiparticulates with the handling and patient benefits of tablets. MCC-based pellets play a central role in this technology because they deform plastically, cushion mechanical stress, and maintain coating functionality during compression. As a result, MCC pellets support robust tabletting, rapid tablet disintegration, and reliable dissolution behavior. Moreover, MUPS tablets reduce dose dumping risk, improve gastrointestinal distribution, and enhance patient compliance compared to conventional single-unit tablets. Consequently, soft tabletting of pellets has become a preferred strategy for modified-release, delayed-release, and combination products where performance consistency matters.
Summary of the publication on soft tabletting of pellets
The referenced publication investigates soft tabletting of pellets using MCC 102 and UICEL-A/102 as key pellet-forming and cushioning materials. The research focuses on producing MUPS tablets that achieve sufficient mechanical strength while preserving the original dissolution profile of coated pellets. Therefore, the work examines how pellet composition, morphology, and compaction behavior interact during tabletting.
The study uses sodium diclofenac as a model drug and applies a sustained-release polymer coating to the pellets. Both homogeneous pellets, produced by extrusion–spheronization, and inhomogeneous pellets, produced by dry powder layering on inert cores, were evaluated. As a result, the work provides insight into how pellet structure affects deformation and coating integrity during compression.
MCC 102 pellets demonstrated strong plastic deformation, which enabled softer compaction and better preservation of pellet structure. In contrast, UICEL-A/102 pellets showed higher porosity and swelling capacity. Consequently, UICEL-A/102-based MUPS disintegrated faster and released the drug more rapidly. However, this same swelling behavior limited their suitability for sustained-release applications.
When used in MUPS tablets, MCC 102 pellets achieved crushing strengths between 70 and 100 N while still disintegrating rapidly. Therefore, these tablets closely matched the dissolution behavior of uncompressed pellets. UICEL-A/102 pellets also formed mechanically stable tablets, but their higher swelling led to faster disintegration and altered release kinetics.
The study further highlights the importance of pellet production method. Inhomogeneous pellets layered onto inert starter cores responded differently to compression than homogeneous pellets. Notably, MCC-based starter cores supported softer tabletting and reduced coating damage. In contrast, sugar-based cores increased compaction stress and slowed tablet disintegration. Thus, the choice of core material directly influenced MUPS performance.
Overall, the publication demonstrates that successful soft tabletting of pellets requires careful alignment of pellet material, structure, and compaction parameters. Otherwise, coating damage or delayed disintegration may compromise therapeutic performance.
Role of Cellets, key insights, and material-related effects
In this publication, Cellets function as MCC-based inert starter cores for dry powder layering. Therefore, they provide a plastically deformable substrate that absorbs compression forces during tabletting. As a result, pellets layered onto Cellets show improved coating integrity and more predictable dissolution behavior compared to sugar-based cores.
The most important take-home message is that pellet material properties govern MUPS performance more than tablet hardness alone. Specifically, MCC 102 offers a balanced profile for sustained-release MUPS, whereas UICEL-A/102 favors immediate-release systems. Consequently, formulation goals should guide cellulose selection early in development.
Obstacles for MCC pellets include managing excessive densification during compression and controlling disintegration time. However, opportunities exist in tailoring MCC pellet porosity, size distribution, and deformation behavior. Advanced Cellets grades may further optimize cushioning and release stability.
Pellet sphericity improves flowability and die filling, which enhances tablet uniformity. At the same time, low friability limits coating damage and fines generation. Hardness requires precise adjustment, because excessive hardness delays disintegration, while insufficient hardness weakens tablets. Therefore, balancing these parameters remains critical for reliable soft tabletting of pellets.
