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
https://cellets.com/wp-content/uploads/2026/06/Multilayered-pharmaceutically-active-compound-small.jpg533852Bastian Arlthttps://cellets.com/wp-content/uploads/2016/10/Logo_Cellets_2016_website.pngBastian Arlt2026-07-21 16:17:382026-07-21 16:17:38Multilayered pharmaceutically active compound-releasing microparticles in a liquid dosage form
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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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 Different Pelletization Techniques and Their Functionality in Drug Formulations
Different pelletization techniques form a core part of pharmaceutical manufacturing for solid dosage forms that deliver active pharmaceutical ingredients (APIs) with enhanced performance. Pelletization, a process that generates small, uniform spherical particles, improves flow properties, enables controlled or delayed release, and reduces local irritation in the gastrointestinal tract compared with conventional tablets and capsules. These techniques include direct pelletization, layering pelletization, extrusion-spheronization, spray drying, and other advanced methods, each offering specific functional benefits. Direct pelletization allows quick single-step formation with minimal equipment and lower cost. Layering pelletization deposits drug onto inert cores to improve drug loading and modify release profiles. More complex methods like extrusion-spheronization yield highly uniform pellets but require more processing time. Across all approaches, the choice of technique affects drug dissolution, stability, and manufacturability, and each technique opens opportunities to tailor drug release, enhance bioavailability, and optimize patient compliance through multiparticulate delivery systems.
Summary of the Thesis
The PhD thesis [1] “Application of High-Shear Granulator in Different Pelletization Techniques” by Azza Asim Khalid Mahmoud explores high-shear granulator applications. Furthermore, it demonstrates how these granulators improve different pelletization techniques to produce optimized drug delivery pellets. Consequently, different pelletization techniques become essential for solid dosage forms, enhancing flow properties and ensuring uniform size distribution. Moreover, the study highlights how these techniques enable precise control over drug release while equipment choice reduces cost and streamlines production. In addition, both direct pelletization and layering pelletization are analyzed within a high-shear granulator framework. Therefore, Quality by Design (QbD) principles guide the definition of process parameters that impact pellet quality. Through risk assessments, design of experiments (DoE), and optimization strategies, critical parameters are identified. These include impeller speed, chopper speed, binder volume, and granulating liquid, which strongly affect pellet size, yield, hardness, and dissolution. Overall, the research confirms that mastering different pelletization techniques enhances pharmaceutical pellet formulation efficiency and performance.
Direct pelletization with high-shear granulation
The thesis demonstrates that direct pelletization with high-shear granulation can produce pellets with desirable physical attributes and consistent drug distribution through careful experimental design. By applying a full factorial design and central composite design, the author constructs an optimal design space. The study also incorporates active pharmaceutical ingredients—amlodipine besylate and hydrochlorothiazide—showing how optimized pellets retain good content uniformity and dissolution performance when loaded. On the layering pelletization front, MCC cores serve as a base for drug deposition, with micro-computed tomography and thermal analysis confirming structural features that contribute to improved drug release. The research highlights how the high-shear granulator facilitates physical transformations such as partial amorphization of loaded drugs, which can enhance dissolution rates.
The thesis underscores the advantages of integrating QbD concepts into pelletization, improving reproducibility and understanding of how process variables interact. Overall, the study provides a comprehensive view of how different pelletization techniques benefit from high-shear granulation to produce robust pellet formulations with desirable critical quality attributes.
Use of CELLETS® in the Study
Within the thesis, CELLETS®—spherical microcrystalline cellulose cores—play a key role in the layering pelletization process. These inert cores are typically defined in uniform sizes of approximately 100 µm to 1400 µm. They provide a stable and consistent substrate onto which drug combinations (hydrochlorothiazide and amlodipine besylate) are deposited under high-shear conditions. The application of CELLETS® enhances layering efficiency, facilitates uniform drug distribution, and contributes to improved pellet morphology and mechanical integrity. Their use is integral to investigating how high-shear granulation affects drug layering and the resulting pharmacotechnical properties of the pellets.
