Understanding the roles of compaction pressure and crystal hardness on powder tabletability through bonding area - Bonding strength interplay

Bonding area (BA) and bonding strength (BS) interplay dictates tensile strength of a tablet and, hence, tabletability. Using a series of alkali halides with mechanical properties spanning more than one order of magnitude, the role of compaction pressure and mechanical properties on tabletability is systematically investigated and explained using the BA-BS interplay. Results reveal that BA dominates the BA-BS interplay at low pressures, where more plastic powders attain higher tensile strength due to larger BA. In contrast, BS dominates the interplay at high pressures, when difference in BA between powders is minimized. Under the typical compaction pressures of 100-300 MPa, tablet tensile strength is the highest for materials with intermediate hardness, or plasticity, due to an optimal BA-BS interplay.

Molecular complexes of drug combinations: A review of cocrystals, salts, coamorphous systems and amorphous solid dispersions

As the advancements in the medical technology and healthcare develop through the years, combinational therapy has evolved to be an important treatment modality in many disease settings, including cancer, cardiovascular disease and infectious diseases. In an effort to alleviate "pill burden" and improve patient compliance, fixed dose combinations (FDCs) have been developed to be used as effective therapeutics. Among all FDCs, the category of drug-drug molecular complexes has been proven an efficient methodology in designing and treating diseases, with many drugs being approved. Among all drug-drug molecular complexes, drug-drug cocrystals, salts, coamorphous systems and solid dispersions have been successfully developed and many have been approved by the FDA. In this review, we dwell deeply into the molecular mechanisms behind the different types of drug-drug molecular complexes, including the key functional groups involved in the intermolecular interactions, the applications of each category of molecular complexes, as well as the advantages and challenges thereof. This comprehensive review provides useful insights into the practical design and manufacture of drug-drug molecular complexes and points out the future direction for the development of new advantageous combinational therapies that benefit more patients.

Reviewing the Impact of Powder Cohesion on Continuous Direct Compression (CDC) Performance

The pharmaceutical industry is undergoing a paradigm shift towards continuous processing from batch, where continuous direct compression (CDC) is considered to offer the most straightforward implementation amongst powder processes due to the relatively low number of unit operations or handling steps. Due to the nature of continuous processing, the bulk properties of the formulation will require sufficient flowability and tabletability in order to be processed and transported effectively to and from each unit operation. Powder cohesion presents one of the greatest obstacles to the CDC process as it inhibits powder flow. As a result, there have been many studies investigating potential manners in which to overcome the effects of cohesion with, to date, little consideration of how these controls may affect downstream unit operations. The aim of this literature review is to explore and consolidate this literature, considering the impact of powder cohesion and cohesion control measures on the three-unit operations of the CDC process (feeding, mixing, and tabletting). This review will also cover the consequences of implementing such control measures whilst highlighting subject matter which could be of value for future research to better understand how to manage cohesive powders for CDC manufacture.

Polymorphs with Remarkably Distinct Physical and/or Chemical Properties

Polymorphism in crystals is known since 1822 and the credit goes to Mitscherlich who realized the existence of different crystal structures of the same compound while working with some arsenate and phosphate salts. Later on, this phenomenon was observed also in organic crystals. With the advent of different technologies, especially the easy availability of single crystal XRD instruments, polymorphism in crystals has become a common phenomenon. Almost 37 % of compounds (single component) are polymorphic to date. As the energies of the different polymorphic forms are very close to each other, small changes in crystallization conditions might lead to different polymorphic structures. As a result, sometimes it is difficult to control polymorphism. For this reason, it is considered to be a nuisance to crystal engineering. It has been realized that the property of a material depends not only on the molecular structure but also on its crystal structure. Therefore, it is not only of interest to academia but also has widespread applications in the materials science as well as pharmaceutical industries. In this review, we have discussed polymorphism which causes significant changes in materials properties in different fields of solid-state science, such as electrical, magnetic, SHG, thermal expansion, mechanical, luminescence, color, and pharmaceutical. Therefore, this review will interest researchers from supramolecular chemistry, materials science as well as medicinal chemistry.