Conclusion and outlook
Soft tabletting of pellets enables advanced MUPS dosage forms that combine multiparticulate performance with tablet convenience. This publication clearly shows that MCC pellets, especially Cellets, support soft compaction and stable drug release when formulation parameters align with material behavior. Although challenges remain, ongoing improvements in pellet engineering and MCC excipient design will expand MUPS applications. In the future, predictive formulation strategies and optimized MCC pellets will further strengthen soft tabletting of pellets as a core pharmaceutical technology.
https://cellets.com/wp-content/uploads/2026/01/Soft-tabletting-of-pellets-Cellets-small.jpg451601Bastian Arlthttps://cellets.com/wp-content/uploads/2016/10/Logo_Cellets_2016_website.pngBastian Arlt2026-03-16 19:31:232026-03-16 19:31:23Soft tabletting of pellets into Multiple Unit Pellet Systems (MUPS)
Introduction to Particle Size Distributions of Inert Spheres and Their Role in Pelletized Pharmaceutical Products
In pharmaceutical formulation science, Particle Size Distributions of Inert Spheres represent a fundamental quality attribute for multiparticulate dosage forms. Inert spheres, such as microcrystalline cellulose pellets, act as neutral carriers for active pharmaceutical ingredients. They enable precise drug layering, predictable dissolution, and uniform content distribution in capsules or tablets. A narrow and well-characterized PSD improves processability and coating uniformity. It also supports reproducible drug delivery performance in multiparticulate systems. Inert spheres such as CELLETS® offer tight PSD and high sphericity. Therefore, they provide robust cores for dosage forms ranging from low-dose products to extended-release multiparticulates.
A Publication Worth Reading: computerized image analysis
The publication by Heinicke and Schwartz [1] evaluates computerized image analysis for measuring PSD in pharmaceutical spheres and pellets. The study covers particle size ranges from approximately 425 to 1400 micrometers. Traditional sizing methods, such as sieve analysis, provide limited resolution and statistical detail. In contrast, image analysis demonstrated high repeatability and sensitivity. It quantified size differences that traditional methods could not detect. The authors compared two inert sphere lots before drug layering in a fluid-bed rotor granulator. Differences in starting PSD appeared clearly in the resulting granulated products. This result highlights the importance of core PSD for downstream performance. Furthermore, image analysis detected coating thickness increments as small as four micrometers.
The authors also investigated sampling strategies and sample sizes necessary for reliable measurements, recognizing that an appropriate representativeness of sample draws is critical for statistically meaningful PSD outcomes. Importantly, image analysis captured not only size distribution but also provided visual and morphological data for each particle, thereby enriching the dataset beyond mere dimensional statistics. The technique’s effectiveness was tested in both laboratory and commercial scale contexts, including measuring polymer-coated nonpareils during continuous fluid-bed processing. The similarity between in-situ samples (collected via process sampling ports) and whole batch samples suggested that fluid-bed processes in these systems provide sufficiently homogeneous conditions for representative PSD capture by image analysis.
Beyond the direct findings, the work situates PSD measurement via image analysis within a broader pharmaceutical quality landscape. Historically, PSD has been a critical parameter because it influences particle flow, coating behavior, drug layering uniformity, content uniformity, and ultimately drug release characteristics. The continuous development of in-line and at-line image analysis methods positions this approach as part of process analytical technology (PAT), enabling more dynamic control and monitoring of multiparticulate manufacturing.
Advances in Image Analysis for Determining Particle Size Distributions of Inert Spheres
Image analysis has evolved rapidly as a high-resolution method for determining PSD in pharmaceutical spheres. It directly measures individual particle dimensions and morphologies with high precision. Unlike sieve analysis or laser diffraction, image analysis provides particle-by-particle size and shape data. Therefore, it improves PSD accuracy, reproducibility, and visualization during development and quality control. Dynamic image analysis platforms process thousands of particles within minutes. As a result, they generate robust PSD and shape statistics correlated with functional performance criteria.
Important facts include the distinction between number-based and volume-based PSD measures. Metrics such as D10, D50, and D90 describe the spread and balance of the size distribution. In addition, image analysis extracts shape parameters such as sphericity and aspect ratio. These parameters strongly influence flow properties and coating behavior. Moreover, image analysis enables rapid in-process feedback for monitoring and control. This capability supports coating thickness control and ensures batch-to-batch consistency.
