Evolution of structure and properties of granules containing microcrystalline cellulose and polyvinylpyrrolidone during high-shear wet granulation

Evaluation of binders in twin-screw wet granulation - Optimization of tabletability

The influence of hydroxypropyl cellulose type (HPC-SSL SFP, HPC-SSL), concentration (2 %, 3.5 %, 5 %) and filler (lactose, calcium hydrogen phosphate (DCP)/microcrystalline cellulose (MCC)) on twin-screw wet granulation and subsequent tableting was studied. The aim was to identify the formulation of the highest tabletability which still fulfills the requirements of the disintegration. Lactose combined with 5 % binder enabled a higher tabletability and a faster disintegration than DCP/MCC. It was found that tabletability of lactose formulations can be increased by higher binder concentration and higher compression pressure while tabletability of DCP/MCC formulations can be only increased by higher compression pressure. It was observed that batches containing DCP/MCC failed the disintegration test, if the highest binder concentration and the highest compression pressure were used. To ensure a fast disintegration, the compression pressure or at least the binder concentration had to be low. Changing the disintegrant and its localization improved the DCP/MCC formulation, resulting in faster disintegration than lactose tablets. However, it also resulted in a lower tabletability. In this study best tablets were achieved with 3.5 % or 5 % binder and lactose as filler. These tablets presented the highest tabletability but still disintegrated in less than 500 s.

Cylindrical granules in the development of mesalazine solid formulations (Ⅱ): The contribution of high aspect ratio to favorable tabletability

Recently, cylindrical granules have been applied in pharmaceutical fields and their aspect ratio (AR) is considered an important factor in the manufacturing process. However, the relationships between AR and the tableting process were seldom reported. This study aims to clarify the role of AR in the tableting process of cylindrical granules. First, mesalazine cylindrical granules with different AR were extruded, and their physical attributes were then comprehensively characterized. Subsequently, their compression behaviors and tableting performances were systematically assessed. Notably, it was found that the cylindrical granules with high AR possessed good anti-deformation capacity and favorable tabletability. Finally, the dissolution test suggested that tablets compressed from cylindrical granules with higher AR showed lower dissolution rates. Collectively, findings in this study identified that the AR of cylindrical granules was a critical factor in the tableting process and provided valuable guidance for the application of these granules in oral solid formulations.

Cylindrical granules in the development of mesalazine solid formulations (Ⅰ): Physical properties, compression behaviors, and tableting performances

Cylindrical granules have been employed in the pharmaceutical industry. However, to our knowledge, the study on the compressibility and tabletability of cylindrical granules has not been reported. This study aimed to explore the effects of the physical properties of cylindrical granules on the compression behaviors and the tableting performances, with mesalazine (MSZ) as a model drug. First, the six formulations of MSZ cylindrical granules were extruded by changing the ethanol proportion in the binder. Then, the physical characteristics of MSZ cylindrical granules were systematically studied. Subsequently, the compressibility and tabletability were evaluated using different mathematic models. It was worth noting that highly porous cylindrical granules possessed favorable compressibility and good tabletability due to the increased pore volume, reduced density, and decreased fracture forces. Finally, dissolution tests were conducted and highly porous granules showed higher dissolution rates than the less porous ones, but an opposite trend was observed for the corresponding tablets. This study proved the importance of physical properties in the tableting process of cylindrical granules and provided strategies to improve their compressibility and tabletability.

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

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

The effect of granules characters on mechanical properties of press-coated tablets: A comparative study

The aim of this study was to investigate the correlation between critical granules characters (including particle size, surface roughness, and apparent porosity) and mechanical properties of press-coated tablets. Granules of a model formulation were prepared through Roll Compaction Granulation (RCG), High Shear Granulation (HSG), and Fluidized Bed Granulation (FBG) to prepare granules with different surface roughness and apparent porosity. The surface roughness and porosity of granules had a significantly greater effect on mechanical properties than the particle size of granules. Whether for brittle or plastic materials, FBG granules with the roughest surface and the greatest apparent porosity exhibited the best compression properties. The elastic recovery test, the interlayer adhesion forces study, the break pattern test, and the X-ray microcomputed tomography investigation suggested that granules with great apparent porosity and rough surfaces could contribute to the production of stable press-coated structures. Moreover, for press-coated tablets prepared using granules, the proper granules in the coat layer could eliminate the side effect of the rigid core on the mechanical strength. The above understandings will be conducive to the selection of compatible and appropriate granules characters, which can enhance mechanical properties and extend the application of press-coated tablets.