A novel soluble lornoxicam-sodium chelate monohydrate with improved plasticity and tabletability

Lornoxicam (LOR), a BCS Ⅱ nonsteroidal anti-inflammatory drug, has been clinically utilized for moderate to severe acute pain management. However, it has poor water solubility and insufficient tabletability, leading to erratic absorption and challenge in tablet processability. This study reported a novel solid state of LOR (i.e., LOR sodium chelate monohydrate, LOR-Na·H₂O) with significantly improved solubility, dissolution rate and tabletability. The prepared chelate (CCDC No.: 2125157) contains LOR^-, Na⁺, and H₂O in a molar ratio of 1:1:1, where Na⁺ ions bridged with O(5) of amide group, and N(2) of pyridine group on LOR^-, as well as O(4) on H₂O through coordination bonds. LOR-Na·H₂O displayed a superior dissolution rate (5∼465 folds) than commercial LOR due to its increased wettability (contact angle: 74.5° vs 85.6°) and lower solvation free energy (∼2-fold). In addition, the significant improvement in tabletability was caused by high plasticity and deformability, which was attributed to its special interlayer gliding with weak bonding interactions across layers but strong coordination bonding interactions within layers. The novel LOR-Na·H₂O with significantly enhanced pharmaceutical performance offers a promising strategy for further product development.

Recent advances in drug polymorphs: Aspects of pharmaceutical properties and selective crystallization

Drug polymorphism, an established term used to describe the phenomenon that a drug can exist in different crystalline phases, has attracted great interests in pharmaceutical field in consideration of its important role in affecting the pharmaceutical performance of oral formulations. This paper presents an overview of recent advances in the research on polymorphic drug systems including understandings on nucleation, crystal growth, dissolution, mechanical properties, polymorphic transformation, etc. Moreover, new strategies and mechanisms in the control of polymorphic forms are also highlighted in this review. Furthermore, challenges and trends in the development of polymorphic drugs are briefly discussed, aiming at developing effective and efficient pharmaceutical formulations containing the polymorphic drugs.

Molecular modeling and nonlinear optical properties of new isostructural halogenated dihydroquinolinones

Two new isostructural halogenated dihydroquinolinones were synthesized and characterized by single crystal X-ray diffraction.

Puerarin-Na Chelate Hydrate Simultaneously Improves Dissolution and Mechanical Behavior

Puerarin monohydrate (PUEM), as the commercial solid form of the natural anti-hypertension drug puerarin (PUE), has low solubility, poor flowability, and mechanical properties. In this study, a novel solid form as PUE-Na chelate hydrate was prepared by a reactive crystallization method. Crystal structure analysis demonstrated that PUE-Na contains PUE^-, Na⁺, and water in a molar ratio of 1:1:7. It crystallizes in the monoclinic space group P2₁, and Na⁺ is linked with PUE^- and four water molecules through Na⁺ ← O coordination bonds. Another three crystal water molecules occupy channels along the crystallographic b-axis. Observing along the b-axis, the crystal structure features a distinct tubular helix and a DNA-like twisted helix. The complexation between Na⁺ and PUE^- in aqueous solution was confirmed by the Na⁺ selective electrode, indicating that PUE-Na chelate hydrate belongs to a type of chelate rather than organic metal salt. Compared with PUEM, PUE-Na exhibited a superior dissolution rate (i.e., ∼38-fold increase in water) owing to its lower solvation free energy and clear-enriched exposed polar groups. Moreover, PUE-Na enhanced the tabletability and flowability of PUEM, attributing to its better elastoplastic deformation and lower-friction crystal habit. The unique PUE-Na chelate hydrate with significantly enhanced pharmaceutical properties is a very promising candidate for future product development of PUE.

Role of surface molecular environment and amorphous content in moisture sorption behavior of milled Terbutaline Sulphate

Milling may cause undesired changes in crystal topology, due to exposure of new facets, their corresponding functional groups and surface amorphization. This study investigated effect of milling induced surface amorphous content and chemical environment on moisture sorption behavior of a model hydrophilic drug, Terbutaline Sulphate (TBS). A Dynamic Vapor Sorption (DVS) based analytical method was developed to detect amorphous content, with LOD and LOQ of 0.41% and 1.24%w/w, respectively. The calibration curve gave a linear regression of 0.999 in a concentration range of 0-16.36%w/w amorphous content plotted against surface area normalized % weight change, due to moisture sorption. TBS was milled using air jet mill at 8 Bars for 3 cycles (D₉₀- 3.46µm) and analyzed using the validated DVS method prior to and post conditioning. The moisture sorption was higher in case of milled unconditioned TBS. Molecular Dynamics Simulation (MDS) was performed to identify the cause for increased moisture sorption due to altered surface environment or amorphous content. The results implied that the new planes and functional groups exposed on milling had negligible contribution to moisture sorption and the higher moisture sorption in milled unconditioned TBS was due to surface amorphization. Conditioning under elevated humidity recrystallized the milling-induced surface amorphous content and led to decreased moisture sorption in milled conditioned TBS.

