Mini Spray Dryer Research Articles

Isothermal Microcalorimetry To Investigate the Phase Separation for Amorphous Solid Dispersions of AMG 517 with HPMC-AS

Understanding the crystallization kinetics of an amorphous drug is critical for the development of an amorphous solid dispersion (ASD) formulation. This paper examines the phase separation and crystallization of the drug AMG 517 in ASDs of varying drug load at various conditions of temperature and relative humidity using isothermal microcalorimetry. ASDs of AMG 517 in hydroxypropyl methylcellulose acetate succinate (HPMC-AS) were manufactured using a Buchi 290 mini spray dryer system. ASDs were characterized using modulated differential scanning calorimetry (mDSC) and scanning electron microscopy (SEM) prior to isothermal microcalorimetry evaluation, and crystallinity was measured using (19)F solid state nuclear magnetic resonance spectroscopy (SSNMR), before and after crystallization. The crystallization of ASDs of AMG 517 in HPMC-AS was significantly slowed by the presence of HPMC-AS polymer, indicating enhanced physical stability for the ASD formulations. A two-phase crystallization was observed by isothermal microcalorimetry at temperatures near the glass transition temperature (Tg), indicating a drug-rich phase and a miscible ASD phase. (19)F SSNMR showed that only partial crystallization of the drug occurred for the ASDs, suggesting a third phase which did not crystallize, possibly representing a thermodynamically stable, soluble component. Isothermal microcalorimetry provides important kinetic data for monitoring crystallization of the drug in the ASDs and, together with (19)F SSNMR, suggests a three-phase ASD system for AMG 517 in HPMC-AS.

Capreomycin supergenerics for pulmonary tuberculosis treatment: Preparation, in vitro, and in vivo characterization

The pulmonary route is one of the main strategies investigated to improve tuberculosis therapy. The aim of this study was to develop a simple and scalable method to produce capreomycin inhalable powders to use as supergeneric. In vitro antimycobacterial activity and in vivo acute toxicity were assessed using agar proportion susceptibility test on Mycobacterium tuberculosis and chicken chorioallantoic membrane assay, respectively. Capreomycin and three different hydrophobic counterions, namely oleate, linoleate, and linolenate, were combined in solution to obtain hydrophobic ion-pairs that were successively spray-dried. Ion-pairing efficiency was influenced by the spray-dryer employed to produce the powder. In the case of capreomycin oleate, both instruments, mini and nano spray-dryer, were suitable to maintain a high ion-paired content, while for capreomycin linoleate and linolenate, mini spray-dryer was the most appropriate instrument. The three formulations showed morphology and particle sizes potentially suitable for inhalation. Capreomycin oleate and linoleate showed the same efficacy of capreomycin sulfate against M. tuberculosis, while capreomycin linolenate showed a reduced efficacy, even though strain growth was inhibited at 10−4 mycobacterial inoculum. In vivo acute toxicity studies evidenced the lowest toxic potential for capreomycin oleate when compared to the single components or the other two salts. Overall, capreomycin oleate seems to possess the most promising characteristics to be used as supergenerics in pulmonary tuberculosis treatment.

The correlation of wall material composition with flow characteristics and encapsulation behavior of fish oil emulsion

The objective of this study was to examine the effect of wall material composition and the presence of tween 20 in emulsion formula on fish oil microcapsule properties produced by spray drying. A total of 4 wall materials including skim milk powder (SMP), 70% SMP+30% maltodextrin, 70% SMP+30% lactose, 70% SMP+30% sucrose, and all of these wall materials with 1g tween/100g fish oil were used for emulsion preparation. The prepared emulsions were characterized with respect to droplet size, surface tension, viscosity, and viscoelastic properties. The emulsions were dried in mini-spray dryer at drying air temperature of 175°C. Results showed that tween significantly influenced the properties of emulsion and slightly but not statistically significant increased the encapsulation efficiency. The microcapsules produced by 70% SMP+30% lactose and 70% SMP+30% sucrose were selected as the best microcapsules according to high encapsulation efficiency and acceptable level of peroxide value. Differential scanning calorimetry (DSC) and Fourier‐transformed infrared (FT‐IR) analyses of these microcapsules revealed no chemical interaction between fish oil and wall material in the structure of capsules.