Persisting Obstacles
Despite these advances, obstacles persist. Adequate sample preparation is essential to avoid overlapping particles and bias, especially when using static imaging methods. Agglomeration, depth-of-field effects, and segmentation challenges in image processing can introduce measurement uncertainty if not properly managed. Opportunities exist to integrate enhanced machine vision, artificial intelligence (AI), and real-time imaging to improve discrimination of individual particles in complex mixtures or in high-throughput manufacturing environments. In-line imaging systems with real-time analytics can transform PSD from a static quality attribute to a dynamic process performance indicator.
CELLETS® exemplify the concept of narrow PSD and high surface homogeneity in inert spheres. These microcrystalline cellulose pellets exhibit tight particle size distributions within specified fractions (e.g., 100–200 µm, 150–300 µm, up to 1000-1400 µm) with high sphericity, low friability, and consistent surface characteristics that enhance coating uniformity and enable predictable performance in multiparticulate dosage forms. The narrow PSD and uniform surface enable reproducible drug layering, optimized flow properties, and controlled release profiles, making them ideal cores in fluid bed and Wurster coating operations.
Conclusion and Outlook
The study by Heinicke and Schwartz underscores the value of image analysis for PSD determination. They compared traditional sizing methods with image analysis for inert spheres and coated pharmaceutical pellets. The detection of fine particle diameter differences and detailed morphology supports formulation design, process control, and quality assurance. Future image analysis developments, including AI and in-line PAT integration, will further enhance PSD measurement capabilities. These advances will enable real-time adjustments and closed-loop control in pellet manufacturing. As multiparticulate drug delivery advances, precise characterization of Particle Size Distributions of Inert Spheres remains essential. This precision supports consistent therapeutic outcomes, regulatory compliance, and manufacturing efficiency. Ongoing innovations in imaging hardware, software, and data analytics will strengthen real-time quality control and predictive modeling.
References
[1] G. Heinicke, J. B. Schwartz, Pharmaceutical Development and Technology 2005 (9) 4, 359-367, doi:10.1081/PDT-200032996
CELLETS® Pharmaceutical Starter Cores for Pellets & Functional Coatings
CELLETS® are high-purity pharmaceutical starter cores. They combine spherical geometry with narrow particle size distribution and defined density. They provide reproducible carriers for functional coatings and enable controlled layer formation in fluid bed and drum coating processes. Thanks to their uniform geometry, CELLETS® ensure stable fluidization, consistent rolling, and homogeneous wetting during coating. This guarantees uniform layer thicknesses and precise control of active ingredient release.
In controlled-release applications—such as sustained-release, delayed-release, or gastro-resistant systems—CELLETS® support reproducible release profiles. They minimize variability in active ingredient application and polymer layer thickness, creating robust, scalable formulations. CELLETS® enable efficient transfer from formulation development to production scale, improving process reliability and batch-to-batch consistency.
Standardized Starter Cores for GMP-Compliant Processes
CELLETS® are manufactured under controlled conditions with reproducible physical properties. Their narrow particle size, defined density, and high sphericity support consistent process control. This facilitates equipment and process qualification. Regulatory documentation (e.g., DMF information) and GMP compatibility allow CELLETS® to be used across the entire product lifecycle. Using standardized starter cores reduces regulatory risks and supports process validation and batch consistency.
Seamless Transfer from Development to Production
CELLETS® enable a smooth scale-up from lab to pilot and commercial production without altering material properties. This simplifies understanding and control of critical process parameters (CPPs). Formulations developed on CELLETS® can scale reproducibly, shortening development timelines and minimizing process adjustments.
Controlled Release & Enteric Coating Precision
CELLETS® provide a neutral, robust core for controlled or delayed drug release. Their uniform surface allows homogeneous application of functional polymer layers, such as sustained-release or enteric coatings. They reduce variability in layer thickness and drug distribution, ensuring reproducible release profiles. CELLETS® support the development of stable controlled-release and enteric coating systems in both R&D and commercial production.
