Spray-drying Technology Research Articles

Pharmaceutical aerosols for the treatment and prevention of Tuberculosis

Historically, pharmaceutical aerosols have been employed for the treatment of obstructive airway diseases, such as asthma and chronic obstructive pulmonary disease, but in the past decades their use has been expanded to treat lung infections associated with cystic fibrosis and other respiratory diseases. Tuberculosis (TB) is acquired after inhalation of aerosol droplets containing the bacilli from the cough of infected individuals. Even though TB affects other organs, the lungs are the primary site of infection, which makes the pulmonary route an ideal alternative route to administer vaccines or drug treatments. Optimization of formulations and delivery systems for anti-TB vaccines and drugs, as well as the proper selection of the animal model to evaluate those is of paramount importance if novel vaccines or drug treatments are to be successful. Pharmaceutical aerosols for patient use are generated from metered dose inhalers, nebulizers, and dry powder inhalers (DPIs). In addition to the advantages of providing more efficient delivery of the drug, low cost, and portability, pharmaceutical dry powder aerosols are more stable than inhalable liquid dosage forms and do not require refrigeration. Methods to manufacture dry powders in respirable sizes include micronization, spray drying, and other proprietary technologies. Inhalable dry powders are characterized in terms of their drug content, particle size, and dispersibility to ensure deposition in the appropriate lung region and effective aerosolization from the device. These methods will be illustrated as they were applied for the manufacture and characterization of powders containing anti-tubercular agents and vaccines for pulmonary administration. The influence of formulation, selection of animal model, method of aerosol generation, and administration on the efficacy demonstrated in a given study will be illustrated by the evaluation of pharmaceutical aerosols of anti-TB drugs and vaccines in guinea pigs by our group.

Fabrication and properties of W–20Cu alloy reinforced by titanium coated carbon fibers

Abstract Carbon fibers were coated with titanium by vacuum slow vapor deposition. W–20Cu composite powder was prepared by spray drying and calcining-continuous reduction technology. Titanium coated carbon fibers and W–20Cu composite powder were mixed by ball-milling in ethanol solution. This paper adopted spark plasma sintering process to prepare titanium coated carbon fibers/W–20Cu composites. Effects of doping amounts of titanium coated carbon fibers on the phases, microstructure and properties of the composites were investigated. Titanium coated carbon fibers/W–20Cu composites with improved mechanical properties and thermal conductivity were fabricated. Transverse rupture strength and thermal conductivity of the 1.0 wt.% titanium-coated carbon fibers/W–20Cu composites, compared with the monolithic W–20Cu alloy, were enhanced 33% and 36%, respectively. With small doping amount of titanium-coated carbon fibers, the composites without WC, W2C and graphite phases were obtained.

Production of Microencapsulated Crawfish (Procambarus clarkii) Astaxanthin in Oil by Spray Drying Technology

In this study, an emulsion prepared with flaxseed oil containing crawfish astaxanthin, sodium caseinate, lactose, and water was spray dried to produce microencapsulated flaxseed oil containing crawfish astaxanthin powder (MCA). Production rate and energy used to produce MCA were estimated. Physicochemical properties and storage stability of MCA were determined. The energy required to spray dry the microencapsulated flaxseed oil containing astaxanthin was 2.36 × 104 kJ/kg of emulsion. The microencapsulation efficiency for MCA was 86.06%, which indicated that more oil was encapsulated than on the particles’ surfaces. The particle size of MCA ranged from 6 to 100 µm. The astaxanthin concentration in MCA was 13.76 μg/g powder and alpha-linolenic acid (ALA) was the predominant fatty acid (53%) in MCA. Degradation of astaxanthin in MCA followed first-order reaction kinetics and could be well described by the Arrhenius equation. The astaxanthin in MCA was more stable when the powder was stored at 5°C than at 25 or 40°C.