Optimization of emulsification procedure for mutual maximizing the encapsulation and exergy efficiencies of fish oil microencapsulation

The aim of this work was to study the influence of emulsion characteristics on exergy efficiency and quality of fish oil microencapsulated within skim milk powder (SMP) by spray drying. Response surface method (RSM) and genetic algorithm (GA) were applied to optimize the emulsion preparation procedure for production of fish oil microcapsule. The proposed emulsions were prepared, according to a central composite design and the feeds were dried using a mini spray dryer. Independent variables were: aqueous phase content, oil proportion in total solids, and emulsification time. The encapsulation efficiency and exergy efficiency were considered as dependent variables. The RSM was used to build the mathematical equations and created models were integrated by applying three approaches to determine the fitness value of GA. Finally, the optimal emulsion preparation procedure was determined to simultaneously obtain the highest values for both encapsulation efficiency and exergy efficiency. The results of authentication test for selected emulsion procedure preparation demonstrated the ability of applied approach for designation of sustainable and qualified process in fish oil microencapsulation by spray drying.

Influence of Diluents on Physical Properties of Soybean Extracted Powder Prepared by Spray Drying Method

soflavones, a special phenolic group found in soybean, have been found to act as antioxidant and are widely used in pharmaceutics and nutraceuticals. Due to the storage and handling problem, the extract has been prepared in dry form by spray drying technique. The condition of extract solution prior to spray drying has been reported to affect the property of dried powder. The aim of this work was to evaluate the effect of diluents on the physical properties of soybean extracted powder. The experiment was carried out by a Büchi B-290 Mini Spray Dryer. Four types of diluents were applied, they weremannitol, maltrodextrin, and 2 types of modified starch The comparison was then made among those with diluents and without diluent as a carrier. The physicochemical property was then characterized for flowability, moisture content, morphology, particle size and X-ray diffraction. From the results, the addition of all diluents could improve the physicochemical properties of soybean extracted powder indicating the improvement in morphology and hence the better flow property .The types of diluent also had the effect on the extracted powder. Maltodextrin and modified starch exhibited the best carrier in term of improvement of flow property. Therefore, the spray drying technique was successfully used to prepare microparticles of soybean extracted powder and by taking into consideration of the selection of suitable diluents, the good quality of soybean extracted powder could be achieved.

Influence of spray dryer parameters on exergetic performance of microencapsulation processs

Exergy analysis of fish oil microencapsulation process by spray drying was carried out. The process was performed on a mini–spray dryer and skim milk powder was used as the coating wall material. The drying experiments were conducted to find the effects of inlet drying air temperature, drying air mass flow rate, feed mass flow rate, and spraying gas mass flow rate on inlet exergy, outlet exergy, exergy destruction, exergy loss, entropy generation, exergy efficiency, and improvement potential. Results indicated that the magnitude of parameters studied depend on the operational conditions of dryer.

Energy and exergy analyses of the spray drying process of fish oil microencapsulation

An energy and exergy analysis was carried out on the process of fish oil microencapsulation using spray drying. The process was carried out on a mini-spray dryer conducted at three drying air temperatures of 140, 160, and 180 °C. Various milk-originated single, and composite wall materials including skim milk powder (SMP), whey protein concentrate (WPC), whey protein isolate (WPI), 80% WPI + 20% milk protein concentrate (MPC), and 80% WPI + 20% sodium caseinate (NaCas) were used in the formulation of emulsions. The effects of drying air temperature and wall material on the energy efficiency, energy loss from drying chamber, exergy efficiency, exergy destruction, entropy generation and improvement potential were investigated. The energy and exergy efficiency values for spray drying process of fish oil microencapsulation at the drying air temperature between 140 and 180 °C were found to be in the ranges of 7.48–8.54% and 5.25–7.42%, respectively. The results of this study also confirmed that the exergy analysis using second law of thermodynamics is a potential tool for optimising dryer operation and design.

Encapsulation of a pressure-sensitive adhesive by spray-drying: microparticles preparation and evaluation of their crushing strength

An industrial pressure-sensitive adhesive was microencapsulated by spray-drying using an aqueous colloidal ethylcellulose dispersion (Aquacoat® ECD) plasticised by triacetin to form the wall material. Unloaded (0:100) and adhesive-loaded (25:75) particles were produced in a Büchi B-191 mini spray-dryer with product yields of 62% and 57%, respectively. Microparticles were spherical and narrow sized with mean D3,2 diameters of 3.165 ± 0.001 and 5.544 ± 0.105 µm, respectively. The microparticles were found to redisperse well in water and exhibit enough stability in neutral and alkaline aqueous media to be further used in a coating slip. Crush tests on single microparticles with diameters ranging from 2 to 12 µm were performed using a nanoindenter. They revealed that the crushing force of both kinds of microparticles increased linearly with their diameter and that the adhesive loading reduced the mechanical strength of the prepared microparticles.

