Direct Compression Tablet Containing 99% Active Ingredient—A Tale of Spherical Crystallization

Assessing processability of milled HME extrudates: Consolidating the effect of extrusion temperature, drug loading, and particle size via Non-dimensional cohesion

The downstream processability of Hot Melt Extrusion (HME) Amorphous Solid Dispersions (ASD), an underexplored topic of importance, was assessed through a multi-faceted particle engineering approach. Extrudates, comprised of griseofulvin (GF), a model poorly water-soluble drug, and hydroxypropyl cellulose (HPC), were prepared at four drug concentrations and three HME temperature profiles to yield cases with and without residual crystallinity and subsequently milled to five sieve cuts ranging from < 45 μm to 355 - 500 μm. Solid state characterization was performed with XRPD, FT-IR, and TGA. Particle scale properties of the milled extrudates were evaluated including particle size, density, surface energy, and morphologies imaged via SEM. It was observed that regardless of sieve cut size, drug concentration and HME conditions impacted the flowability trends, quantified via Flow Function Coefficient (FFC) and bulk density. As a novelty, the effects of various process parameters and drug loadings were consolidated into a dimensionless interparticle cohesion measure, granular Bond Number (Bog), to better correlate them with bulk powder properties. The significant contrast in particle morphologies, particle size, and densities among selected cases demonstrated that particle size alone should not be the sole consideration when correlating particle scale to bulk powder scale properties of milled extrudates. Instead, the HME temperature profile and ASD drug loading may be more suitable parameters affecting the bulk powder properties of the milled extrudates.

Enhancing flowability of lamivudine through quasi-emulsion solvent-diffusion (QESD) crystallization: A comprehensive study on surfactant impact, particle morphology by QbD concepts and tablet compression challenges

Lamivudine (LMD), an enantiomer of 2'-deoxy-3'-thiacytidine, plays a crucial role in combatting HIV-1 and managing hepatitis B virus infections. Despite its effectiveness, challenges arise from its difficult flowability and tendency to agglomerate during storage, necessitating a granulation step before tablet compression, as direct compression has proven ineffective. This study aimed to optimize Lamivudine spherical agglomerates using response surface methodology, delving into the intricate relationship between design factors (concentration of tween, span, and acetone) and experimental outcomes (yield and particle size) through central composite design. Analysis of variance (ANOVA) was employed for optimization, with the Quasi-emulsion solvent-diffusion (QESD) crystallization technique utilized for the checkpoint batch. This technique, involving a single solvent and antisolvent with surfactants, showcased remarkable enhancements in flowability and reduced storage agglomeration. The impact of various surfactants [Hydroxy Propyl Methyl Cellulose (HPMC), polysorbate 80, and sorbitane monooleate] on particle morphology, flowability, and storage agglomeration during crystallization was thoroughly assessed. While achieving direct compression into tablets, the porous structure of LMD agglomerates presented challenges in tablet press production speeds, prompting adjustments such as reducing punch speed or implementing a precompression step. Positive outcomes were realized for disintegration and in vitro drug release in comparison to direct compression and wet granulation methods. In conclusion, the QESD crystallization technique successfully yielded hollow, spherical LMD agglomerates with enhanced properties, representing a significant milestone in pharmaceutical formulation.

Facilitating direct compaction tableting of fine cohesive APIs using dry coated fine excipients: Effect of the excipient size and amount of coated silica

The possibility of attaining direct compression (DC) tableting using silica coated fine particle sized excipients was examined for high drug loaded (DL) binary blends of APIs. Three APIs, very-cohesive micronized acetaminophen (mAPAP, 7 μm), cohesive acetaminophen (cAPAP, 23 μm), and easy-flowing ibuprofen (IBU, 53 μm), were selected. High DL (60 wt%) binary blends were prepared with different fine-milled MCC-based excipients (ranging 20- 37 μm) with or without A200 silica coating during milling. The blend flowability (flow function coefficient -FFC) and bulk density (BD) of the blends for all three APIs were significantly improved by 1 wt% A200 dry coated MCCs; reaching FFC of 4.28 from 2.14, 7.82 from 2.96, and > 10 from 5.57, for mAPAP, cAPAP, and IBU blends, respectively, compared to the uncoated MCC blends. No negative impact was observed on the tablet tensile strength (TS) by using dry coated MCCs despite lower surface energy of silica. Instead, the desired tablet TS levels were reached or exceeded, even above that for the blends with uncoated milled MCCs. The novelty here is that milled and silica coated fine MCCs could promote DC tableting for cAPAP and IBU blends at 60 wt% DL through adequate flowability and tensile strength, without having to dry coat the APIs. The effect of the silica amount was investigated, indicating lesser had a positive impact on TS, whereas the higher amount had a positive impact on flowability. Thus, the finer excipient size and silica amounts may be adjusted to potentially attain blend DC processability for high DL blends of fine APIs.

