Compaction behavior and deformation mechanism of directly compressible textured mannitol in a rotary tablet press simulator

Critical review on the role of excipient properties in pharmaceutical powder-to-tablet continuous manufacturing

INTRODUCTION

The pharmaceutical industry is gradually changing batch-wise manufacturing processes to continuous manufacturing processes, due to the advantages it has to offer. The final product quality and process efficiency of continuous manufacturing processes is among others impacted by the properties of the raw materials. Existing knowledge on the role of raw material properties in batch processing is however not directly transferable to continuous processes, due to the inherent differences between batch and continuous processes.

AREAS COVERED

A review is performed to evaluate the role of excipient properties for different unit operations used in continuous manufacturing processes. Unit operations that will be discussed include feeding, blending, granulation, final blending, and compression.

EXPERT OPINION

Although the potency of continuous manufacturing is widely recognized, full utilization still requires a number of challenges to be addressed effectively. An expert opinion will be provided that discusses those challenges and potential solutions to overcome those challenges. The provided overview can serve as a framework for the pharmaceutical industry to push ahead process optimization and formulation development for continuous manufacturing processes.

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

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

Rational Design and Development of a Soluble Mesoporous Carrier for the Solidification of a Preconcentrated Self-Nanoemulsion Formulation

The solidification of self-preconcentrated nanoemulsion without changes in nanodroplet formation gains particular consideration due to the interaction between solidified carriers. This work aimed to develop mannitol mesoporous as a soluble carrier for supersaturated self-nanoemulsion (SSNE) using a design of experiment (DoE) approach. The mesoporous carrier was prepared by a spray-drying technique. The type of templating agent (TA) used to form a porous system, the amount of TA, and solid loading in the spray-drying process were studied. Several characterizations were performed for mannitol mesoporous formation, namely, powder X-ray diffraction, thermal analysis, scanning electron microscopy, and surface area analyzer. Solidification of SSNE incorporated into the mesoporous mannitol was carried out, followed by compaction behavior, flowability, and nanodroplet formation. The results revealed several process parameters for preparing the mesoporous mannitol, notably TA, which gained more significant consideration. Solid loading in the mesoporous preparation system reduced the surface area and pore size and did not affect solid SSNE flowability. The amount of TA increased the pore size and volume dramatically as well as the compactibility and flowability. Ammonium carbonate was the preferable TA for preparing the mesoporous carrier, particularly for the nanodroplet formulation process. In addition, synergistic and antagonistic interactions between factors were also observed. The optimized mesoporous carrier was applied for solidification, and there was no difference between SSNE and solid SSNE in the performance of nanodroplet formation.

Screening of lubricants towards their applicability for external lubrication

Internal lubrication is associated with decreasing tensile strength and prolonged disintegration. These effects can be minimized using external lubrication. In current study, six lubricants (magnesium stearate, sodium stearyl fumarate, stearic acid, glyceryl dibehenate, poloxamer 188 and sucrose monopalmitate) were processed with an external lubrication system implemented in a compaction simulator. The effect of process parameters related to the tableting process (main compaction pressure and tableting speed) and external lubrication system (spraying time, atomizing pressure and dust extraction system) on the responses was studied for a placebo formulation (80% mannitol - 20% microcrystalline cellulose). Internally lubricated blends (0.75 - 4%) were processed as reference. All lubricants proved successful in reducing ejection forces through external lubrication while yielding substantially lower lubricant concentrations compared to internal lubrication. No negative effect of external lubrication on tensile strength and disintegration time was observed, irrespective of lubricant type. Similar tensile strengths and disintegration times were measured for the different lubricants. This was in contrast to internal lubrication where a decrease in tensile strength and prolonged disintegration was generally observed. Additionally, the lubricant types affected tensile strength and disintegration differently. This study demonstrates the versatility of external lubrication as an alternative lubrication method for production of pharmaceutical tablets.