Systematic Study of the Effects of High Shear Granulation Parameters on Process Yield, Granule Size, and Shape by Dynamic Image Analysis

The aim of the work was to analyze the influence of process parameters of high shear granulation on the process yield and on the morphology of granules on the basis of dynamic image analysis. The amount of added granulation liquid had a significant effect on all monitored granulometric parameters and caused significant changes in the yield of the process. In regard of the shape, the most spherical granules with the smoothest surface were formed at a liquid to solid ratio of ≈1. The smallest granules were formed at an impeller speed of 700 rpm, but the granules formed at 500 rpm showed both the most desirable shape and the highest process yield. Variation in the shape factors relied not only on the process parameters, but also on the area equivalent diameter of the individual granules in the batch. A linear relationship was found between the amount of granulation liquid and the compressibility of the granules. Using response surface methodology, models for predicting the size of granules and process yield related to the amount of added liquid and the impeller speed were generated, on the basis of which the size of granules and yield can be determined with great accuracy.

Performance Evaluation of a Novel Biosourced Co-Processed Excipient in Direct Compression and Drug Release

This study exposes the potential usefulness of a new co-processed excipient, composed of alginic acid and microcrystalline cellulose (Cop AA-MCC), for the preparation of immediate drug release tablets by direct compression. Evaluation of the physical and mechanical properties as well as the disintegration behavior of Cop AA-MCC in comparison to commercial co-processed excipients (Cellactose^®, Ludipress^®, Prosolv^® SMCC HD90 and Prosolv^® ODT) and to the physical mixture of the native excipients (MCC and AA), was carried out. The obtained results illustrate the good performance of Cop AA-MCC in terms of powder flowability, tablet tensile strength, compressibility, and disintegration time. Although, this new co-processed excipient showed a slightly high lubricant sensitivity, which was explained by its more plastic than fragmentary deformation behavior, it presented a low lubricant requirement due to the remarkably low ejection force observed during compression. Compression speed and dwell time seemed not to affect significantly the tabletability of Cop AA-MCC. The study exposed evenly the performance of Cop AA-MCC compared to Prosolv^® ODT, in terms of tabletability and dissolution rate of Melatonin. Cop AA-MCC presented comparable hardness, lower dilution potential, higher lubricant sensitivity, lower ejection force, and faster Melatonin's release time than Prosolv^® ODT. In summary, Cop AA-MCC exhibited interesting physical, mechanical, and biopharmaceutical properties, which demonstrate its concurrence to commercially available co-processed excipients. Furthermore, the simplicity of its composition and the scalability of its elaboration makes this multifunctional excipient highly recommended for direct compression.

Functionality evaluation of co-processed excipients as diluents in tablets manufactured by wet granulation

Diluents are essential components of a tablet formulation. The type of diluent used in a formulation influences the quality of tablets produced from that formulation. The aim of this study was to evaluate the tableting properties of co-processed excipients (C-PEs) incorporated as diluents in tablet formulation by wet granulation. Metronidazole tablets were prepared by wet granulation incorporating different diluents that were either single component excipients (SCEs) (lactose and microcrystalline cellulose) or C-PEs (Ludipress®, StarLac®, Prosolv® and AVICEL®HFE). The granules obtained for each formulation were evaluated for particle size analysis, flow properties and compression properties. Tablets weighing 500 mg were compressed from the metronidazole granules on a Single Station Tablet Press using a 12 mm punch and die tooling system. The tablets were kept for 24 h post-production, and the properties of weight uniformity, thickness, tensile strength, friability, disintegration time and dissolution profile evaluated subsequently. Results of granule properties showed that variations in parameters evaluated was as a result of differences in the type and composition of diluent used in formulation. Compactibility and tabletability profile of metronidazole granules revealed a better performance with granules processed with C-PE based diluents compared to SCE-based diluents. Tablets formulated with C-PEs as diluents were uniform in tablet weight, disintegrated faster and yielded a faster drug release compared to tablet formulations containing SCEs as diluent. This study reveals the performance advantage of C-PEs as diluents in tablets manufactured by wet granulation and highlights the importance of rational selection of excipients during tablet formulation.