Conclusion and Outlook
This thesis confirms that different pelletization techniques, particularly direct and layering methods, gain substantial functional advantages when implemented with high-shear granulation and QbD strategies. The research shows that such integration leads to pellets with optimized size, mechanical strength, and drug release characteristics. Moreover, the use of CELLETS® strengthens drug layering approaches and helps maintain uniformity in multiparticulate systems. Future research may expand on scaling these methods for commercial production, exploring additional API combinations. They are employing real-time monitoring technologies to further enhance control over pellet quality. By advancing the understanding of how process parameters affect critical quality attributes, this work positions high-shear granulation. This technology is a versatile tool for modern drug formulation technologies.
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Enzyme‑cleavable methadone prodrugs: Functionality, Opportunities, and Summary of US20250361205A1
Introduction to Enzyme‑cleavable methadone prodrugs
Enzyme‑cleavable methadone prodrugs represent a novel class of pharmacological agents designed to provide controlled release of methadone only after specific enzymatic activation. These prodrugs attach an enzyme‑cleavable promoiety to the methadone molecule, rendering it inactive until a target enzyme cleaves the linkage in vivo. This mechanism reduces misuse potential and provides more predictable pharmacokinetics compared to conventional methadone formulations. By depending upon specific enzymatic activity, this prodrug design can improve safety and minimize risks associated with inappropriate administration or overdose, while maintaining therapeutic efficacy for opioid dependence or chronic pain management.
Beyond safety, enzyme‑cleavable methadone prodrugs offer opportunities in advanced drug formulation. They enable precise control over the timing and extent of methadone release based on the activity of endogenous enzymes. As a result, formulators can tailor release rates and reduce systemic peaks that commonly contribute to adverse effects or abuse. These prodrugs also permit formulation with excipients or technologies that further modulate release profiles, including multiparticulate systems or coatings. In addition, controlled enzyme activation provides a strategy to optimize oral delivery, enhance patient compliance, and potentially reduce the burden of supervised dosing programs in opioid maintenance therapy.
Summary of this patent
The patent application US20250361205A1 discloses enzyme‑cleavable methadone prodrugs and corresponding methods of use, focusing on prodrugs that deliver methadone through enzymatically‑controlled release. These prodrugs contain a promoiety linked to methadone that requires cleavage by specific enzymes, such as digestive proteases, before the active opioid is liberated. By requiring enzymatic cleavage followed by intramolecular cyclization to release active methadone, the design significantly lowers the susceptibility to accidental or intentional misuse, including inappropriate routes of administration or chemical tampering.
The disclosed prodrug moieties can include amino acid residues or peptides of up to about 100 amino acids linked via an amide bond to the methadone nitrogen. By selecting promoieties that are substrates for particular enzymes, formulators can adjust release kinetics based on the target enzyme’s activity and distribution. For example, gastrointestinal enzymes like trypsin are contemplated as triggers for prodrug activation. The application also describes including enzyme inhibitors in the pharmaceutical composition to attenuate the rate of enzymatic cleavage when desired. This addition can further control release profiles and reduce unintended rapid activation.
The patent describes general chemical structures of enzyme‑cleavable methadone prodrugs, outlining variations in functional groups and linkers that influence both stability and enzymatic susceptibility. These structures include several formulae (e.g., MD‑(I), MD‑(II), MD‑(III)), each representing different classes of promoieties attached to the methadone core. Notably, upon enzymatic cleavage of the promoiety, a stable cyclic urea or other cyclic group forms, which is pharmaceutically acceptable and of low toxicity. The description also covers pharmaceutically acceptable salts, solvates, and crystalline forms of the prodrugs, enhancing formulation versatility.
A key advantage emphasized in this disclosure is the reduction of excessive plasma methadone levels when the prodrug is administered improperly. Because the prodrug cannot be converted to methadone without specific enzymatic action and cyclization, the risk of overdose is reduced. Furthermore, the document details that trypsin inhibitors or other enzyme modulators may be co‑formulated to regulate the enzymatic activation rate. In addition to the chemical and pharmacokinetic considerations, the application mentions pharmaceutical compositions that include typical excipients, such as fillers, binders, and disintegrants, that support conventional formulation processes for oral delivery.