Continuous measurement of die wall pressure in a rotary tablet machine

In the pharmaceutical industry, tablets are manufactured using rotary tableting machines. Recently, die wall pressure in a single-punch press was measured to understand the compaction mechanism and predict tableting failure. However, die wall pressure measurements in rotary tableting machines have not been studied. Two challenges exist in measuring die wall pressure in these machines, viz. (i) lack of space inside the machine to set up the measurement equipment and (ii) difficulty in installing wired measurement hardware because the die rotates with the rotary plate. This study aimed to continuously measure die wall pressure in a rotary tableting machine and investigate the effect of high compression speed on die wall pressure. Die wall pressure at tableting speeds of up to 140 mm/s was successfully determined using a wireless telemeter. Residual die wall pressure for plastic materials was strongly dependent on the tableting speed, although the tableting speed affected the maximum die wall pressure minimally. This novel measurement technique can be used to study the effect of tableting speed on die wall pressure, which can be applied in solving the problems of capping and lamination during tablet production.

Impact of alternative lubricants on process and tablet quality for direct compression

Internal lubrication with magnesium stearate (MgSt) is associated with a reduced tensile strength and prolonged disintegration and dissolution times. In the current study, alternative lubricants to MgSt were compared with regard to lubrication efficacy and their impact on tablet properties. The lubricants were combined in different concentrations (0.5-5% w/w) with three fillers (lactose, mannitol and microcrystalline cellulose (MCC)). The high lubrication efficiency of MgSt was associated with the highest reduction of tensile strength. The micronized stearic acid (SA) grades proved good alternatives as they showed a good lubrication efficiency in combination with a limited negative effect on tensile strength. The hydrophobic lubricants (e.g., MgSt and SA) did not prolong disintegration. In contrast, delayed disintegration was observed for sucrose monopalmitate combined with all three fillers and for several other hydrophilic lubricants (sodium lauryl sulfate, poloxamers 188 and P407) combined with MCC. These unexpected findings were explained by the competition-for-water hypothesis. The potential of alternative lubricants to MgSt was demonstrated in this study. Nevertheless, the impact of lubricant addition on process and tablet quality depended on lubricant (type and concentration) and formulation (lubrication need, deformation mechanism and disintegration behavior) properties. Therefore, lubricant selection should be carefully considered in formulation development.

Effect of feed frame on lubricant sensitivity during upscaling from a compaction simulator to a rotary tablet press

Internal lubrication can be associated with reduced tabletability. Deformation mechanism, lubricant type, lubricant blending time and paddle speed (PS) of the forced feeder are known to be influenceable factors. This study investigated the effect of lubricant blending time and PS of forced feeders on the tensile strength of lubricated microcrystalline cellulose (MCC) and lactose tablets. Magnesium stearate (MgSt), sodium stearyl fumarate (SSF) and stearic acid (SA) were used as lubricants. Tablets were produced on a compaction simulator and a rotary tablet press to investigate lubricant sensitivity during upscaling. Lubricant sensitivity was found higher for MCC compared to lactose which was attributed to the higher plasticity of MCC. The reduction in tensile strength upon lubricant addition followed the order: MgSt > SSF > SA; which could be linked to particle size, specific surface area and particle shape of the lubricants. Although differences in tensile strength were observed between the lubricant types, comparable ejection forces were obtained. The impact of PS on tensile strength was higher compared to lubricant blending time for both tableting machines. A good correlation of tensile strength and lubricant sensitivity between the compaction simulator and rotary tablet press was observed based on the calculation of paddle passes (N_PP).

Formulation and Characterization of an Effervescent Hydrogen-Generating Tablet

Hydrogen, as a medical gas, is a promising emerging treatment for many diseases related to inflammation and oxidative stress. Molecular hydrogen can be generated through hydrogen ion reduction by a metal, and magnesium-containing effervescent tablets constitute an attractive formulation strategy for oral delivery. In this regard, saccharide-based excipients represent an important class of potential fillers with high water solubility and sweet taste. In this study, we investigated the effect of different saccharides on the morphological and mechanical properties and the disintegration of hydrogen-generating effervescent tablets prepared by dry granulation. Mannitol was found to be superior to other investigated saccharides and promoted far more rapid hydrogen generation combined with acceptable mechanical properties. In further product optimization involving investigation of lubricant effects, adipic acid was selected for the optimized tablet, due to regulatory considerations.