Trace polymer coated clarithromycin spherulites: Formation mechanism, improvement in pharmaceutical properties and development of high-drug-loading direct compression tablets

Clarithromycin (CLA) is a high dose antibiotic drug exhibiting poor flowability and tabletability, making the tablet development challenging. This study aims to develop spherulitic CLA by introducing trace amount of polymer in crystallization solution. Its formation mechanism, physicochemical properties and potential for the direct compression (DC) tablets development were also investigated. Morphological analyses and the in situ observation on crystallization process revealed that the CLA spherulites are formed by fractal branching growth from both sides of the threadlike precursor fibers. 1H NMR analysis and nucleation time monitoring indicated that the existence of hydroxypropyl cellulose in solution slowed down the crystal nucleation and growth rate by forming hydrogen bonding interactions with CLA molecules, making the system maintain high supersaturation, providing high driving forces for CLA spherulitic growth. In comparison to commercial CLA, the CLA spherulites exhibit profoundly improved flowability, tabletability and dissolution behaviors. XPS, contact angle and Raman mapping analysis confirmed the presence of a thin HPC layer on the surfaces and interior of CLA spherulitic particles, resulting in increasing powder plasticity, interparticulate bonding strength and powder wettability, thus better tabletability and dissolution performances. The improved flowability and tabletability of CLA spherulites also enabled the successful development of DC tablet formulation with a high CLA loading (82.8 wt%) and similar dissolution profiles to reference listed drug. This study provides a novel solid form of CLA with superior manufacturability for further development.

Selection of Silica Type and Amount for Flowability Enhancements via Dry Coating: Contact Mechanics Based Predictive Approach

PURPOSE

To investigate the effect of dry coating the amount and type of silica on powder flowability enhancement using a comprehensive set of 19 pharmaceutical powders having different sizes, surface roughness, morphology, and aspect ratios, as well as assess flow predictability via Bond number estimated using a mechanistic multi-asperity particle contact model.

METHOD

Particle size, shape, density, surface energy and area, SEM-based morphology, and FFC were assessed for all powders. Hydrophobic (R972P) or hydrophilic (A200) nano-silica were dry coated for each powder at 25%, 50%, and 100% surface area coverage (SAC). Flow predictability was assessed via particle size and Bond number.

RESULTS

Nearly maximal flow enhancement, one or more flow category, was observed for all powders at 50% SAC of either type of silica, equivalent to 1 wt% or less for both the hydrophobic R972P or hydrophilic A200, while R972P generally performed slightly better. Silica amount as SAC better helped understand the relative performance. The power-law relation between FFC and Bond number was observed.

CONCLUSION

Significant flow enhancements were achieved at 50% SAC, validating previous models. Most uncoated very cohesive powders improved by two flow categories, attaining easy flow. Flowability could not be predicted for both the uncoated and dry coated powders via particle size alone. Prediction was significantly better using Bond number computed via the mechanistic multi-asperity particle contact model accounting for the particle size, surface energy, roughness, and the amount and type of silica. The widely accepted 200 nm surface roughness was not valid for most pharmaceutical powders.

Current Trends in API Co-Processing: Spherical Crystallization and Co-Precipitation Techniques

Active Pharmaceutical Ingredients (APIs) do not always exhibit processable physical properties, which makes their processing in an industrial setup very demanding. These issues often lead to poor robustness and higher cost of the drug product. The issue can be mitigated by co-processing the APIs using suitable solvent media-based techniques to streamline pharmaceutical manufacturing operations. Some of the co-processing methods are the amalgamation of API purification and granulation steps. These techniques also exhibit adequate robustness for successful adoption by the pharmaceutical industry to manufacture high quality drug products. Spherical crystallization and co-precipitation are solvent media-based co-processing approaches that enhances the micromeritic and dissolution characteristics of problematic APIs. These methods not only improve API characteristics but also enable direct compression into tablets. These methods are economical and time-saving as they have the potential for effectively circumventing the granulation step, which can be a major source of variability in the product. This review highlights the recent advancements pertaining to these techniques to aid researchers in adopting the right co-processing method. Similarly, the possibility of scaling up the production of co-processed APIs by these techniques is discussed. The continuous manufacturability by co-processing is outlined with a short note on Process Analytical Technology (PAT) applicability in monitoring and improving the process.