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.

Novel Polymorph of Favipiravir-An Antiviral Medication

Various solid forms of pharmaceutically important compounds exhibit different physical properties and bioactivity; thus, knowledge of the structural landscape and prediction of spontaneous polymorph transformations for an active pharmaceutical ingredient is of practical value for the pharmaceutical industry. By recrystallization from ethyl acetate, a novel polymorph of 6-fluoro-3-hydroxypyrazine-2-carboxamide (trademark favipiravir, RNA polymerase inhibitor) was obtained and characterized using differential scanning calorimetry (DSC), infra-red spectroscopy and powder X-ray diffraction (XRD) analysis. The favipiravir molecule in two polymorphs realizes similar H-bonding motifs, but the overall H-bonded networks differ. Based on periodic density functional theory calculations, the novel tetragonal polymorph with two interpenetrated H-bonded networks is slightly less stable than the orthorhombic one with the zst topology of the underlying H-bonded net that is in accord with experimentally observed powder XRD patterns of slow conversion of the tetragonal phase to the orthorhombic one. However, topological analysis of net relations revealed that no transformations can be applied to convert H-bonded networks in the experimental unit cells, and DSC data indicate no solid-state reactions at heating.

Structure–property correlations in piracetam polytypes

Analysis of piracetam polytypes using energy-vector models, thermal expansion and nanoindentation measurements, produces a plausible link between their crystal structures and tableting behaviour.

The Role of Cocrystallization-Mediated Altered Crystallographic Properties on the Tabletability of Rivaroxaban and Malonic Acid

The present work aims to understand the crystallographic basis of the mechanical behavior of rivaroxaban-malonic acid cocrystal (RIV-MAL Co) in comparison to its parent constituents, i.e., rivaroxaban (RIV) and malonic acid (MAL). The mechanical behavior was evaluated at the bulk level by performing “out of die” bulk compaction and at the particle level by nanoindentation. The tabletability order for the three solids was MAL < RIV < RIV-MAL Co. MAL demonstrated “lower” tabletability because of its lower plasticity, despite it having reasonably good bonding strength (BS). The absence of a slip plane and “intermediate” BS contributed to this behavior. The “intermediate” tabletability of RIV was primarily attributed to the differential surface topologies of the slip planes. The presence of a primary slip plane (0 1 1) with flat-layered topology can favor the plastic deformation of RIV, whereas the corrugated topology of secondary slip planes (1 0 2) could adversely affect the plasticity. In addition, the higher elastic recovery of RIV crystal also contributed to its tabletability. The significantly “higher” tabletability of RIV-MAL Co among the three molecular solids was the result of its higher plasticity and BS. Flat-layered topology slip across the (0 0 1) plane, the higher degree of intermolecular interactions, and the larger separation between adjacent crystallographic layers contributed to improved mechanical behavior of RIV-MAL Co. Interestingly, a particle level deformation parameter H/E (i.e., ratio of mechanical hardness H to elastic modulus E) was found to inversely correlate with a bulk level deformation parameter σ₀ (i.e., tensile strength at zero porosity). The present study highlighted the role of cocrystal crystallographic properties in improving the tabletability of materials.

Mechanochemical cocrystallization to improve the physicochemical properties of chlorzoxazone

Cocrystals of chlorzoxazone prepared by mechanochemical cocrystallization with picolinic acid to improve the physicochemical properties.

Revealing the Role of Structural Features in Bulk Mechanical Performance of Ternary Molecular Solids of Isoniazid