Investigating key properties of model excipients and binary powder blends using ultrasonic in-die measurements on a compaction simulator

In this work, the recently introduced Kilian Inline Measurement System (KIM) that enables ultrasonic measurements during powder compaction was studied using three pharmaceutical excipients with different properties and particle sizes, applying various amounts of lubricant and different compaction pressures. It was shown that the generated results were highly reproducible, not only in series but also on different days including dismantling and reassembling of the components. The relation between ultrasonic velocity and increasing compact density differed among the investigated materials and was independent of initial particle size and applied maximum pressure. Since the velocity through a porous solid is dependent on pore volume and shape, velocity profiles have the potential to track changes in the microstructures of the materials. Furthermore, ultrasonic velocities through binary mixtures (50:50 (w/w)) at a given solid fraction were between the values of the plain excipients, but more closely resembled one of their components. This may be indicative of the compaction behavior and performance of the blend. Overall, ultrasonic instrumentation seems to be a robust and promising tool for the characterization of powders and blends in compaction processes. However, its practical value must still be investigated further including multi-component blends, underlying densification mechanisms, and decompression.

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.

Development of Pediatric Orodispersible Tablets Based on Efavirenz as a New Therapeutic Alternative

BACKGROUND

Efavirenz is the most used medication in the treatment of Acquired Immunodeficiency Syndrome (AIDS). The limited number of pediatric antiretroviral formulations approved by regulatory agencies is the most significant obstacle to adequate and efficient pharmacotherapy for this group of patients. The efavirenz has excellent therapeutic potential, but has low aqueous solubility/bioavailability.

METHODS

To minimize these limitations, multicomponent systems with β-cyclodextrin and polyvinylpyrrolidone K-30 were obtained. Due to the limited number of pediatric antiretroviral formulations, the development of a pediatric orodispersible tablet is an alternative that is thought easy to administer, since it disintegrates rapidly in the oral cavity. The multicomponent systems were obtained by the method of kneading and characterized by solubility test, X-ray diffraction, differential scanning calorimetry and infrared absorption spectroscopy by Fourier transform. The orodispersible tablets were prepared by direct compression. The quality control of hardness, friability, disintegration, and dissolution was performed. The influence of the components of the formulation on the characteristics of the tablets was evaluated through a 22 factorial design added with three central points, to compare the effect of the dependent variables on the responses.

RESULTS

An increase in drug solubility was observed, with a decrease in crystallinity. Besides that, an excellent dissolution profile presented with more than 83% of the drug's content dissolved in less than 15 minutes. Satisfactory disintegration time and friability were observed.

CONCLUSION

It was observed that reduced concentrations of mannitol decreased the hardness and disintegration time of the formulations. The orodispersible tablet composed of efavirenz: β- cyclodextrin: polyvinylpyrrolidone, favors greater absorption and bioavailability. It has several advantages for pediatric patients, as the dosage form disintegrates quickly in the mouth and does not require water for administration, thereby improving patient compliance with the treatment.

Scaling Tableting Processes from Compaction Simulator to Rotary Presses-Mind the Sub-Processes

Compaction simulators are frequently used in the formulation and process development of tablets, bringing about the advantages of flexibility, low material consumption, and high instrumentation to generate the most possible process understanding. However, their capability of resembling general aspects of rotary press compaction and their precision in simulating or mimicking sub-processes such as feeding and filling need to be systematically studied. The effect of material deformation behavior, blend composition, and feeding on tensile strength and simulation precision as compared with rotary presses of different scales is evaluated in this study. Generally, good simulation performance was found for the studied compaction simulator. Compaction profile-sensitivity was demonstrated for highly visco-plastic materials while shear-sensitivity in feeding was demonstrated for lubricated blends of ductile particles. Strategies for the compensation of both in compaction simulator experiments are presented by careful investigation of the compaction stress over time profiles and introduction of a compaction simulator-adapted shear number approach to account for differences in layout and operation mode between compaction simulator and rotary press, respectively. These approaches support the general aim of this study to provide a more straightforward determination of scaling process parameters between rotary press and compaction simulator and facilitate a quicker and more reliable process transfer.