Use of CELLETS® in This Context
Although CELLETS® (highly spherical microcrystalline cellulose pellets used as starter cores in multiparticulate drug delivery systems) are not explicitly referenced in US20250361205A1, the broader formulation context suggests potential relevance. CELLETS® provide uniform and inert starter cores that support controlled layering of active pharmaceutical ingredients. In multiparticulate systems, CELLETS® improve coating uniformity, flow properties, and controlled release profiles in oral dosage forms. These characteristics make them useful for advanced prodrug formulations where release kinetics and consistency are critical, particularly when precise layering of enzyme‑cleavable prodrug moieties is required. Unlike conventional inert cores, CELLETS® enable predictable performance and facilitate scalable manufacturing for complex oral formulations.
In this patent, some particle sizes of CELLETS® are explicitely named:
In summary, enzyme‑cleavable methadone prodrugs offer a promising advancement in opioid therapy and formulation science, combining controlled enzymatic activation with enhanced safety. The patent US20250361205A1 details chemical constructs and methods that reduce misuse potential and allow sophisticated control of drug release. Given ongoing needs for safer opioid medications, these prodrugs could transform maintenance therapy and pain management by minimizing overdose risks and improving patient compliance. Looking forward, integrating technologies such as multiparticulate delivery systems and optimized excipients (e.g., CELLETS®) will further refine dosing precision and therapeutic outcomes. Future research and clinical evaluation will determine how these designs perform in real‑world settings, including their impact on pharmacokinetics, abuse deterrence, and commercial viability.
Patent Summary
Name of Patent: Enzyme-cleavable methadone prodrugs and methods of use thereof
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Hot-melt coating materials improve efficiency and product quality in pharmaceutical and industrial manufacturing. They melt when heated and solidify quickly, forming strong, uniform coatings on various surfaces. As a result, manufacturers reduce production time, lower costs, and avoid using solvents. Furthermore, understanding wetting behavior and delamination is critical to optimize coating performance. For example, CELLETS® 1000 microcrystalline cellulose pellets serve as excellent starter cores, promoting uniform wetting and consistent coating thickness. Consequently, hot-melt coating materials have become a reliable solution for modern manufacturing needs.
Enhancing pharmaceutical and industrial applications by hot-melt coating materials
In the study titled Delamination and Wetting Behavior of Natural Hot-Melt Coating Materials, published in Powder Technology [1], the authors investigated the delamination and wetting behaviors of various natural materials.The research aimed to understand how these materials interact with substrates during the coating process, which is crucial for applications in the pharmaceutical industry.The study utilized laboratory coating experiments and micro-computed tomographic measurements to assess delamination frequency, and a drop shape analyzer to evaluate wetting behavior.Interestingly, the study found no correlation between delamination and wetting behavior, suggesting that other factors may influence delamination in hot-melt coatings.
Among the materials tested, CELLETS® 1000, a type of microcrystalline cellulose (MCC) pellet with a size range between 1000 and 1400 µm, was highlighted for its suitability in hot-melt coating applications.These spherical pellets are known for their chemical inertness, low friability, high sphericity, and smooth surface, making them ideal as starter cores for multiparticulate drug delivery systems.In the context of the study, CELLETS® 1000 demonstrated excellent wetting properties with contact angles ranging from 10° to 18°, which is favorable for uniform coating.However, the study did not find a direct correlation between wetting behavior and delamination, indicating that other factors may play a more significant role in delamination during hot-melt coating processes. Researchers assume that delamination may have resulted from the different thermal expansion coefficients of the carrier particle and the coating material [2]. A change in temperature may have led to thermal stresses and may have promoted spalling or delamination. Subsequent swelling of a hygroscopic carrier material due to moisture could also lead to structural
changes in the coating structure and might cause delamination.
Use of CELLETS® in hot-melt coating processes
The use of CELLETS® in hot-melt coating processes offers several advantages.Their uniform size distribution and smooth surface contribute to consistent coating thickness and quality.Additionally, the chemical inertness of CELLETS® ensures compatibility with a wide range of coating materials, reducing the risk of undesirable interactions.These characteristics make CELLETS® a reliable choice for developing controlled-release formulations and enteric coatings in pharmaceutical applications.