Paclitaxel-loaded polyester nanoparticles prepared by spray-drying technology: in vitro bioactivity evaluation

Paclitaxel (PTX), an antimicrotubular agent used in the treatment of ovarian and breast cancer, was encapsulated in nanoparticles (NPs) of poly(lactide-co-glycolide) (PLGA) and poly(ε-caprolactone) (PCL) polymers using the spray-drying technique. Morphology, size distribution, drug encapsulation efficiency, thermal degradation and drug release were characterized. MCF7 cells were employed to evaluate the efficacy of the systems on cell cycle and cytotoxicity. The particle size was in the range 0.8–1 µm. The incorporation efficiency of PTX was more than 80% in all NPs obtained. In vitro drug release took place during 35 days, and drug release rates were in the order PCL > PLGA 50:50 > PLGA 75:25. Unloaded NPs showed to be cytocompatible at MCF7 cells. PTX-loaded NPs demonstrated the release of the drug block cells in the G2/M phase. All PTX-loaded formulations showed their efficacy in killing MCF7 cells, mainly PTX-loaded PLGA 50:50 and PLGA 75:25 that cause a decrease in cell viability lower than 20%.

Fabrication and characterization of spray dried Al 2O 3–ZrO 2–Y 2O 3 powders treated by calcining and plasma

In this paper, the Al 2O 3-20 wt.%ZrO 2 (8 wt.%Y 2O 3) feedstocks were fabricated and treated by spray drying, calcination, and plasma treatment technology. The morphology of feedstocks was characterized by scanning electron microscope (SEM). The phase structure and grain size were analyzed by X-Ray diffraction (XRD). The flowability and density were measured by Hall Flowmeter and density instrument, respectively. The sphericity and flowability of feedstocks treated by plasma flame increased greatly compared with that of the feedstocks without plasma treatment, and the particle surfaces were very smooth. The optimum flowability was obtained when the critical plasma spray parameter (CPSP) was 363. The compactness also increased greatly with the increment of CPSP, and the maximum value of compactness was got with CPSP of 325. Calcination can make the grain grow and plasma treatment can lead to the decrement of grain size. The phase structure of Al 2O 3 did not change, which was α-Al 2O 3 in the composites. The phase structure of ZrO 2 (8 wt.%Y 2O 3) changed from t-phase to c-phase which was affected greatly by plasma treatment.

Cover Caption

On the cover: Light microscopy image of emulsion containing purified menhaden fish oil and soluble rice bran fiber, “Microencapsulation of Menhaden Fish Oil Containing Soluble Rice Bran Fiber Using Spray Drying Technology” by Yuting Wan, Joseph David Bankston Jr, Peter J. Bechtel, and Subramaniam Sathivel; p E353.

New developments in dry powder pulmonary vaccine delivery

Pulmonary immunization has gained increased recognition as a means of triggering both a mucosal and systemic immune response without the use of needles. The appropriate formulation of antigens in a dry, solid state can result in improved stability, thereby removing cold-chain storage complications associated with conventional liquid-based vaccines. The particulate nature of dry powder vaccines could also induce a better immune response. This review describes our current understanding of pulmonary immunization, including possible barriers facing the development of pulmonary vaccines, and discusses recent advances in spray-drying technologies applicable to the production of dry powder formulations for pulmonary vaccine delivery.

Ultra-slow water diffusion in aqueous sucrose glasses

We present measurements of water uptake and release by single micrometre-sized aqueous sucrose particles. The experiments were performed in an electrodynamic balance where the particles can be stored contact-free in a temperature and humidity controlled chamber for several days. Aqueous sucrose particles react to a change in ambient humidity by absorbing/desorbing water from the gas phase. This water absorption (desorption) results in an increasing (decreasing) droplet size and a decreasing (increasing) solute concentration. Optical techniques were employed to follow minute changes of the droplet's size, with a sensitivity of 0.2 nm, as a result of changes in temperature or humidity. We exposed several particles either to humidity cycles (between ∼2% and 90%) at 291 K or to constant relative humidity and temperature conditions over long periods of time (up to several days) at temperatures ranging from 203 to 291 K. In doing so, a retarded water uptake and release at low relative humidities and/or low temperatures was observed. Under the conditions studied here, the kinetics of this water absorption/desorption process is controlled entirely by liquid-phase diffusion of water molecules. Hence, it is possible to derive the translational diffusion coefficient of water molecules, D(H(2)O,) from these data by simulating the growth or shrinkage of a particle with a liquid-phase diffusion model. Values for D(H(2)O)-values as low as 10(-24) m(2) s(-1) are determined using data at temperatures down to 203 K deep in the glassy state. From the experiment and modelling we can infer strong concentration gradients within a single particle including a glassy skin in the outer shells of the particle. Such glassy skins practically isolate the liquid core of a particle from the surrounding gas phase, resulting in extremely long equilibration times for such particles, caused by the strongly non-linear relationship between concentration and D(H(2)O). We present a new parameterization of D(H(2)O) that facilitates describing the stability of aqueous food and pharmaceutical formulations in the glassy state, the processing of amorphous aerosol particles in spray-drying technology, and the suppression of heterogeneous chemical reactions in glassy atmospheric aerosol particles.