Structure-Properties Relationship in the Evaluation of Alginic Acid Functionality for Tableting

The aim of this study is to investigate the relationship between the structural, molecular, and particulate properties of alginic acid and its functional characteristics in direct compression (tabletability, compressibility, elasticity, deformation mechanism, and disintegration ability). Therefore, accurate characterization of two different batches of alginic acid was executed (X-ray powder diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electronic microscopy, ¹H nuclear magnetic resonance, size exclusion chromatography - multi angle light scattering, viscosimetry, carboxylic acid titration, powder flowability, true density, laser granulometry). Results showed that molecular weight seems to affect tablet properties and that the alginic acid with the lowest molecular weight provides the hardest tablets with the lowest elastic recovery. Furthermore, these results show the potential interest of exploiting alginic acid as filler excipient in tablet formulation. Finally, disintegration properties of tested materials were found to be close to that of commercial superdisintegrants (Glycolys® and Kollidon Cl®) but not correlated to their swelling force. It can be concluded, for the first time, that the determination of alginic acid molecular weight seems key for applications in direct compression and in particular for obtaining tablets with reproducible strength.

Systematic approach to elucidate compaction behavior of acyclovir using a compaction simulator

In this research, various approaches were attempted with a compaction simulator to investigate the unidentified compaction behavior of acyclovir, a model compound. Various indicators for the compaction behavior of acyclovir were obtained and compared with those of three commonly used excipients with relatively well-known compaction behavior. From two frequently used powder compaction models, the Heckel and Walker models, curvature of plot, yield stress, D₀, SRS value, and W value were acquired. In addition, compression and elastic energies were obtained during the loading and unloading phases, respectively. The ratio of the two energies was also utilized. To characterize the mechanical properties of materials during bond formation, the radial tensile strength of powder compacts was measured. For all evaluations, the effects of compaction rate and lubrication were studied simultaneously. We found that primary particles of acyclovir were compacted mainly by plastic flow, with high viscoelasticity and low particle interactions. Their bond formation was highly sensitive to strain rate and lubrication. This study showed the potential application of a compaction simulator to elucidate the compaction behavior of a material of interest.

Understanding the effect of lipid formulation loading and ethanol as a diluent on solidification of pitavastatin super-saturable SNEDDS using factorial design approach

Solidification of a preconcentrate lipid formulation namely self-nano emulsifying drug delivery system (SNEDDS) is required to achieve feasibility, flexibility, and a new concept of “dry nano-emulsion”. The purpose of this study was to assess the effect of SNEDDS loading and ethanol as a diluent on the solidification of pitavastatin supersaturable SNEDDS (S-SNEDDS). A 2² full factorial design approach with a center point addition as a curvature was implemented to determine the effect of S-SNEDDS loading and ethanol on the physical characteristics, namely flowability, compactibility, and drug release behavior. Vibrational spectra, thermal behavior, and morphology of solid S-SNEDDS formulation were also evaluated. The results indicated that there was no interaction between S-SNEDDS and carrier, based on vibrational spectra. However, thermal behaviors (enthalpy and weight loss) were depending on SNEDDS loading. Thereafter, the ethanol as a diluent of preconcentrated formulation had no effect on the morphology of carrier structure. However, the S-SNEDDS loading altered the structure of carrier owing to either solubilization or abrasion processes. The statistical model suggested that ethanol as diluent reduced the flowability, compactibility, and drug releases. Meanwhile, the liquid SNEDDS loading affected the reducing of flowability and compactibility. Finally, solidification without diluent and 20% lipid formulation load was recommended. In addition, it was very useful because of ease on handling, flexibility for further formulation, and desired characteristics of final solid dosage form.