In summary, the study underscores the importance of understanding the delamination and wetting behaviors of natural hot-melt coating materials.While CELLETS® 1000 exhibited favorable wetting properties, the lack of correlation between wetting behavior and delamination suggests that other factors should be considered when selecting materials for hot-melt coating processes.Further research is needed to identify these factors and optimize coating processes for improved product performance.
[2] S. Ebnesajjad, A.H. Landrock, Introduction and adhesion theories, Adhesives Technology, Handbook, 38, Elsevier 2015, pp. 1–18; doi: 10.1016/B978-0-323-35595-7.00001-2.
Understanding Hot-Melt Coating Materials
Hot-melt coating materials are thermoplastic substances that bond effectively to substrates when melted. Their melting point, adhesion properties, and chemical compatibility directly influence coating uniformity and durability. Therefore, selecting the correct material is crucial for minimizing delamination and ensuring product quality. Additionally, their solvent-free nature makes them environmentally friendly and cost-efficient.
Optimizing Coating with CELLETS®
CELLETS® offer significant advantages as starter cores in hot-melt coating processes. Their spherical shape and smooth surface promote uniform wetting and consistent coating thickness. Furthermore, their chemical inertness ensures compatibility with diverse coating materials, reducing the risk of unwanted interactions. Consequently, these MCC spheres support reliable and high-quality coating outcomes in both pharmaceutical and industrial applications.
The present invention generally relates to enteric-coated particles containing lactoferrin. More specifically, the present invention provides an enteric-coated particle comprising (or consisting essentially of): a) a core comprising (or consisting essentially of) an inert core-forming material selected from cellulose polymer, sugar, sugar alcohol, starch and carnauba wax; b) a first coating layer substantially covering the core and comprising (or consisting essentially of) b-1) lactoferrin, b-2) a pharmaceutically acceptable binder and optionally b-3) one or more other suitable excipients, such as a plasticizer; and c) a second coating layer substantially covering the first coating layer and comprising (or consisting essentially of) c-1) an enteric coating material, and optionally c-2) one or more suitable excipients, such as a plasticizer and/or an anti-tacking agent. The present invention further provides pharmaceutical compositions and oral dosage forms comprising one or more particles according to the present invention. [1]
Enteric-coated particles with CELLETS® and other starter beads
This formulations is based on starter beads, exemplary such as sugar, wax or microcrystalline cellulose (MCC). For the latter material MCC, specifically such as CELLETS® 100, CELLETS® 200, CELLETS® 350, CELLETS® 500, CELLETS® 700, or CELLETS® 1000 are mentioned. Through coating and layering of CELLETS® with excipients and the active, a modified release is obtained wherein at most 10% of lactoferrin is released from the particle within 120 minutes.
Document information
Document Type and Number: (“enteric-coated particles containing lactoferrin”)
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This article “Amorphous Solid Dispersions Layered onto Pellets – An Alternative to Spray Drying?” is an excerpt from the publication of Neuwirth et al., Pharmaceutics 2023, 15(3), 764; https://doi.org/10.3390/pharmaceutics15030764.
Abstract
Spray drying is one of the most frequently used solvent-based processes for manufacturing amorphous solid dispersions (ASDs). However, the resulting fine powders usually require further downstream processing when intended for solid oral dosage forms. In this study, we compare properties and performance of spray-dried ASDs with ASDs coated onto neutral starter pellets in mini-scale. We successfully prepared binary ASDs with a drug load of 20% Ketoconazole (KCZ) or Loratadine (LRD) as weakly basic model drugs and hydroxypropyl-methyl-cellulose acetate succinate or methacrylic acid ethacrylate copolymer as pH-dependent soluble polymers. All KCZ/ and LRD/polymer mixtures formed single-phased ASDs, as indicated by differential scanning calorimetry, X-ray powder diffraction and infrared spectroscopy. All ASDs showed physical stability for 6 months at 25 °C/65% rH and 40 °C/0% rH. Normalized to their initial surface area available to the dissolution medium, all ASDs showed a linear relationship of surface area and solubility enhancement, both in terms of supersaturation of solubility and initial dissolution rate, regardless of the manufacturing process. With similar performance and stability, processing of ASD pellets showed the advantages of a superior yield (>98%), ready to use for subsequent processing into multiple unit pellet systems. Therefore, ASD-layered pellets are an attractive alternative in ASD-formulation, especially in early formulation development at limited availability of drug substance.
