Effects of interactions between powder particle size and binder viscosity on agglomerate growth mechanisms in a high shear mixer

High-Shear Wet Granulation of SMEDDS Based on Mesoporous Carriers for Improved Carvedilol Solubility

Mesoporous carriers are a convenient choice for the solidification of self-microemulsifying drug delivery systems (SMEDDS) designed to improve the solubility of poorly water-soluble drugs. They are known for high liquid load capacity and the ability to maintain characteristics of dry, free-flowing powders. Therefore, five different mesoporous carriers were used for the preparation of carvedilol-loaded SMEDDS granules by wet granulation methods—in paten (manually) and using a high-shear (HS) granulator. Granules with the highest SMEDDS content (63% and 66% of total granules mass, respectively) and suitable flow properties were obtained by Syloid^® 244FP and Neusilin^® US2. SMEDDS loaded granules produced by HS granulation showed superior flow characteristics compared to those obtained manually. All SMEDDS granules exhibited fast in vitro release, with 93% of carvedilol releasing from Syloid^® 244FP-based granules in 5 min. Upon compaction into self-microemulsifying tablets, suitable tablet hardness and very fast disintegration time were achieved, thus producing orodispersible tablets. The compaction slightly slowed down the carvedilol release rate; nevertheless, upon 1 h (at pH 1.2) or 4 h (at pH 6.8) of in vitro dissolution testing, the amount of released drug was comparable with granules, confirming the suitability of orodispersible tablets for the production of the SMEDDS loaded single unit oral dosage form.

Preparation of Polystyrene Microsphere-Templated Porous Monolith for Wastewater Filtration

Porous monoliths prepared using templates are highly sought after for filtration applications due to their good mass transport properties and high permeability. Current templates, however, often lead to the formation of dead-end pores and irregular pore distributions, which reduce the efficiency of the substrate flow across the monolith column. This study focused on the preparation of a microsphere-templated porous monolith for wastewater filtration. The optimal template/monomer ratio (50:50, 60:40, 70:30) was determined, and appropriate template removal techniques were assessed for the formation of homogenous pores. The physicochemical characteristics and pore homogeneity of the monoliths were examined. The 60:40 ratio was determined to result in monoliths with homogeneous pore distributions ranging from 1.9 μm to 2.3 μm. SEM and FTIR investigations revealed that solvent treatment was effective for removing templates from the resulting solid monolith. The water quality assessments revealed reductions in the turbidity and the total number of suspended particles in the tested wastewater of up to 96–99%. The findings of this study provide insightful knowledge regarding the fabrication of monoliths with homogenous pores that are beneficial for wastewater treatment.

Synthesis and Characterization of Polymeric Microspheres Template for a Homogeneous and Porous Monolith

Monolith is an emerging technology applicable for separation, filtration, and chromatography due to its interconnected pore structure. However, the current templates used to form monolith pores are associated with poor heat dissipation, uneven pore size distribution, and relatively low mechanical strength during monolith scale-up. Templates made from polymeric microsphere particles were synthesized via a solvent evaporation technique using different types of polymer (polystyrene, polycaprolactone, polypropylene, polyethylene, and poly (vinyl-alcohol) at varied polymer (10-40 wt%) and surfactant (5-10%) concentrations. The resulting microsphere particles were tested as a monolith template for the formation of homogenous pores. Among the tested polymers, polystyrene at 10 wt% concentration demonstrated good particle morphology determined to around 1.94-3.45 µm. The addition of surfactant at a concentration of 7-10 wt% during microsphere synthesis resulted in the formation of well-shaped and non-aggregating microsphere particles. In addition, the template has contributed to the production of porous monoliths with enhanced thermal stability. The thermogravimetric analysis (TGA) indicated monolith degradation between 230 °C and 450 °C, implying the material excellent mechanical strength. The findings of the study provide insightful knowledge on the feasibility of polymeric microsphere particles as a pore-directing template to fabricate monoliths with desired pore structures.