Functional in situ formed deep eutectic solvents improving mechanical properties of powders by enhancing interfacial interactions

As novel green solvents, deep eutectic solvent (DES) with distinct liquid properties has gained increasing interest in pharmaceutical fields. In this study, DES was firstly utilized for improving powder mechanical properties and tabletability of drugs, and the interfacial interaction mechanism was explored. Honokiol (HON), a natural bioactive compound, was used as model drug, and two novel HON-based DESs were synthesized with choline chloride (ChCl) and l-menthol (Men), respectively. The extensive non-covalent interactions were account for DES formation according to FTIR, ¹H NMR and DFT calculation. PLM, DSC and solid-liquid phase diagram revealed that DES successfully in situ formed in HON powders, and the introduction of trace amount DES (99:1 w/w for HON-ChCl, 98:2 w/w for HON-Men) significantly improve mechanical properties of HON. Surface energy analysis and molecular simulation revealed that the introduced DES promoted the formation of solid-liquid interfaces and generation of polar interactions, which increase interparticulate interactions, thus better tabletability. Compared to nonionic HON-Men DES, ionic HON-ChCl DES exhibited better improvement effect, since their more hydrogen-bonding interactions and higher viscosity promote stronger interfacial interactions and adhesion effect. The current study provides a brand-new green strategy for improving powder mechanical properties and fills in the blank of DES application in pharmaceutical industry.

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.

Experimental Elucidation of Templated Crystallization and Secondary Processing of Peptides

The crystallization of peptides offers a sustainable and inexpensive alternative to the purification process. In this study, diglycine was crystallised in porous silica, showing the porous templates' positive yet discriminating effect. The diglycine induction time was reduced by five-fold and three-fold upon crystallising in the presence of silica with pore sizes of 6 nm and 10 nm, respectively. The diglycine induction time had a direct relationship with the silica pore size. The stable form (α-form) of diglycine was crystallised in the presence of porous silica, with the diglycine crystals obtained associated with the silica particles. Further, we studied the mechanical properties of diglycine tablets for their tabletability, compactability, and compressibility. The mechanical properties of the diglycine tablets were similar to those of pure MCC, even with the presence of diglycine crystals in the tablets. The diffusion studies of the tablets using the dialysis membrane presented an extended release of diglycine through the dialysis membrane, confirming that the peptide crystal can be used for oral formulation. Hence, the crystallization of peptides preserved their mechanical and pharmacological properties. More data on different peptides can help us produce oral formulation peptides faster than usual.

Processability and Oral Bioavailability Improvement of Itraconazole by Particle Engineering Technique

The current study aimed to improve the processability and oral bioavailability of itraconazole (ITZ) via spherical agglomeration. ITZ-spherical agglomerates (ITZ-SA) and ITZ-poloxamer 407-spherical agglomerates (ITZ-PLX-SA) were optimized using Box-Behnken design. Here, the drug release was affected by polymer concentration and stirring speed, whereas particle size was altered by stirring speed, polymer concentration, and amount of bridging liquid. Heckel and Kawakita studies showed a reduction in mean yield pressure and remarkably lowered 1/b value than ITZ, indicating better compactibility and flowability of ITZ-PLX-SA. Physicochemical interactions were not observed during the process, as indicated by ATR-FTIR, DSC, and XRPD. The significant improvement in % drug release of ITZ-PLX-SA was attributed to better wettability and the presence of polymer than ITZ-SA and ITZ. The pharmacokinetic study in rats indicated fivefold enhanced Cmax and twofold improved AUC for ITZ-PLX-SA than plain drug. Thus, spherical agglomeration could improve overall processability and pharmacokinetic profile of ITZ.

Improving the Manufacturability of Cohesive and Poorly Compactable API for Direct Compression of Mini-tablets at High Drug Loading via Particle Engineering

PURPOSE

To utilize a particle engineering strategy to improve the manufacturability of a cohesive and poorly compactable API at high drug loading for direct compression of mini-tablets.

METHODS

A high-shear mixer was used for wet milling during the API manufacturing process to obtain target particle size distributions. The targeted particles were characterized and formulated into blends by mixing with excipients. The formulated blends were compressed directly into mini-tablets using a compaction simulator. The tablet hardness, weight variation, and friability of the mini-tablets were characterized and compared with mini-tablets prepared with hammer milled APIs.

RESULTS

Compared to the hammer milled APIs, the wet milled APIs, had smoother surface, narrower particle size distributions and demonstrated a better flow properties. Moreover, the mini-tablets produced with the wet milled APIs exhibited better weight uniformity, robust tablet mechanical strength and ultimately better friability. In addition, unlike the hammer milled process, the wet milling process is controllable and easy to scale up.