Mechanical performance in ternary (3n) molecular solids has been rarely studied, and hence it is an interesting topic of investigation in the direct compression method of tableting. The structural features of 3n-eutectic (3n-Eu: INZ-ADP-NIC) and 3n-cocrystal (3n-Co: INZ:SUC:NIC) were explored to understand the bonding area-bonding strength (BA-BS) interplay. Higher compressibility and lower values of the Heckel parameter of 3n-Co as compared to 3n-Eu suggested its better deformation behavior, with BA being the predominant factor. The higher tensile strength and Walker analysis indicated a higher compressibility coefficient ( W) and lower pressing modulus ( L) for 3n-Eu, which was consistent with its better tabletability over 3n-Co. The higher compressibility and plastic energy, and higher value of L of 3n-Co, were attributed to the facile propagation (⟨-1' 0' 5'⟩) of the shearing molecular slip (-1 0 5) when subjected to the external mechanical stress. Thus, the overall higher tableting performance of 3n-Eu over 3n-Co was found due to the predominant BS and limited contribution of BA. The latter was the dominant factor in 3n-Co. Cohesive interactions, like the 3D mechanically interlocked structure of conglomerates of 3n-Eu, contributed toward the higher BS. Moreover, the prediction of better tabletability solely based on crystallographic feature slip planes (0D/1D/2D H-bonded layer (h k l) ⊥ vdW interactions) is warranted in pharmaceutical molecular solids. Eutectics with varying microstructural variants ( nL_α + nL_β + nL_γ) may open up the opportunity to manipulate the physicomechanical performance.

Relating the tableting behavior of piroxicam polytypes to their crystal structures using energy-vector models

Piroxicam crystallises into two polytypes, α₁ and α_2, with crystal structures that contain identical molecular layers but differ in the way that these layers are stacked. In spite of having close structural similarity, the polytypes have significantly different powder tabletting behaviour: α₂ forms only weak tablets at low pressures accompanied by extensive capping and lamination, which make it impossible to form intact tablets above 100 MPa, while α₁ exhibits superior tabletability over the investigated pressure range (up to 140 MPa). The potential structural origin of the different behaviour is sought using energy-vector models, produced from pairwise intermolecular interaction energies calculated using the PIXEL method. The analysis reveals that the most stabilising intermolecular interactions define columns in both crystal structures. In α₂, a strongly stabilising interaction between inversion-related molecules links these columns into a 2-D network, while no comparable interaction exists in α₁. The higher dimensionality of the energy-vector model in α₂ may be one contributor to its inferior tabletability. A consideration of probable slip planes in the structures identifies regions where the benzothiazine groups of the molecules meet. The energy-vector models in this region are geometrically similar for both structures, but the interactions are more stabilising in α₂ compared to α₁. This feature may also contribute to the inferior tabletability of α₂.

Molecular Understanding and Implication of Structural Integrity in the Deformation Behavior of Binary Drug-Drug Eutectic Systems

In eutectic, a lamellar microstructure offers better tableting than that of the nonreacted physical mixture. However, bulk deformation remains elusive in two binary eutectics. We hypothesized that the binary eutectic of a drug with different components, having different H-bonding dimensionalities and crystal structure, shall allow the understanding of the structural integrity in the bulk deformation behavior. The shearing molecular solid (FXT Q) shared a common composition with the viscoelastic crystal (ASP I) and brittle (PCM I), forming EM-1 (ϕ₁ = 41.27:58.73% w/w) and EM-2 (ϕ₂ = 41.10:58.90% w/w), respectively. The excess thermodynamic functions were contributed by high energy microstructures (nonbonding interactions) along incoherent phase boundaries (visualized under CLSM). The energy dispersive analysis enabled the recognition of the relative distribution of higher atoms over the heterogeneous surface. EM-1 (FXT Q-ASP I) demonstrated higher compressibility, tensile strength, and compactibility (CTC profile) compared to those of EM-2 (FXT Q-PCM I) over a range of applied compaction pressures. The lower true yield strength (σ_0(EM-1) = 138.66 MPa) of EM-1 as compared to that of EM-2 (σ_0(EM-2) = 166.66 MPa) suggested a better deformation performance and incipient plasticity quantified from the "out-of-die" Heckel analysis. From Ryshkewitch analysis, the tensile strength at zero porosity (τ₀₁ = 3.83 MPa) was predicted to be higher for EM-1 than EM-2 (τ₀₂ = 2.54 MPa). The higher bonding strength of EM-1 was contributed to the additional influence of true density and isotropic van der Waals interactions of ASP I (0D). In contrast, EM-2 demonstrated lower compressibility and compactibility, having herringbone molecular packing of PCM I (1D) with a common shearing component (FXT Q (1D)). This study confirmed that the intrinsic deformational and chemical nature of the second component defined the compressibility and compactibility tendency to a greater extent in the tableting performance of conglomerates of crystalline solid solution.