Effect of Various Types of Sugar Binder on the Physical Properties of Gum Powders Prepared via Fluidized-Bed Agglomeration

Particle agglomeration of fine gum powders to improve their physical and morphological characteristics is of crucial importance. Changes in the physical properties of guar gum, locust bean gum, and carboxymethyl cellulose powders subjected to fluidized-bed agglomeration with various sugar types as the binder were examined. The agglomerates with sugar binders had much larger particles (D₅₀) and higher porosity (ε) than the corresponding fine gum powders, as confirmed by particle-size-distribution analysis and scanning electron microscopy. In particular, the carboxymethyl cellulose agglomerate exhibited much higher D₅₀ and ε values than the original fine gum powder, with sorbitol as the binder resulting in the highest D₅₀ and ε values. Except for guar gum with sorbitol as the binder, the guar gum and locust bean gum agglomerates with the other sugar binders showed lower Carr index and Hausner ratio values (thus exhibiting better flowability and lower cohesiveness) than the original powders, whereas those of the carboxymethyl cellulose agglomerates were higher. These findings indicate that the physical and structural properties of gum powders can be greatly improved according to the type of gum and sugar solution used in the agglomeration process.

Effect of Biodegradable Binder Properties and Operating Conditions on Growth of Urea Particles in a Fluidized Bed Granulator

Granulation is an important step during the production of urea granules. Most of the commercial binders used for granulation are toxic and non-biodegradable. In this study, a fully biodegradable and cost-effective starch-based binder is used for urea granulation in a fluidized bed granulator. The effect of binder properties such as viscosity, surface tension, contact angle, penetration time, and liquid bridge bonding force on granulation performance is studied. In addition, the effect of fluidized bed process parameters such as fluidizing air inlet velocity, air temperature, weight of primary urea particles, binder spray rate, and binder concentration is also evaluated using response surface methodology. Based on the results, binder with higher concentration demonstrates higher viscosity and higher penetration time that potentially enhance the granulation performance. The viscous Stokes number for binder with higher concentration is lower than critical Stokes number that increases coalescence rate. Higher viscosity and lower restitution coefficient of urea particles result in elastic losses and subsequent successful coalescence. Statistical analysis indicate that air velocity, air temperature, and weight of primary urea particles have major effects on granulation performance. Higher air velocity increases probability of collision, whereby lower temperature prevents binder to be dried up prior to collision. Findings of this study can be useful for process scale-up and industrial application.

A novel insight into fluid bed melt granulation: Temperature mapping for the determination of granule formation with the in-situ and spray-on techniques

The in-line control of pharmaceutical processes has become a necessary tool for the evaluation and follow-up of pharmaceutical dosage forms. In this study, a novel approach to the evaluation of conditions established in a conical fluid bed granulator during the in-situ and spray-on fluid bed melt granulation (FBMG) techniques was developed. The determination of temperature mappings allowed the characterization of the critical zones during the melt granulation and the prediction of the volume of the wetting zone, hence enabling the identification of the areas of optimal granule growth. Two grades of polyethylene glycol (PEG 2000 and 6000) were used as meltable binders in three binder spraying rates and droplet size fractions for spray-on and three binder particle sizes and contents for in-situ. The results showed the presence of intense heat exchange in the bottom of the bed during the in-situ technique and under the spraying nozzle during the spray-on technique, identified as the wetting zone. Isotherm maps enabled the identification of the transition between the wetting, cooling and consolidation zones for the spray-on and the cooling zone for the in-situ technique. The shape and volume of the wetting zone was highly dependent on binder spraying rate and spraying pressure for spray-on and binder particle size and content for in-situ FBMG. Granule size and size distribution were correlated to the volume of the wetting zone and an optimized wetting volume interval was determined for both spray-on and in-situ techniques for the optimal quality attributes of the granules.