CONCLUSIONS

This study successfully implemented API particle engineering through a high shear wet milling process to produce particles suitable for robust drug product manufacturing.

Surface Modifiers on Composite Particles for Direct Compaction

Direct compaction (DC) is considered to be the most effective method of tablet production. However, only a small number of the active pharmaceutical ingredients (APIs) can be successfully manufactured into tablets using DC since most APIs lack adequate functional properties to meet DC requirements. The use of suitable modifiers and appropriate co-processing technologies can provide a promising approach for the preparation of composite particles with high functional properties. The purpose of this review is to provide an overview and classification of different modifiers and their multiple combinations that may improve API tableting properties or prepare composite excipients with appropriate co-processed technology, as well as discuss the corresponding modification mechanism. Moreover, it provides solutions for selecting appropriate modifiers and co-processing technologies to prepare composite particles with improved properties.

Formulation Development of Fluconazole-Loaded Lactose Agglomerate Tablets as a Disinfectant for Candida-Associated Dentures

Denture stomatitis is induced by irritation or an inflammatory response when wearing a denture for a long time. Candida species are the leading cause of biofilm formation on the surfaces and fissures of dentures. Thus, this study aimed to formulate and evaluate fluconazole tablets for use in preparing a disinfectant mixture with anticandidal activity. For size enlargement of lactose, a tablet diluent, using polyvinylpyrrolidone (PVP) as an agglomerating agent, was developed to enhance the flowability and compactability of the tablet preparation using direct compression. Lactose agglomerates with 6% PVP were used as a diluent for the fluconazole tablets. Furthermore, other excipients were used, such as a buffering agent, disintegrant, surfactant, and lubricant. The fluconazole tablets obtained could be dispersed and dissolved within 10 min in distilled water to achieve a clear mixture, providing a neutral pH and 96% transmittance. Furthermore, the fluconazole mixtures displayed anticandidal efficiency against C. albicans with a similar effect to the standard fluconazole solution. These findings suggest that the fluconazole-loaded lactose agglomerate tablets show strong potential when prepared using direct compression. The fluconazole mixtures made by dispersing the tablets can be used as a disinfectant for Candida-associated dentures, particularly in patients with oral candidiasis.

Downstream Processing of Amorphous and Co-Amorphous Olanzapine Powder Blends

The work evaluates the stability of amorphous and co-amorphous olanzapine (OLZ) in tablets manufactured by direct compression. The flowability and the compressibility of amorphous and co-amorphous OLZ with saccharin (SAC) and the properties of the tablets obtained were measured and compared to those of tablets made with crystalline OLZ. The flowability of the amorphous and mostly of the co-amorphous OLZ powders decreased in comparison with the crystalline OLZ due to the higher cohesiveness of the former materials. The stability of the amorphous and co-amorphous OLZ prior to and after tableting was monitored by XRPD, FTIR, and NIR spectroscopies. Tablets presented long-lasting amorphous OLZ with enhanced water solubility, but the release rate of the drug decreased in comparison with tablets containing crystalline OLZ. In physical mixtures made of crystalline OLZ and SAC, an extent of amorphization of approximately 20% was accomplished through the application of compaction pressures and dwell times of 155 MPa and 5 min, respectively. The work highlighted the stability of amorphous and co-amorphous OLZ during tableting and the positive effect of compaction pressure on the formation of co-amorphous OLZ, providing an expedited amorphization technique, given that the process development-associated hurdles were overcome.

Preparation of Mangosteen Peel Extract Microcapsules by Fluidized Bed Spray-Drying for Tableting: Improving the Solubility and Antioxidant Stability

Mangosteen fruit has been widely consumed and used as a source of antioxidants, either in the form of fresh fruit or processed products. However, mangosteen peel only becomes industrial waste due to its bitter taste, low content solubility, and poor stability. Therefore, this study aimed to design mangosteen peel extract microcapsules (MPEMs) and tablets to overcome the challenges. The fluidized bed spray-drying method was used to develop MPEM, with hydroxypropyl methylcellulose (HPMC) as the core mixture and polyvinyl alcohol (PVA) as the coating agent. The obtained MPEM was spherical with a hollow surface and had a size of 411.2 µm. The flow rate and compressibility of MPEM increased significantly after granulation. A formula containing 5% w/w polyvinyl pyrrolidone K30 (PVP K30) as a binder had the best tablet characteristics, with a hardness of 87.8 ± 1.398 N, friability of 0.94%, and disintegration time of 25.75 ± 0.676 min. Microencapsulation of mangosteen peel extract maintains the stability of its compound (total phenolic and α-mangosteen) and its antioxidant activity (IC50) during the manufacturing process and a month of storage at IVB zone conditions. According to the findings, the microencapsulation is an effective technique for improving the solubility and antioxidant stability of mangosteen peel extract during manufacture and storage.