Effect of Hydroxypropyl Cellulose Level on Twin-Screw Melt Granulation of Acetaminophen

This study investigated the effect of binder level on the physicochemical changes and tabletability of acetaminophen (APAP)-hydroxypropyl cellulose (HPC) granulated using twin-screw melt granulation. Even at 5% HPC level, the tablet tensile strength achieved up to 3.5 MPa. A minimum of 10% HPC was required for the process robustness. However, 20% HPC led to tabletability loss, attributable to the high mechanical strength of APAP granules. The over-granulated APAP granules had thick connected HPC scaffold and low porosity. Consequently, these granules were so strong that they underwent a lower degree of fracture under compression and higher elastic recovery during decompression. HPC was enriched on the surface of APAP extrudates at all HPC levels. Amorphous APAP was also observed on the extrudate surface at 20% HPC level, and it recrystallized within 24 h storage. To achieve a robust process and optimal improvement in APAP tabletability, the preferred HPC level was 10 to 15%.

A microcrystalline cellulose based drug-composite formulation strategy for developing low dose drug tablets

The uniformity of active pharmaceutical ingredient (API) is a main challenge associated with manufacturing low dose tablets. Here, we present a binder enhanced API-microcrystalline cellulose (BEAM) approach to address this challenge. In the BEAM approach a powder is prepared by spraying a PVP hydro-alcoholic solution, which contains API at an appropriate concentration, onto a powder bed of microcrystalline cellulose (MCC) under high shear. BEAM powders of 5 model APIs, with solubility spanning a range of 5 orders of magnitude, all exhibited excellent flowability, tabletability, and low ejection force. Therefore, all BEAM powders could be directly compressed into tablets with excellent API uniformity and fast disintegration without using any other excipients. Compared to traditional ways to address content uniformity problems, this formulation strategy is much more robust and simpler, making it a potential platform technology for manufacturing tablets of potent APIs.

New gentle-wing high-shear granulator: impact of processing variables on granules and tablets characteristics of high-drug loading formulation using design of experiment approach

The aim of this work was to study the application of design of experiment (DoE) approach in defining design space for granulation and tableting processes using a novel gentle-wing high-shear granulator. According to quality-by-design (QbD) prospective, critical attributes of granules, and tablets should be ensured by manufacturing process design. A face-centered central composite design has been employed in order to investigate the effect of water amount (X₁), impeller speed (X₂), wet massing time (X₃), and water addition rate (X₄) as independent process variables on granules and tablets characteristics. Acetaminophen was used as a model drug and granulation experiments were carried out using dry addition of povidone k30. The dried granules have been analyzed for their size distribution, density, and flow pattern. Additionally, the produced tablets have been investigated for; weight uniformity, breaking force, friability and percent capping, disintegration time, and drug dissolution. Results of regression analysis showed that water amount, impeller speed and wet massing time have significant (p < .05) effect on granules and tablets characteristics. However, the water amount had the most pronounced effect as indicated by its higher parameter estimate. On the other hand, water addition rate showed a minimal impact on granules and tablets properties. In conclusion, water amount, impeller speed, and wet massing time could be considered as critical process variables. Thus, understanding the relationship between these variables and quality attributes of granules and corresponding tablets provides the basis for adjusting granulation variables in order to optimize product performance.

Development and Optimization of a Wet Granulation Process at Elevated Temperature for a Poorly Compactible Drug Using Twin Screw Extruder for Continuous Manufacturing

The objective of this study was to enhance tabletability of a poorly compactible drug, acetaminophen, by wet granulation using twin screw extruder at high temperature. It was desired that there would be minimum amounts of excipients used and the granules obtained after extrusion would be dry and fall within a size range suitable for tableting without any further processing. Mixtures of acetaminophen (95%) with binders (5% povidone or partially pregelatinized starch) were wet granulated through twin screw extruder at 70°C by adding 7% w/w water. The process had a short granulation time (<1 min), and, on account of the elevated processing temperature used, no drying after extrusion was needed. By optimizing formulation and processing parameters, >90% granules in the size range of 125 to 1000 μm (<3% above 1000 μm and <7% below 125 μm) were obtained without any milling. When the granules were compressed by adding 1% disintegrant and 0.5% lubricant extragranularly, tablets produced (93.6% drug load) had good mechanical strength having hardness >1.7 MPa, which was superior to that of tablets prepared by conventional high shear wet granulation. As the granules could be extruded continuously and did not require drying and milling, the method was amenable to continuous processing.