Investigate the effect of solvents on wet granulation of microcrystalline cellulose using hydroxypropyl methylcellulose as a binder and evaluation of rheological and thermal characteristics of granules

Wet granulation is the most commonly used technique in the pharmaceutical industry for delivering oral solid dosage forms. In wet granulation, the binder solvent is one of the critical factors affecting granule properties. In the current study, an attempt was made to investigate the effect of solvents (aqueous and hydro-alcoholic) on thermal and flow properties of Microcrystalline Cellulose (MCC) granules prepared using two different grades of Hydroxypropyl Methylcellulose (HPMC), which served as an effective binder. The granulation endpoint was evaluated using thermal effusivity sensor. Rheometer and Modulated Differential Scanning Calorimetry (mDSC) was used to study the flow and thermal properties of wet and dried granules. Furthermore, physical characterization was carried out by granule strength, particle size distribution and tablet hardness for all granules under the study. Thermal effusivity sensor results indicate 55% w/w concentration of binder solution as the endpoint by measuring thermal effusivity for both binders. Additionally, powder rheometer results show that the wet granules of hydro-alcoholic batches show greater resistance to flow whereas the dried granules display excellent flow characteristics as evident from Basic flowability energy values and specific energy values. Permeability results suggest that the granules formed with hydro-alcoholic binder solvent exhibit better porosity and permeability. Tablet hardness data showed that tablets formulated using hydro-alcoholic solvent granules have greater hardness than tablets formulated using water based solvent granules. The granule strength for water based granules is relatively higher than that of hydro-alcoholic based granules. mDSC thermograms show a sharp rise in enthalpy value at 55% w/w binder solution which is indicative of a more significant amount of solvent being present on the surface of granules and formation of optimal granules. To summarize, we have determined a technique to measure endpoint determination and simultaneously investigate the role of solvent systems on the rheology of MCC granules, which could assist in selecting an appropriate solvent system for granulation.

Impact of non-binder ingredients and molecular weight of polymer binders on heat assisted twin screw dry granulation

Two grades of commercial AFFINISOL™ HPMC HME were used as polymer binders to explore the influence of polymer viscosity and concentration on a novel heat assisted dry granulation process with a twin screw extruder. Contributions of other non-binder ingredients in the formulations were also studied for lactose, microcrystalline cellulose and an active pharmaceutical ingredient of caffeine. As sensitive indicators of processing conditions that expose the drug to high internally generated heat, dehydration of α-lactose monohydrate and polymorphic transformation of caffeine were monitored by differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD). Additionally, any decomposition of caffeine was determined by high-performance liquid chromatography (HPLC). Granular samples were characterized by particle size, circularity, fracture strength and their temperature on the exit of extruder. Higher screw speed and lower feed rate were found to help particles agglomerate by allowing feed particles a greater opportunity to increase in temperature. Lower binder molecular weight and higher binder concentration enable granules to build stronger strength and thereby lead to higher particle size. This new twin screw dry granulation was demonstrated as offering advantages over conventional hot melt granulation by minimizing thermal degradation of the tested ingredients.

The use of Rheology Combined with Differential Scanning Calorimetry to Elucidate the Granulation Mechanism of an Immiscible Formulation During Continuous Twin-Screw Melt Granulation

PURPOSE

Twin screw hot melt granulation (TS HMG) is a valuable, but still unexplored alternative to continuous granulation of moisture sensitive drugs. However, knowledge of the material behavior during TS HMG is crucial to optimize the formulation, process and resulting granule properties. The aim of this study was to evaluate the agglomeration mechanism during TS HMG using a rheometer in combination with differential scanning calorimetry (DSC).

METHODS

An immiscible drug-binder formulation (caffeine-Soluplus(®)) was granulated via TS HMG in combination with thermal and rheological analysis (conventional and Rheoscope), granule characterization and Near Infrared chemical imaging (NIR-CI).

RESULTS

A thin binder layer with restricted mobility was formed on the surface of the drug particles during granulation and is covered by a second layer with improved mobility when the Soluplus(®) concentration exceeded 15% (w/w). The formation of this second layer was facilitated at elevated granulation temperatures and resulted in smaller and more spherical granules.

CONCLUSION

The combination of thermal and rheological analysis and NIR-CI images was advantageous to develop in-depth understanding of the agglomeration mechanism during continuous TS HMG and provided insight in the granule properties as function of process temperature and binder concentration.