Particle Agglomeration of Acid-Modified Tapioca Starches: Characterization and Use as Direct Compression Fillers in Tablets

Acid-modified tapioca starches (AMTSs) possessed good compressibility but showed poor particle flowability for preparing tablets by the direct compression method. The aims of this work were to prepare and characterize AMTS agglomerates using polyvinylpyrrolidone (PVP) as an agglomerating agent. The dilution potential and stability studies of the AMTS agglomerates were investigated. The results showed that particle enlargement of TS and AMTS could be achieved via agglomeration using PVP. The thermal behavior and molecular interaction of the agglomerates were revealed using DSC and FTIR spectroscopy, respectively. An increase in PVP concentrations resulted in greater particle strength of the TS agglomerates and a higher acid concentration for modification enhanced the strength of the AMTS agglomerates. All agglomerates presented good particle flowability. Moreover, the AMTS agglomerates provided higher compressibility hardness than the TS agglomerates. The addition of PVP could extend the disintegration time and slow drug dissolution from the agglomerate tablets. The humidity of the storage conditions influenced the thickness and hardness of the AMTS agglomerate tablets, and good physical and chemical stability of the tablets was obtained under ambient conditions and in the refrigerator. Furthermore, the AMTS agglomerates displayed good carrying capacity and possessed desirable characteristics for use in direct compression tablets.

Increasing the Batch Size of a QESD Crystallization by Using a MSMPR Crystallizer

Quasi-emulsion solvent diffusion (QESD) crystallizations can improve the micromeritic properties of drugs and excipients. A solution is dispersed in a miscible antisolvent as a transient emulsion. Using this technique, substances that normally crystallize in the form of e.g., needles, agglomerate into spherical, hollow particles. A disadvantage of QESD crystallizations is that the particle size of the agglomerates decreases with an increased solvent fraction of the mother liquor. Therefore, in batch production, many consecutive runs have to be performed, which is a time- and material-intensive process. The aim of this study was to convert a previously used lab-scale batch crystallizer into a mixed-suspension, mixed-product removal (MSMPR) crystallizer, since the batch size could be simply increased by increasing the run time of the system. The mean residence time (MRT) and solvent fraction in the system was predicted and verified using actual measurement curves. The experiments showed that >50 g QESD metformin hydrochloride could be crystallized in a single run, without observing a large shift in the particle size, while maintaining good flowability. Observations regarding the effect of the MRT on the particle size distribution could be verified for the production on a larger scale than previously described.

Investigation of Quantitative X-ray Microscopy for Assessment of API and Excipient Microstructure Evolution in Solid Dosage Processing

Assessment and understanding of changes in particle size of active pharmaceutical ingredients (API) and excipients as a function of solid dosage form processing is an important but under-investigated area that can impact drug product quality. In this study, X-ray microscopy (XRM) was investigated as a method for determining the in situ particle size distribution of API agglomerates and an excipient at different processing stages in tablet manufacturing. An artificial intelligence (AI)-facilitated XRM image analysis tool was applied for quantitative analysis of thousands of individual particles, both of the API and the major filler component of the formulation, microcrystalline cellulose (MCC). Domain size distributions for API and MCC were generated along with the calculation of the porosity of each respective component. The API domain size distributions correlated with laser diffraction measurements and sieve analysis of the API, formulation blend, and granulation. The XRM analysis demonstrated that attrition of the API agglomerates occurred secondary to the granulation stage. These results were corroborated by particle size distribution and sieve potency data which showed generation of an API fines fraction. Additionally, changes in the XRM-calculated size distribution of MCC particles in subsequent processing steps were rationalized based on the known plastic deformation mechanism of MCC. The XRM data indicated that size distribution of the primary MCC particles, which make up the larger functional MCC agglomerates, is conserved across the stages of processing. The results indicate that XRM can be successfully applied as a direct, non-invasive method to track API and excipient particle properties and microstructure for in-process control samples and in the final solid dosage form. The XRM and AI image analysis methodology provides a data-rich way to interrogate the impact of processing stresses on API and excipients for enhanced process understanding and utilization for Quality by Design (QbD).