Reducing Burst Release Effect of Freely Water-Soluble Drug Incorporated into Gastro-Floating Formulation Below HPMC Threshold Concentration Through Interpolymer Complex

Undesired-burst release effect is observed in a freely water-soluble drug formulated into a gastro-floating formulation with effervescent (GFFE) delivery system. In order to address this limitation, interpolymer complex (IPC) of two swellable and non-soluble polymers, poly-ammonium methacrylate and poly-vinyl acetate, was incorporated into hydroxypropyl methyl cellulose (HPMC)-based matrix GFFE. This research studied the effect and interaction of the IPC-HPMC blending on the drug release of GFFE using a freely water-soluble drug, metformin HCl, under different threshold concentration levels and curing effect. The interaction between the IPC and HPMC was characterized using vibrational spectroscopy and thermal analyses under curing and swelling conditions. Anti-solvent followed by lyophilization had better physicochemical and physicomechanic properties than spray dying technique. The interaction was observed by a specific shifting of the vibrational peaks and alteration of the thermal behavior pattern. These effects altered the drug release behavior. Thereafter, the IPC reduced burst release effects in the initial time and during testing, and the IPC improved the HPMC matrix robustness under mechanical stress testing below threshold concentration of HPMC matrix formulated in the GFFE.

Optimization of the Cohesion Index in the SeDeM Diagram Expert System and application of SeDeM Diagram: An improved methodology to determine the Cohesion Index

In this study, we suggest optimizing the methodology to determine the Cohesion Index (Icd) in order to avoid mistaken characterizations due to powder bulk density. For this purpose, five different excipients, with different bulk densities and of different chemical nature, were compressed at different heights. Their compression and their tablet characterization enable establishing a powder weight for compression in accordance with its bulk density. Therefore, the resulting tablet will have a height within a defined range of heights where it has no critical effects on its hardness. Then, the impact of this optimization is shown in a formula development, one of the main SeDeM's applications. A mathematical equation was used to calculate the theoretical amount of excipient to formulate the API according to both methodologies. The compression results demonstrate that the characterization with the NM-Icd is more accurate than the previous one while preserving its simplicity.

Deformation behavior of crystallized mannitol during compression using a rotary tablet press simulator

Mannitol is commonly used as a pharmaceutical excipient for tablets; the most widely used oral dosage form for drug delivery. For tableting, mannitol is provided in two different forms: native crystals and textured particles. In order to optimize its formulation, a good understanding of the mechanical behavior mechanism of mannitol is necessary. Thus, the aim of this study is to evaluate the deformation mechanism of native mannitol crystals presenting different particle sizes. Pharmaco-technical and compression studies were performed using mannitol with different mean diameters (160 µm, 50 µm and 25 µm). Lactose (monohydrate) and microcrystalline cellulose were used as brittle and plastic reference materials, respectively. Tableting tests and mathematical models, HECKEL and WALKER, were used to study the deformation mechanism of mannitol (β). Mean Yield Pressure (Py) and WALKER coefficient (W) values showed that the studied crystalline mannitol presents a deformation mechanism close to brittle material. A particle-size analyzer was used at different pulverization pressures to show the high sensibility of the mannitol particles to fragmentation when exposed to high pressures, especially for particles presenting 160 µm size. Scanning Electron Microscopy (SEM) was used to show the fragmentation after high-pressure measurements.

Bulk Freeze-Drying Milling: a Versatile Method of Developing Highly Porous Cushioning Excipients for Compacted Multiple-Unit Pellet Systems (MUPS)

The compaction of multiple-unit pellet system (MUPS) is a challenging process due to the ease of coat damage under high compression pressure, thereby altering drug release rates. To overcome this, cushioning excipients are added to the tablet formulation. Excipients can be processed into pellets/granules and freeze-dried to increase their porosity and cushioning performance. However, successful formation of pellets/granules has specific requirements that limit formulation flexibility. In this study, a novel top-down approach that harnessed bulk freeze-drying milling was explored to avoid the challenges of pelletization/granulation. Aqueous dispersions containing 20%, w/w hydroxypropyl methylcellulose (HPMC), partially pregelatinised starch or polyvinylpyrrolidone alone, and with lactose (Lac) in 1:1 ratio, were freeze-dried and then milled to obtain particulate excipients for characterization and evaluation of their cushioning performance. This study demonstrated that bulk freeze-drying milling is a versatile method for developing excipients that are porous and directly compressible. The freeze-drying process modified the materials in a unique manner which could impart cushioning properties. Compared to unprocessed excipients, the freeze-dried products generally exhibited better cushioning effects. The drug release profile of drug-loaded pellets compacted with freeze-dried Lac-HPMC excipients was similar to that of the uncompacted drug-loaded pellets (f ₂ value = 51.7), indicating excellent cushioning effects. It was proposed that the specific balance of brittle and plastic nature of the freeze-dried Lac-HPMC composite conferred greater protective effect to the drug-loaded pellets, making it advantageous as a cushioning excipient.