Optimisation of spray drying process conditions for sugar nanoporous microparticles (NPMPs) intended for inhalation

The present study investigated the effect of operating parameters of a laboratory spray dryer on powder characteristics, in order to optimise the production of trehalose and raffinose powders, intended to be used as carriers of biomolecules for inhalation.The sugars were spray dried from 80:20 methanol:n-butyl acetate (v/v) solutions using a Büchi Mini Spray dryer B-290. A 24 factorial design of experiment (DOE) was undertaken. Process parameters studied were inlet temperature, gas flow rate, feed solution flow rate (pump setting) and feed concentration. Resulting powders where characterised in terms of yield, particle size (PS), residual solvent content (RSC) and outlet temperature. An additional outcome evaluated was the specific surface area (SSA) (by BET gas adsorption), and a relation between SSA and the in vitro deposition of the sugar NPMPs powders was also investigated.The DOE resulted in well fitted models. The most significant factors affecting the characteristics of the NPMPs prepared, at a 95% confidence interval, were gas flow: yield, PS and SSA; pump setting: yield; inlet temperature: RSC.Raffinose NPMPs presented better characteristics than trehalose NPMPs in terms of their use for inhalation, since particles with larger surface area resulting in higher fine particle fraction can be produced.

Influence of spray-drying operating conditions on Rhamnus purshiana (Cáscara sagrada) extract powder physical properties

The aim of this work was to study Rhamnus purshiana (Cáscara sagrada) extract spray-drying in order to obtain powders with good rheological properties for direct compression (DC) and stability attributes. The experiments were carried out in a Büchi B-290 Mini Spray Dryer using colloidal silicon dioxide as carrier agent. A 2 5 − 1 fractional factorial statistical design was used to find adequate spray-drying operating conditions to produce Cáscara sagrada powders with good flow, good compactability properties, high process yield, low moisture content, low hygroscopicity, and caking tendency. Morphology, size, structural and thermal properties of the particles were also evaluated. The operating variables studied were air inlet temperature, atomization air flow rate, pump feed rate, aspiration capacity, and feed solids concentration. The 2 5 − 1 factorial experimental design used was a good strategy to establish spray-drying operating conditions to produce Cáscara sagrada extract powders with good properties for direct compression and high process yields. Colloidal silicon dioxide was an effective drying adjuvant. Its use in relatively high concentrations together with low atomization air flow rates improved powder flowability, increased the product's glass transition temperature, and decreased its moisture content and hygroscopicity.

Influence of emulsion composition and inlet air temperature on the microencapsulation of flaxseed oil by spray drying

The objective of this work was to study the influence of some process conditions on the microencapsulation of flaxseed oil by spray drying. The process was carried out on a mini spray dryer and gum Arabic was used as wall material. Seventeen tests were made, according to a central composite design. Independent variables were: inlet air temperature (138–202°C), total solid content (10–30% w/w) and oil concentration with respect to total solids (10–30% w/w). Encapsulation efficiency, lipid oxidation and powder bulk density were analyzed as responses. Powder morphology and particle size distribution were also analyzed. The feed emulsions were characterized with respect to droplet size and viscosity. Higher solid content and lower oil concentration led to higher encapsulation efficiency and lower lipid oxidation, which was related to the higher emulsion viscosity and lower droplets size. Increasing drying temperature resulted in higher lipid oxidation. Bulk density increased when higher solid content and lower inlet air temperature were used. The particles were rounded and shriveled, and their mean diameter was mainly affected by total solid content.

Cyclone selection influences protein damage during drying in a mini spray-dryer

The use of a small-dimensioned cyclone separator to spray-dry an aqueous solution of lysozyme on a mini spray-dryer produces consistently higher protein inactivation at all drying-air outlet temperatures examined between 50 °C and 105 °C. Differences in drying air flow rate through the machines will influence droplet/particle residence times within the drying chamber, but these are considered too small to explain the result. It appears more likely that a higher separation and retention of fines within the small cyclone causes higher measured protein inactivation. By virtue of their small size the fines have a greater specific surface area and suffer therefore a greater degree of protein damage when passing through the spray dryer from nozzle to collecting vessel. Although the dry powder yield is higher with the small-dimensioned cyclone than that obtained with the standard cyclone, the profile of residual moisture versus T outlet is irregular in shape. A possible lack of equilibrium between the attributes of the protein particles and the exhaust air needs therefore to be considered.