Control of Drug-Excipient Particle Attributes with Droplet Microfluidic-based Extractive Solidification Enables Improved Powder Rheology

PURPOSE

Industrial implementation of continuous oral solid dosage form manufacturing has been impeded by the poor powder flow properties of many active pharmaceutical ingredients (APIs). Microfluidic droplet-based particle synthesis is an emerging particle engineering technique that enables the production of neat or composite microparticles with precise control over key attributes that affect powder flowability, such as particle size distribution, particle morphology, composition, and the API's polymorphic form. However, the powder properties of these microparticles have not been well-studied due to the limited mass throughputs of available platforms. In this work, we produce spherical API and API-composite microparticles at high mass throughputs, enabling characterization and comparison of the bulk powder flow properties of these materials and greater understanding of how particle-scale attributes correlate with powder rheology.

METHODS

A multi-channel emulsification device and an extractive droplet-based method are harnessed to synthesize spherical API and API-excipient particles of artemether. As-received API and API crystallized in the absence of droplet confinement are used as control cases. Particle attributes are characterized for each material and correlated with a comprehensive series of powder rheology tests.

RESULTS

The droplet-based processed artemether particles are observed to be more flowable, less cohesive, and less compressible than conventionally synthesized artemether powder. Co-processing the API with polycaprolactone to produce composite microparticles reduces the friction of the powder on stainless steel, a common equipment material.

CONCLUSIONS

Droplet-based extractive solidification is an attractive particle engineering technique for improving powder processing and may aid in the implementation of continuous solid dosage form manufacturing.

Towards a better understanding of the role of stabilizers in QESD crystallizations

Quasi-emulsion solvent-diffusion crystallization (QESD) is a type of spherical crystallization which can be used as a particle design method to improve the flowability and micromeritic properties of drugs or excipients. Spherical particles are generated by dispersing a solvent phase in an antisolvent so that a transient emulsion is formed. Within the droplets the material can crystallize and agglomerate into spherical, hollow particles. Surfactants, such as surface-active polymers like hypromellose, are often required to stabilize the quasi-emulsion. To gain further understanding for the role of the stabilizer, a new screening-method was developed which compared different surface active polymers in solution at similar dynamic viscosities rather than at a set concentration. The dynamic viscosities of a low-viscosity grade hypromellose solution used in the previous publications describing the QESD crystallization of metformin hydrochloride by the authors was used as a target value. QESD crystallizations of metformin hydrochloride (MF) and celecoxib showed that the type of stabilizer and whether it is dissolved in the solvent or antisolvent has an effect on the agglomerates. For MF, the type of hypromellose used can have a significant influence on the properties of the agglomerates. More polymers could be used to stabilize the transient emulsion of celecoxib than previously found in literature. Furthermore, QESD crystallizations seem to be more robust when the stabilizer is dissolved in the antisolvent, however this can lead to a reduced drug load of the agglomerates.

Enabling the direct compression of metformin hydrochloride through QESD crystallization

Metformin hydrochloride is a drug used in the treatment of type 2 diabetes. It shows very poor flowability and agglomeration under storage so that a direct compression of the material into tablets has not yet been successfully realized. In a previous study the authors showed that a quasi-emulsion solvent-diffusion (QESD) crystallization technique can be used to drastically improve the flowability and reduce storage agglomeration of this drug. This study set out to evaluate whether QESD metformin hydrochloride can be directly compressed into high dose (> 89.5% drug load) tablets without the use of an intermediary step such as granulation. The direct compression into tablets was successful, however it was important to evaluate the tabletability of the material under actual production speeds of the tablet press. The porous structure of the metformin agglomerates lead to deaeration issues, however these could be avoided by reducing the punch speed or using a precompression step. Furthermore, the influence of surfactants used to stabilize the QESD crystallization on the strength of tablets produced was analyzed because the literature is still scarce on this topic.

A Co-Processed API Approach for a Shear Sensitive Compound Affording Improved Chemical Stability and Streamlined Drug Product Processing