Fabrication and characterization of porous silver powder prepared by spray drying and calcining technology

High porosity porous silver powder with about 100 µm average size and 5 µm pore size was fabricated by spray drying and calcining technology. Effects of calcining temperature and process of spray-dried powder on the phases, grain size, particle morphology and pore microstructure of silver powder were investigated. The results showed that porous silver with approximately spherical shape and via hole structure was obtained using 0.25 mol Ag 2CO 3 solution of ammonia water, which was spray-dried at 200 °C and calcined at 400 °C for 30 min with heat treatment technology curve of gradient temperature in air. And there were not Ag 2CO 3, Ag 2O and AgO phases existing in the porous silver. However, using 0.25 mol Ag 2CO 3 solution of ammonia water, the porous silver powder could not be fabricated by spray pyrolysis technology with a solution feed rate of 300 mL/h, flux of carrier gas of 0.30 MPa, and 640 °C furnace set temperature.

Development of Budesonide Microparticles Using Spray-Drying Technology for Pulmonary Administration: Design, Characterization, In Vitro Evaluation, and In Vivo Efficacy Study

The purpose of this research was to generate, characterize, and investigate the in vivo efficacy of budesonide (BUD) microparticles prepared by spray-drying technology with a potential application as carriers for pulmonary administration with sustained-release profile and improved respirable fraction. Microspheres and porous particles of chitosan (drug/chitosan, 1:2) were prepared by spray drying using optimized process parameters and were characterized for different physicochemical parameters. Mass median aerodynamic diameter and geometric standard deviation for conventional, microspheres, and porous particles formulations were 2.75, 4.60, and 4.30 microm and 2.56, 1.75, and 2.54, respectively. Pharmacokinetic study was performed in rats by intratracheal administration of either placebo or developed dry powder inhalation (DPI) formulation. Pharmacokinetic parameters were calculated (Ka, Ke, T(max), C(max), AUC, and Vd) and these results indicated that developed formulations extended half life compared to conventional formulation with onefold to fourfold improved local and systemic bioavailability. Estimates of relative bioavailability suggested that developed formulations have excellent lung deposition characteristics with extended T(1/2) from 9.4 to 14 h compared to conventional formulation. Anti-inflammatory activity of BUD and developed formulations was compared and found to be similar. Cytotoxicity was determined in A549 alveolar epithelial cell line and found to be not toxic. In vivo pulmonary deposition of developed conventional formulation was studied using gamma scintigraphy and results indicated potential in vitro-in vivo correlation in performance of conventional BUD DPI formulation. From the DPI formulation prepared with porous particles, the concentration of BUD increased fourfold in the lungs, indicating pulmonary targeting potential of developed formulations.

Preparation, characterization and in vitro intestinal absorption of a dry emulsion formulation containing atorvastatin calcium

A redispersible dry emulsion (DE) formulation of atorvastatin calcium (AC) was developed to enhance the in vitro dissolution of AC, thereby increasing its gastrointestinal absorption. The spray-drying technology was used where Plurol Oleique CC 497 was chosen as the oil phase. Effects of carriers, surfactants, and homogenizers on the characteristics of DE containing AC were systematically investigated. The final formulation consisted of dextrin and Poloxamer 188 as carrier and surfactant, respectively, and was homogenized by a high pressure homogenizer before spray drying. The in vitro release of AC from the optimized DE was significantly higher than that of pure AC powder (76% vs. 30% at 24 hr). The in vitro intestinal absorption of AC from the DE formulation was 0.77 μg/cm2 at 2 hr, which was a 2.33-fold increase compared to the pure unformulated AC powder. These results suggest that the oral dry emulsion formulation could improve the intestinal absorption of AC.