Application of continuous twin screw granulation for the metformin hydrochloride extended release formulation

This study focuses on evaluating the potential of transferring from a batch process to continuous process for manufacturing of the extended release formulation. Metformin hydrochloride (HCl) was used in the model formulation which was intended to contain the high amount of hydrophilic drug. The effects of barrel temperature, binder type, powder feed rate, and screw speed on granule properties (size and strength) and torque value in twin screw granulation were investigated. Due to the high content of hydrophilic model drug, the granules prepared at a higher temperature with HPMC binding solution had the narrower size distribution and greater strength than the granules prepared with distilled water as a binding solution. After continuous drying and milling steps, the granules (continuous process) satisfied the fundamental purpose of granulation with size and flowability, despite different shape compared with the granules (batch process). Furthermore, there were no significant differences between two granulation processes in tablet properties, such as tablet hardness and in vitro release. The considerations and strategies used in this study to transfer from a batch to continuous process can be applied to other existing formulations based on high shear granulation to enable rapid process transfer in the pharmaceutical industry.

Evaluation of disintegrants functionality for orodispersible mini tablets

OBJECTIVE

This work evaluates the functionalities of different superdisintegrants (SD) for manufacturing orodispersible mini tablets (ODMT) by direct compression.

METHODS

Twenty-three formulations varying in SD type, concentration, and lubricant were used to manufacture ODMT. The ODMT were then characterized for the following properties: friability, porosity, tensile strength, in vivo and in vitro disintegration time (DT).

RESULTS

The results show that the presence, type, and concentration of SD did not influence friability, porosity, or tablet tensile strength. With regards to in vivo DT, only cross-linked poly (vinyl pyrrolidone) improved DT in all the tested formulations. Results also showed that when using microcrystalline cellulose (MCC) above 20% in the formulation, DT is longer. Cross-linked carboxymethyl cellulose accelerates DT when the MCC content is less than 20%. As for cross-linked carboxymethyl starch and calcium alginate showed no improvement on DT. Results for in vitro DT were all shorter than in vivo results and there was no correlation with the in vivo evaluation.

CONCLUSIONS

This study shows that there is a need to develop better in vitro testing that precisely simulates in vivo conditions and that are adapted to ODMT. This standardization of the test methods for ODMTs must be accompanied by an improvement in the comprehension of SD mechanisms.

In-line monitoring of compaction properties on a rotary tablet press during tablet manufacturing of hot-melt extruded amorphous solid dispersions

As the number of applications for polymers in pharmaceutical development is increasing, there is need for fundamental understanding on how such compounds behave during tableting. This research is focussed on the tableting behaviour of amorphous polymers, their solid dispersions and the impact of hot-melt extrusion on the compaction properties of these materials. Soluplus, Kollidon VA 64 and Eudragit EPO were selected as amorphous polymers since these are widely studied carriers for solid dispersions, while Celecoxib was chosen as BCS class II model drug. Neat polymers and physical mixtures (up to 35% drug load) were processed by hot-melt extrusion (HME), milled and sieved to obtain powders with comparable particle sizes as the neat polymer. A novel approach was used for in-line analysis of the compaction properties on a rotary tablet press (Modul P, GEA) using complementary sensors and software (CDAAS, GEA). By combining 'in-die' and 'out-of-die' techniques, it was possible to investigate in a comprehensive way the impact of HME on the tableting behaviour of amorphous polymers and their formulations. The formation of stable glassy solutions altered the formulations towards more fragmentary behaviour under compression which was beneficial for the tabletability. Principal component analysis (PCA) was applied to summarize the behaviour during compaction of the formulations, enabling the selection of Soluplus and Kollidon VA 64 as the most favourable polymers for compaction of glassy solutions.