Materials
The model drugs ketoconazole (KCZ) and loratadine (LRD) were purchased from Sris Pharmaceuticals (Hyderabad, India). HPMCAS LG (hydroxypropyl-methylcellulose acetate succinate, wt%: methoxyl 20–24%, hydroxypropyl 5–9%, succinyl 14–18%; Mw = 18,000, HPMC-AS) was donated from Shin-Etsu Chemical (Tokyo, Japan). Eudragit L100-55 (methacrylic acid ethylacrylate copolymer, ratio 1:1, Mw = 320,000, EL100-55) was donated by Evonik (Darmstadt, Germany). Cellets 1000 (microcrystalline cellulose starter pellets, 1000–1400 µm) were provided by Glatt Pharmaceutical Services (Binzen, Germany). A detailed list of the pellets’ characteristics is shown in Table 1. Ethanol 96% (v/v) (technical grade) used in the sample preparation, and methanol (analytical grade) used for the HPLC analytics as well as the buffer salts disodium mono-hydrogen phosphate dodecahydrate (Na2HPO4·12H2O) and monosodium dihydrogen phosphate dodecahydrate (NaH2PO4·12H2O) were obtained from VWR Chemicals GmbH (Darmstadt, Germany).
Pellet Properties
d50 (xc min) [µm]
1123.44
(±7.36)
SPAN
0.166
(±0.002)
b/l
0.893
(±0.000)
SPHT
0.956
(±0.001)
Particle density [g/cm3]
1.452
(±0.016)
Sm [cm2/g]
36.41
(±0.29)
Table 1. Pellet properties of Cellets 1000. d50: mean particle diameter determined by the particle width; SPAN: width of the particle distribution; b/l: aspect ratio; SPHT: sphericity; Sm: specific surface area.
Pellet Coating (PC)
For pellet coating (PC) a laboratory scale fluid bed system Mini Glatt equipped with a Micro-Kit (Glatt GmbH, Binzen, Germany) was used. The coating was applied with a 0.5 mm two-fluid nozzle in bottom spray using the special bottom plate of the Micro-Kit to emulate a three-fluid nozzle with micro-climate. In the beginning, the machine was filled with 25.0 g of Cellets® 1000. The following process parameters were maintained throughout the process: Process gas flow 30 m3/h, product temperature 30.0 ± 1.0 °C (resulting inlet temperature 32–35 °C), spray pressure 1.5 bar and spray rate 1.0 ± 0.2 g/min. The final pellets had a theoretical drug-load of 10% (w/w) due to the fact that ASD and core pellets were used in a 1:1-ratio. […] To prepare the spraying solutions, the API and polymer were dissolved in ethanol 96% (v/v) under continuous stirring (solid content of 10% (w/w)). Prior to spraying, each solution was sonicated for 15 min to ensure complete dissolution of the components.
Subsequently, the coated pellets were manually sieved with a 2 mm mesh to eliminate multicore pellets. The pellets were dried under vacuum for 24 h at the same conditions as the SD powder.
Conclusions
In this study, we successfully prepared binary single phase ASDs of KCZ and LRD as weakly basic, slow crystallizing model APIs (drug load 20% (w/w)) using HPMC-AS or EL100-55 as pH-dependent soluble polymers via fluid bed pellet coating and spray drying. While the received ASD-pellets would not require further downstream processing other than capsule filling or tableting, the fine SD powder had to be transformed into dry granules. In combination with the slow crystallizers, KTZ and LOR, both manufacturing processes resulted in single-phased ASDs of high physical stability (up to 6 months) and similar dissolution performance when normalized to the total outer surface. The dissolution rate depends mainly on this total outer particle surface of the respective sample, independent of the manufacturing process, while the porosity of the sample had a minor impact on its dissolution behavior.
Especially for early formulation development, the high yield and ease of handling due to the pellet properties are strong advantages over the standard spray drying process. Nevertheless, the long process time in larger scale requires further process optimization in fluidized bed processing.
Adobe Firefly
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