Vibrational spectroscopy to support the link between rheology and continuous twin-screw melt granulation on molecular level: A case study

Twin screw hot melt granulation (TSHMG) is an innovative and continuous drug formulation process allowing granulation of moisture sensitive drugs. However, due to the lack of experience and in-depth process understanding, this technique is not yet widely used. During the TSHMG process, the microstructure of the granules is generated and modified and strongly depends on the flow behavior of the material. Hence, rheology might be a suitable tool to simulate and examine this process. However, chemical interactions of the material are influencing the physical properties leading to the microstructure. In this research project it is spectroscopically investigated whether the heat applied in a rheometer induces the same molecular effects as these occurring during TSHMG of the model formulation caffeine anhydrous/Soluplus®. Hence, it is evaluated whether rheology can be used as a simulation tool to improve the understanding of the material behavior at molecular level during continuous melt granulation. Therefore, in-line Raman spectroscopy is executed during TSHMG and in situ Fourier Transform Infra-red (FTIR) during oscillatory rheological experiments. The results from the in-line Raman monitoring revealed polymorph transition of caffeine anhydrous during twin screw melt granulation with Soluplus® which is stimulated depending on the binder concentration and/or granulation temperature. A correlation was seen between the FTIR spectra obtained during the rheological temperature ramp and the in-line collected Raman spectra during the melt granulation runs. The polymorphic conversion of caffeine anhydrous could be detected in the same temperature range with both techniques, proving the comparability of plate-plate rheometry and hot melt granulation (HMG) for this case with the used parameter settings. Process simulation using rheology combined with in situ FTIR seems a promising approach to increase process understanding and to facilitate binder and parameter selection for TSHMG.

Preparation and characterization of curcumin-piperine dual drug loaded nanoparticles

OBJECTIVE

To prepare curcumin-piperine (Cu-Pi) nanoparticles by various methods and to study the effect of various manufacturing parameters on Cu-Pi nanoparticles and to identify a suitable method for the preparation of Cu-Pi nanoparticles to overcome oral bioavailability and cancer cell targeting limitations in the treatment of cancer.

METHODS

Cu-Pi nanoparticles were prepared by thin film hydration method, solid dispersion method, emulsion polymerization method and Fessi method. Optimization was carried out to study the effect of various manufacturing parameter on the Cu-Pi nanoparticles.

RESULTS

Out of four methods, Fessi method produced a minimum average particle size of 85.43 nm with a polydispersity index of 0.183 and zeta potential of 29.7 mV. Change of organic solvent (acetone or ethanol) did not have any significant effect on Cu-Pi nanoparticles. However, increase in sonication time, stirring speed, viscosity, use of 1:10:10 ratio of drug/polymer/surfactant, and use of anionic surfactant or combination of anionic surfactant with cationic polymer or combination of non-ionic surfactant with cationic polymer had a significant effect on Cu-Pi nanoparticles.

CONCLUSIONS

Cu-Pi nanoparticles coated with PEG containing copolymer produced by Fessi method had a minimum average particle size, excellent polydispersity index and optimal zeta potential which fall within the acceptable limits of the study. This dual nanoparticulate drug delivery system appears to be promising to overcome oral bioavailability and cancer cell targeting limitations in the treatment of cancer.

Spherical Granule Production from Micronized Saltwort (Salicornia herbacea) Powder as Salt Substitute

The whole saltwort plant (Salicornia herbacea) was micronized to develop the table salt substitute. The micronized powder was mixed with distilled water and made into a spherical granule by using the fluid-bed coater (SGMPDW). The SGMPDW had superior flowability to powder; however, it had low dispersibility. To increase the dispersibility of SGMPDW, the micronized powder was mixed with the solution, which contained various soluble solid contents of saltwort aqueous extract (SAE), and made into a spherical granule (SGMPSAE). The SGMPSAE prepared with the higher percentages of solid content of SAE showed improved dispersibility in water and an increase in salty taste. The SGMPSAE prepared with 10% SAE was shown to possess the best physicochemical properties and its relative saltiness compared to NaCl (0.39). In conclusion, SGMPSAEs can be used as a table salt substitute and a functional food material with enhanced absorptivity and convenience.