The physical properties of active pharmaceutical ingredients (API) are critical to both drug substance (DS) isolation and drying operations, as well as streamlined drug product (DP) processing and the quality of final dosage units. High aspect ratio, low bulk density, API 'needles' in particular are a hindrance to efficient processing, with a low probability that conventional crystallization routes can modify the challenging morphology. The compound evaluated in this manuscript demonstrated this non-ideal morphology, with the added complexity of shear sensitivity. Modest shear exposure resulted in conversion of the thermodynamically stable crystalline phase to the amorphous phase, with the amorphous phase then undergoing accelerated chemical degradation. Slow filtration during DS isolation resulted in uncontrolled and elevated amorphous levels, while subsequent DP operations including blending, densification and compression increased amorphous content still further. A chemically stable final dosage unit would ideally involve a high bulk density, free flowing API that did not require densification in order to be commercialized as an oral dosage form with direct encapsulation of a single dosage unit. Despite every effort to modify the crystallization process, the physical properties of the API could not be improved. Here, an innovative isolation strategy using a thin film evaporation (TFE) process in the presence of a water soluble polymer alleviated filtration and drying risks and consistently achieved a high bulk density, free flowing co-processed API amenable to direct encapsulation. Characterization of the engineered materials suggested the lower amorphous levels and reduced shear sensitivity were achieved by coating surfaces of the API at relatively low polymer loads. This particle engineering route blurred conventional DS/DP boundaries that not only achieved improved chemical stability but also resulted in a optimized material, with simplified and more robust processing operations for both drug substance and drug product.

Direct compression tablet formulation of celecoxib enabled with a pharmaceutical solvate

Celecoxib, an anti-inflammatory drug for pain and arthritis, is currently only available in capsule form. To reduce the onset time for a faster action and to lower the manufacturing cost, the tablet dosage form is more preferred. However, the commercial celecoxib (Form III) is not suitable for direct compression (DC) tablet manufacture due to poor flow, low bulk density, and tablet lamination. In this work, we overcome these challenges using a pharmaceutically acceptable dimethyl sulfoxide (DMSO) solvate of celecoxib. Aided with the DMSO solvate, an acceptable DC tablet formulation was successfully developed to manufacture tablets containing 200 mg celecoxib, with satisfactory manufacturability, disintegration, and in vitro dissolution performance.

Pharmaceutical nanoparticle isolation using CO2-assisted dynamic bed coating

Poor solubility of new chemical entities (NCEs) is a major bottleneck in the pharmaceutical industry which typically leads to poor drug bioavailability and efficacy. Nanotechnologies offer an interesting route to improve the apparent solubility and dissolution rate of pharmaceutical drugs, and processes such as nano-spray drying and supercritical CO₂-assisted spray drying (SASD) provide a route to engineer and produce solid drug nanoparticles. However, dried nanoparticles often show poor rheological properties (e.g. flowability, tabletability) and their isolation using these methods is typically inefficient and leads to poor collection yields. The work presented herein demonstrates a novel production and isolation method for drug nanoparticles using a 'top spray dynamic bed coating' process, which uses CO₂ spray as the fluidizing gas. Nanoparticles of three BCS class II Active Pharmaceutical Ingredients (APIs), namely carbamazepine (CBZ), ketoprofen (KET) and risperidone (RIS), were produced and successfully coated onto micron-sized microcrystalline cellulose (MCC) particles. The size distribution of the API nanoparticles was in the range of 90-490 nm. The stable forms of CBZ (form III), KET (form I), and the metastable form of RIS (form B) were produced and coated onto MCC carrier microparticles. All the isolated solids presented optimal rheological properties along with a 2-6 fold improvement in the dissolution rate of the corresponding APIs. Hence, the 'top spray dynamic bed coater' developed in this work demonstrates to be an efficient approach to produce and coat API nanoparticles onto carrier particles with optimal rheological properties and improved dissolution.

A Bilayer Vaginal Tablet for the Localized Delivery of Disulfiram and 5-Fluorouracil to the Cervix

This study was performed to develop an adjuvant therapy in the form of a self-administered vaginal tablet regimen for the localized delivery of chemotherapeutic drugs. This therapy will help to reduce relapse by eradicating cancerous cells in the margin of cervical tumors. The vaginal tablet is a very common formulation that is easy to manufacture, easy to place in the vagina, and has a low cost of manufacture, making them ideal for use in developing countries. A combination of disulfiram and 5-fluorouracil, which are both off-patent drugs and provide different modes of action, were evaluated. The tablets developed were evaluated for weight variation, thickness, hardness, friability, swelling index, differential scanning calorimetry (DSC), particle morphology, in vitro drug release, and cytotoxicity on Ca-Ski cells. Both layers were designed to release both drugs concurrently for a synergistic effect. The polymer–polymer interaction between the layers was able to reduce the loss of formulation due to chitosan. While the bilayer tablet had satisfactory performance in the physicochemical tests, in vitro cell culture with Ca-Ski also showed a synergistic effect using a combination of drugs at a low dose. However, the formulation only had 24-h dose release before degradation. Further drug combinations should be evaluated in subsequent studies.