Development and Optimization of a Starch-Based Co-processed Excipient for Direct Compression Using Mixture Design

The development of novel excipients with enhanced functionality has been explored using particle engineering by co-processing. The aim of this study was to improve the functionality of tapioca starch (TS) for direct compression by co-processing with gelatin (GEL) and colloidal silicon dioxide (CSD) in optimized proportions. Design of Experiment (DoE) was employed to optimize the composition of the co-processed excipient using the desirability function and other supporting studies as a basis for selecting the optimized formulation. The co-processed excipient (SGS) was thereafter developed by the method of co-fusion. Flow and compaction studies of SGS were carried out in comparison to its parent component (TS) and physical mixture (SGS-PM). Tablets were prepared by direct compression (DC) containing ibuprofen (200 mg) as a model for poor compressibility using SGS, Prosolv®, and StarLac® as multifunctional excipients. The optimized composition of SGS corresponded to TS (90%), GEL (7.5%), and CSD (2.5%). The functionality of SGS was improved relative to SGS-PM in terms of flow and compression. Tablets produced with SGS were satisfactory and conformed to USP specifications for acceptable tablets. SGS performed better than Prosolv® in terms of disintegration and was superior to StarLac with respect to tensile strength and disintegration time. The application of DoE was successful in optimizing and developing a starch-based co-processed excipient that can be considered for direct compression tableting.

Crystal and Particle Engineering Strategies for Improving Powder Compression and Flow Properties to Enable Continuous Tablet Manufacturing by Direct Compression

Continuous manufacturing of tablets has many advantages, including batch size flexibility, demand-adaptive scale up or scale down, consistent product quality, small operational foot print, and increased manufacturing efficiency. Simplicity makes direct compression the most suitable process for continuous tablet manufacturing. However, deficiencies in powder flow and compression of active pharmaceutical ingredients (APIs) limit the range of drug loading that can routinely be considered for direct compression. For the widespread adoption of continuous direct compression, effective API engineering strategies to address power flow and compression problems are needed. Appropriate implementation of these strategies would facilitate the design of high-quality robust drug products, as stipulated by the Quality-by-Design framework. Here, several crystal and particle engineering strategies for improving powder flow and compression properties are summarized. The focus is on the underlying materials science, which is the foundation for effective API engineering to enable successful continuous manufacturing by the direct compression process.

Relationship between mechanical properties and crystal structure in cocrystals and salt of paracetamol

Objectives were to study mechanical properties of various solid forms of paracetamol and relate to their crystal structures. Paracetamol form I (PRA), its cocrystals with oxalic acid (PRA-OXA) and 4,4-bipyridine (PRA-BPY) and hydrochloride salt (PRA-HCL) were selected. Cocrystals and salt were scaled-up using rational crystallization methods. The resulting materials were subjected to different solid-state characterizations. The powders were sieved and 90-360 µm sieve fraction was considered. These powders were examined by scanning electron microscopy (SEM) and densities were determined. Tablets were made at applied pressures of 35-180 MPa under controlled conditions and the tablet height, diameter and hardness were measured. Tensile strength and porosity of the tablets were estimated using well known models. Crystal structures of these systems were visualized and slip planes were identified. Cocrystal and salt of PRA were physically pure. Sieved powders had comparable morphologies and particle size. The apparent and theoretical densities of powders were similar, but no clear trends were observed. The tensile strengths of these compacts were increased with increasing pressure whereas tabletability decreased in the order oxalic acid > PRA-HCL ≈ PRA-OXA > BPY > PRA-BPY. Tablet tensile strength decreases exponentially with increasing porosity with the exception of PRY-BPY and BPY. Slip plane prediction based on attachment energies may not be independently considered. However, it was possible to explain the improved mechanical properties of powders based on the crystal structure. Cocrystallization and salt formation have introduced structural features that are responsible for improved tableting properties of PRA.

Visualization and quantification of deformation behavior of clopidogrel bisulfate polymorphs during tableting

The deformation behavior of particles under pressure dominates the mechanical properties of solid dosage forms. In this study, the in situ 3D deformation of two polymorphs (I and II) of clopidogrel bisulfate (CLP) was determined to illustrate pressure distribution profiles within the tablet by the deformation of the crystalline particles for the first time. Synchrotron radiation X-ray computed microtomography (SR-μCT) was utilized to visualize and quantify the morphology of thousands crystalline particles of CLP I and CLP II before and after compression. As a result, the deformation was examined across scale dimensions from microns to the size of the final dosage form. Three dimensional parameters such as volume, sphericity, oblate and prolate of individual particle and distributions were computed and analyzed for quantitative comparison to CLP I and CLP II. The different degrees of deformation under the same compression conditions of CLP I and CLP II were observed and characterized quantitatively. The map of deformation degrees within the tablet illustrated the heterogeneous pressure distribution in various regions of the compacted tablet. In conclusion, the polymorph deformation behaviors demonstrated by SR-μCT quantitative structure analysis deepen understanding of tableting across dimensions from microns to millimeters for the macrostrcuture of tablet.