The Effect of Different Atomizing Gases and Drying Media on the Crystallization Behavior of Spray-Dried Powders

The use of different atomizing gases (N2 and CO2) was found not to alter the calorimetric behavior of the spray-dried powders significantly compared with air-atomized spray-dried powders in a Buchi B-290 (Postfach, Switzerland) mini spray dryer. However, the drying medium (N2 and CO2) was found to influence other powder properties, as seen from the alteration of morphology for the powders. An inert loop was attached to the dryer to recirculate the drying medium (N2 and CO2 gases) and to provide better control over the humidity of the drying medium by condensing the evaporated solvent. The degree of crystallinity of the spray-dried powder was measured using moisture-induced crystallization (a moisture sorption test) and modulated differential scanning calorimetry (MDSC). The sorption peak height was found to be lowest in the case of N2 gas (5 ± 1%, mean ± standard deviation, indicating more crystalline powder) and highest for CO2 gas (9.3 ± 0.1%, indicating more amorphous powder) compared with air (7.4 ± 0.3%). However, the MDSC analysis found that the thermal behavior did not vary significantly. It is suggested that the gases’ physical properties seem to be the main cause for some of these alterations in the product behavior. Different atomizing gases and gas media used during the spray-drying process can potentially be used to achieve different product behaviors.

Oral delivery of spray dried PLGA/amifostine nanoparticles.

Amifostine (Ethyol, WR-2721) is a cytoprotective drug approved by the US Food & Drug Administration for intravenous administration in cancer patients receiving radiation therapy and certain forms of chemotherapy. The primary objective of this project was to develop orally active amifostine nanoparticles using spray drying technique. Two different nanoparticle formulations (Amifostine-PLGA (0.4:1.0 and 1.0:1.0)) were prepared using a Buchi B191 Mini Spray Dryer. A water-in-oil emulsion of amifostine and PLGA (RG 502) was spray dried using an airflow of 600 L h(-1) and input temperature of 55 degrees C. A tissue distribution study in mice was conducted following oral administration of the formulation containing drug-polymer (0.4:1.0). The efficiency of encapsulation was 90% and 100%, respectively, for the two formulations while the median particle sizes were 257 and 240 nm, with 90% confidence between 182 and 417 nm. Since amifostine is metabolized to its active form, WR-1065, by intracellular alkaline phosphatase, the tissue levels of WR-1065 were measured, instead of WR-2721. WR-1065 was detected in significant amounts in all tissues, including bone marrow, jejunum and the kidneys, and there was some degree of selectivity in its distribution in various tissues. This work demonstrates the feasibility of developing an orally effective formulation of amifostine that can be used clinically.

Spray-Dried Pectic Polysaccharide Powders: Evaluation of Physicochemical Properties for Pharmaceutical Preparations

Pectic polysaccharide from durian rinds (Durio Zibethinus) has been reported to mainly compose of pectin which is generally used in various pharmaceutical dosage forms. The purpose of this research was to investigate the physicochemical properties of spray-dried pectic polysaccharide powders as a function of spray drying conditions (inlet temperature, feed rate, and aspirator rate) and formulation parameters (pectic polysaccharide concentration). A mini spray dryer was used to spray dry pectic polysaccharide in formulation with maltodextrin, colloidal silica and propylene glycol. Production yields were obtained between 31.08 – 52.87%. Higher yield percentage was obtained when the inlet temperature was increased. Particle size of < 7m was from low pectic polysaccharide concentration. The pectic polysaccharide powders were bulky and the shape was almost spherical with smooth surface but collapsed at high inlet temperature and low feed rate. At 75% RH and room temperature, the powders could adsorb moisture of about 12% of the powder weight. The swelling index and mucoadhesion time that the powders attached to the porcine intestine was ranged 14 – 70 and 7 - >30 minutes, respectively. This research provides useful information for development of pectic polysaccharide as fine powder for drug delivery.

An investigation into lactose crystallization under high temperature conditions during spray drying

Abstract Lactose crystallization was studied at high temperature conditions in a Buchi B-290 mini spray dryer. The inlet gas temperature was 200 °C, and an insulating material was used to reduce the heat loss from the drying chamber (outlet temperature 157 °C), thus increasing the gas and particle temperatures. At these conditions, lactose crystallinity was found to increase significantly compared with a case where it was spray dried at 170 °C in a non-insulated drying chamber (outlet temperature 90 °C), but the process yield was lower for the former case (0.16% yield) than for the low temperature conditions (47% yield). There is some evidence that high-temperature spray drying of lactose is more likely to give more β-lactose anomer. Different analytical techniques (Fourier Transform Infrared Spectroscopy, modulated differential scanning calorimetry, moisture sorption test, Raman spectroscopy) were used to investigate the degree of crystallization and possible lactose anomer formation during this spray drying at high inlet gas temperatures.