Development of piroxicam mini-tablets enabled by spherical cocrystallization

We examined the potential of the spherical cocrystallization (SCC) technology in simultaneously enhancing tablet manufacturability and dissolution of poorly soluble drugs by developing a mini-tablet formulation of piroxicam. The manufacturing of mini-tablets using a direct compression (DC) process is more challenging than conventional tablets because of the much stricter requirement on the micromeritic properties of formulated powders. The SCC process in this work involved two steps: 1) preparing a new piroxicam-ferulic acid (PRX-FA) cocrystal, and 2) forming spherical agglomerates with the aid of a suitable bridging liquid. The PRX-FA cocrystal exhibited enhanced solubility as well as improved plasticity. The bridging liquid, a mixture of chloroform and ethyl acetate (EA) (1: 2, v/v), was chosen based on the high computed adsorption energy of chloroform and EA on morphologically dominating crystal faces of PRX-FA. The improved flowability, tabletability, and dissolution rate of spherical PRX-FA enabled the successful development of a DC mini-tablet formulation with a high PRX loading (41 wt%). This example shows that SCC is a powerful enabling technology for DC tablet formulation development of challenging drugs.

Evaluation of an external lubrication system implemented in a compaction simulator

The internal blending of magnesium stearate is often associated with decreasing tensile strengths and longer disintegration and dissolution times. Therefore, external lubrication has gained interest in the pharmaceutical industry as these negative effects could be minimized using this method. In this study, an external lubrication system implemented in a compaction simulator was investigated. The influence of 2 process parameters related to the external lubrication system, spraying time and atomizing pressure, on the responses was studied using 4 common fillers and 2 model drugs. While the parameters of the external lubrication system had a significant impact on the ejection forces, no negative effect was observed on the tensile strength and disintegration time as similar values were obtained compared to non-lubricated experiments. Moreover, equal or lower ejection forces were obtained for external lubrication using a lower concentration of magnesium stearate compared to internal lubrication, where a decrease in tensile strength and prolonged disintegration was noticed for most formulations. The observed results could be correlated to the wall friction angle, compaction properties and tablet brittleness index of the raw materials and blends. This study showed the potential of external lubrication as an alternative lubrication method for lubricant-sensitive formulations.

Embedded droplet printing in yield-stress fluids

Microfluidic tools and techniques for manipulating fluid droplets have become core to many scientific and technological fields. Despite the plethora of existing approaches to fluidic manipulation, non-Newtonian fluid phenomena are rarely taken advantage of. Here we introduce embedded droplet printing-a system and methods for the generation, trapping, and processing of fluid droplets within yield-stress fluids, materials that exhibit extreme shear thinning. This technique allows for the manipulation of droplets under conditions that are simply unattainable with conventional microfluidic methods, namely the elimination of exterior influences including convection and solid boundaries. Because of this, we believe embedded droplet printing approaches an ideal for the experimentation, processing, or observation of many samples in an "absolutely quiescent" state, while also removing some troublesome aspects of microfluidics including the use of surfactants and the complexity of device manufacturing. We characterize a model material system to understand the process of droplet generation inside yield-stress fluids and develop a nascent set of archetypal operations that can be performed with embedded droplet printing. With these principles and tools, we demonstrate the benefits and versatility of our method, applying it toward the diverse applications of pharmaceutical crystallization, microbatch chemical reactions, and biological assays.

Improved processability of ethambutol hydrochloride by spherical agglomeration

Ethambutol hydrochloride (ETB), high dose anti-tubercular drug exhibits poor micromeritics and compressibility. The current study aimed to enhance flow, compressibility and packing characteristics, thereby improving processability of ETB by spherical agglomeration. Quasi emulsion solvent diffusion method was used for agglomeration process in which saturated aqueous ETB solution was prepared and the crystallization was carried out subsequently at different ratios of acetone and ethyl acetate which act as anti-solvent. Further the process was optimised statistically using 3² factorial design keeping 'speed of stirring' and 'ratio acetone and ethyl acetate' as independent variables and particle size as dependent variable. Optimised batch of ethambutol hydrochloride spherical agglomerates (ETB-SA) was characterised for sieve analysis, solid state characteristics and Kawakita analysis. The uniformity of ETB-SA was observed with SEM while XRPD studies revealed reduction in crystallinity for ETB-SA. DSC and FTIR indicated no polymeric or chemical alteration during crystallization process. The flow properties of ETB-SA were found superior and its Kawakita parameters indicated improved packability and flowability compared to ETB. ETB has high solubility in water therefore was no significant difference was observed in in vitro dissolution of ETB and ETB-SA. Thus spherical agglomeration, a revered particle engineering technique, continues to be a salient approach for enhancing processability of high-dose drugs like ETB.