Drug distribution in wet granulation: foam versus spray

Foam granulation technology is a new wet granulation approach for pharmaceutical formulations. This study evaluates the performance of foam and spray granulation in achieving uniform drug distribution using a model formulation. To observe wetting and nuclei formation, single drop/foam penetration experiments were performed on a static powder bed comprised of varying compositions of hydrophilic/hydrophobic glass ballotini, and hydrophilic lactose/hydrophobic salicylic acid respectively. High shear granulation experiments were performed in a 5L mixer using varying compositions of hydrophilic lactose and hydrophobic salicylic acid. Four percent hydroxylpropyl methylcellulose (HPMC) solution was delivered at 90 g/min as either a foam (92% FQ) or an atomized spray whilst recording impeller power consumption. After drying, the granule size distribution was measured and the granule composition was estimated using gravimetric filtration in methanol. Foam penetration was less dependent on the powder hydrophobicity compared to drop penetration. For glass ballotini powder mixtures, foam induced nucleation created nuclei with relatively uniform structure and size regardless of the powder hydrophobicity. For salicylic acid and lactose mixtures, increasing the proportion of salicylic acid reduced the nuclei granule size for both foam and drop binder addition. The granule drug distribution was not significantly affected by the binder addition method. Processing conditions, including liquid binder amount, impeller speed, wet massing, and the wettability properties of the formulation were the dominant factors for delivering homogeneous granules. The study reveals that foam and spray granulation involve different nucleation mechanisms - spray tends to incur early liquid penetration whereas foam granulation operates well in mechanical dispersion.

A combined experimental and modeling approach to study the effects of high-shear wet granulation process parameters on granule characteristics

The purpose of the current work is to study the effects of high-shear wet granulation process parameters on granule characteristics using both experimental and modeling techniques. A full factorial design of experiments was conducted on three process parameters: water amount, impeller speed and wet massing time. Statistical analysis showed that the water amount has the largest impact on the granule characteristics, and that the effect of other process variables was more pronounced at higher water amount. At high water amounts, an increase in impeller speed and/or wet massing time showed a decrease in granule porosity and compactability. A strong correlation between granule porosity and compactability was observed. A three-dimensional population balance model which considers agglomeration and consolidation was employed to model the granulation process. The model was calibrated using the particle size distribution from an experimental batch to ensure a good match between the simulated and experimental particle size distribution. The particle size distribution of three other batches were predicted, each of which was manufactured under different process parameters (water amount, impeller speed and wet massing time). The model was able to capture and predict successfully the shifts in granule particle size distribution with changes in these process parameters.

The influence of thermal history on the physical behavior of poly(ethylene glycol) (PEG)

OBJECTIVES

To investigate the influence of thermal history on the physical behavior of poly(ethylene glycol) (PEG), commonly used as a pharmaceutical excipient.

MATERIALS AND METHODS

Rheological investigations together with SEM imaging and solid state analysis by XRPD and DSC were used to characterize PEG as starting material, as well as PEG:lactose monohydrate granules. For granulation experiments PEG 6000 was used and for further investigations of physicochemical properties, three M(w) of PEG (3000-10000) with different thermal histories obtained by melting the PEG followed by solidification with specific cooling rates.

RESULTS AND DISCUSSION

More uniform granules were obtained when fast cooled PEG was used as binder. XRPD suggested similar crystallinity for the different M(w) and thermal history did not influence the results drastically. However, rheological analysis and DSC measurements indicated different melting behavior dependent on the M(w) of PEG. PEG 6000 and 10000 were affected by the thermal treatment where stepwise melting was observed with slower cooling rate probably due to increased formation of extended structures.

CONCLUSIONS

Increased cooling rate gives rise to increased randomness, more folded structure of PEG, which reflects in the outcome of the granulation process.