Influência da temperatura do ar de secagem e da concentração de agente carreador sobre as propriedades físico-químicas do suco de açaí em pó

The objective of this work was to study the influence of inlet air temperature and maltodextrin concentration on the physicochemical properties of acai juice powder produced by spray drying. The process was carried out in a mini spray dryer and the maltodextrin 10DE was used as carrier agent. Inlet air temperature varied from 138 to 202 °C and maltodextrin concentration varied from 10 to 30%. The characteristics analyzed were: moisture content, hygroscopicity, anthocyanin retention, color, particle size distribution, and morphology. The increase in the temperature resulted in particles with larger size, less moisture content, more hygroscopy and with lower anthocyanin retention, besides promoting a reduction in the color parameter L* and in the hue angle H*. The increase of maltodextrin concentration resulted in less hygroscopy, particles with larger size, , with higher luminosity (L*), lower C* values and higher H* values. With respect to morphology, the increase in the temperature led to the formation of a great number of particles with smooth surface, which is due to the higher heat transfer and, consequently, to the faster formation of a membrane around the atomized drop.

Comparison of physical and inhalation properties of spray-dried and micronized terbutaline sulphate

Terbutaline sulphate particles, for use in dry powder inhaler formulations, were prepared by spray-drying, using a Büchi 190 mini spray dryer. Spray-drying conditions were chosen to allow the production of spray-dried terbutaline sulphate with a size similar to micronized terbutaline sulphate, that is to say about 2.9 μm of volume mean diameter. The physical properties and in vitro inhalation behaviour of micronized and spray-dried terbutaline sulphate were compared. X-ray diffraction, DSC, SEM and laser size analysis were investigated. Spray-dying produced spherically shaped particles with amorphous structure. After blending with different lactoses, adhesion and aerodynamic properties were investigated. Evaluation of adhesion was carried out with a mechanical sieve and an Alpine air-jet sieve. The adhesion of terbutaline sulphate on the lactoses tested was lower in the case of the spray-dried drug. Aerodynamic evaluation of fine particle dose and emitted dose was conducted using a twin stage impactor. The emitted doses and the fine particle doses were higher with the spray-dried terbutaline sulphate. The Alpine air-jet sieve assays showed that there was a correlation between drug separation from a carrier by sieving and that obtained from longer in vitro deposition studies. There was a linear relationship between the adhesion characteristics and the fine particle dose.

Influence of process conditions on the physicochemical properties of açai ( Euterpe oleraceae Mart.) powder produced by spray drying

The objective of this work was to study the influence of spray drying conditions on the physicochemical properties of açai powder. The process was carried out on a mini spray dryer and maltodextrin 10DE was used as carrier agent. Seventeen tests were made, according to a central composite design. Independent variables were: inlet air temperature (138–202 °C), feed flow rate (5–25 g/min) and maltodextrin concentration (10–30%). Moisture content, hygroscopicity, process yield and anthocyanin retention were analysed as responses. Powder moisture content and process yield were positively affected by inlet air temperature and negatively affected by feed flow rate, which are directly related to heat and mass transfer. Process yield was also negatively influenced by maltodextrin concentration, due to the increase on mixture viscosity. Powders hygroscopicity decreased with increasing maltodextrin concentration, decreasing temperature and increasing feed flow rate. Powders with lower moisture content were more hygroscopic, which is related to the greater water concentration gradient between the product and the surrounding air. Anthocyanin retention was only affected by temperature, due to its high sensitivity. In respect to morphology, the particles produced at higher temperature were larger and a great number of them showed smooth surface.

The effect of the salt content on the crystallization behaviour and sorption fingerprints of spray-dried lactose

Different types of salts in various proportions affect lactose crystallization. In this study, two common monovalent salts, NaCl and KCl, were used at lactose:salt ratios of 5:2 and 5:1 (w/w) to observe the change in crystallization behaviour of the mixtures compared with that of pure lactose obtained from spray drying. The same operating conditions (170 °C inlet air temperature, 38 m 3/h main air flow rate, feed pump rate 11 ml/min, nozzle air flow rate of 473 L/h) were maintained for each run in a Buchi (B-290) Mini Spray Dryer to compare the behaviour of different feed compositions. To analyse the crystallization behaviour of each spray-dried product, Moisture Sorption Characteristic diagrams and Moisture Sorption Finger-prints were used, and Scanning Electron Microscopy (SEM) micrographs of the samples have also been carried out. The results show that, at lower salt contents (lactose:salt = 5:1), both lactose/salt mixtures showed the highest change in moisture content, but there was significant difference in sorption behaviour at higher salt contents for both salts. Among all the lactose/salt powders, the lactose:NaCl mixture at a ratio of 5:2 was found to be the most crystalline product in nature.