The solid-state continuum: a perspective on the interrelationships between different solid-state forms in drug substance and drug product

Objective

The objective of the review is to provide an overview of the nomenclature used in the solid-state continuum and relate these to the development of drug substances and drug products.

Key findings

The importance of a rational approach to solid-state form selection, including integrated decision making (ensuring equal weight is given to the needs of the drug substance and the drug product), is vital for the effective development of a drug candidate. For example, how do secondary processing considerations influence the selection of drug substance solid-state form and resulting formulation, and how can drug substance solid-state form be used to optimise secondary processing? Further, the potential use of ‘crystal’ engineering to optimise stability, purity and optical resolutions, and the linked regulatory requirements, will be discussed.

Summary

The nomenclature used in the solid-state continuum, which contains a large number of different crystalline and non-crystalline forms, for example, amorphous systems, was reviewed. Further, the significant role of the drug substance within the solid oral dose form from a physicochemical perspective was covered.

Differential compaction behaviour of roller compacted granules of clopidogrel bisulphate polymorphs

In the present work, in-die and out-of-die compaction behaviour of dry-granulated powders of clopidogrel bisulphate (CLP) polymorphs, form I and form II, was investigated using a fully instrumented rotary tablet press. Each polymorph was compacted at three different roller pressures [70.3 (S1), 105.5 (S2) and 140.6 (S3)kgf/cm(2)], and obtained granules were characterized for their physico-mechanical properties. Compaction data were analyzed for out-of-die compressibility, tabletability and compactibility profiles, and in-die Heckel, Kawakita and Walker analysis. The roller compacted granules of both forms showed markedly different tabletting behaviour. Roller pressure exhibited a trend on compaction behaviour of form I granules, whereas, in case of form II, the effect was insignificant. Tabletability of the six granule batches follows the order; I_S1>I_S2>I_S3>II_S1≈II_S2≈II_S3. In case of form I, the reduced tabletability of the granules compacted at higher roller pressure was attributed to the decreased compressibility and plastic deformation. This was confirmed by compressibility plot and various mathematical parameters derived from Heckel (Py), Kawakita (1/b) and Walker (W) equations. The reduced tabletability of form I granules was due to 'granule hardening' during roller compaction. On the other hand, insignificant effect of roller compaction on tabletting behaviour of form II granules was attributed to brittle fragmentation. The extensive fragmentation of granules offered new 'clean' surfaces and higher contact points that negated the effect of granule hardening.

Implication of microstructure on the mechanical behaviour of an aspirin–paracetamol eutectic mixture

The present work investigates the mechanical behaviour of an aspirin–paracetamol (ASP–PCM) eutectic mixture (EM).

Effect of particle size on in-die and out-of-die compaction behavior of ranitidine hydrochloride polymorphs

The present study investigates the effect of particle size on compaction behavior of forms I and II of ranitidine hydrochloride. Compaction studies were performed using three particle size ranges [450-600 (A), 300-400 (B), and 150-180 (C) μm] of both the forms, using a fully instrumented rotary tableting machine. Compaction data were analyzed for out-of-die compressibility, tabletability, and compactibility profiles and in-die Heckel and Kawakita analysis. Tabletability of the studied size fractions followed the order; IB > IA > > IIC > IIB > IIA at all the compaction pressures. In both the polymorphs, decrease in particle size improved the tabletability. Form I showed greater tabletability over form II at a given compaction pressure and sized fraction. Compressibility plot and Heckel and Kawakita analysis revealed greater compressibility and deformation behavior of form II over form I at a given compaction pressure and sized fraction. Decrease in particle size increased the compressibility and plastic deformation of both the forms. For a given polymorph, improved tabletability of smaller sized particles was attributed to their increased compressibility. However, IA and IB, despite poor compressibility and deformation, showed increased tabletability over IIA, IIB, and IIC by virtue of their greater compactibility. Microtensile testing also revealed higher nominal fracture strength of form I particles over form II, thus, supporting greater compactibility of form I. Taken as a whole, though particle size exhibited a trend on tabletability of individual forms, better compactibility of form I over form II has an overwhelming impact on tabletability.