Spark plasma sintering of W–15Cu alloy from ultrafine composite powder prepared by spray drying and calcining-continuous reduction technology

Abstract The effects of spark plasma sintering and conventional H 2 atmosphere sintering on the microstructure and properties of W–15Cu alloy using ultrafine W–15Cu composite powder fabricated by spray drying and calcining-continuous reduction technology were investigated. Results showed that W–15Cu alloy, consolidated by spark plasma sintering for 10 min at 1200 °C under a pressure of 30 MPa, with 98% relative density, transverse rupture strength 1259 MPa, Vickers hardness 379, average grain size 0.8 µm and thermal conductivity 189 W/m K, was obtained. In comparison to the conventional H 2 atmosphere sintering process, spark plasma sintering to W–15Cu alloy could be achieved at lower sintering temperature and shorter sintering time. Furthermore, better properties in spark plasma sintered compacts were obtained, moreover spark plasma sintering resulted in finer microstructure.

Evaluation of the effects of lactose on the surface properties of alginate coated trandolapril particles prepared by a spray-drying method

This preliminary work involved a comparison of untreated microcrystals, alginate-based spray-dried microparticles, and alginate-based lactose containing spray-dried of the antihypertensive drug, trandolapril. Physicochemical properties, such as surface free energy, the polarity and the dissolution profiles of the untreated drug and the spray-dried particles were investigated. The main objective was the separation of crystals suitable for the production of intermediates for high-speed tablet-making from materials with low melting point. The aim was to modify the surface properties of trandolapril without changing the dissolution profile of the active agent; this was achieved by the application of spray-drying technology for the production of coated particles with a hydrophilic surface in order to attain better wetting properties, and better processibility. The aggregation of the spray-dried coated particles and their subsequent coalescence is very favourable for the liquid containing lactose. The kinetics of dissolution of the active ingredient was not changed appreciably by the surface modification obtained by spray-drying, regardless of whether alginate or alginate and lactose was used. Slightly quicker dissolution was observed for the sample containing lactose. The spray-drying with alginate increased the polarity of the surface of the particles. The application of lactose caused a more marked increase in this property; and this can be a very useful way to produce a powder mixture containing polar components (e.g. lactose). Thus, the spray-drying method is a very suitable procedure for the preparation of coated crystals as intermediates for tablet-making. The evaluation of the surface properties of these particles can promote an understanding of the production process and optimization of the composition.

Monodisperse Droplet Generators as Potential Atomizers for Spray Drying Technology

Spray drying is a widely used unit operation for manufacturing powders of different characteristics. Many technological improvements have been made in the last few decades, and a great amount of research work is still being conducted. Recently, the hybrid spray-drying technique was reported, which combines the ink-jet technology with spray drying in order to produce particles of uniform characteristics.[ 1-4 ] The monodisperse droplet generators (MDGs) have certain features that make them attractive for use as atomizers in spray-drying operations. In this article, a comprehensive introduction to a variety of monodisperse droplet generators is provided. The advantages and limitations of these generators are discussed. The fundamental equations for predictions of the average droplet size are summarized. The discussion given in this study is aimed at the development of a hybrid technology that marries a suitable MDG with the existing spray-dryer technique (yet with some modifications) to manufacture the product with uniform characteristics containing micro- to nanosized particles.

Characterization of W–20Cu ultrafine composite powder prepared by spray drying and calcining-continuous reduction technology

W–20Cu ultrafine composite powder, whose average grain size was about 500 nm, was fabricated by spray drying and calcining-continuous reduction technology. In the W–20Cu ultrafine powder the nanocrystalline Cu grain can wet W grain by the CuO transitional layer, the special non-metal–metal nanocomposite structure would play very important roles in obtaining W–Cu alloy with good mechanical properties, thermal conductivity and homogeneous microstructure.

Spray-Dried Powders for Pulmonary Drug Delivery

Powders for inhalation are traditionally prepared using a destructive micronization process such as jet milling to reduce the particle size of the drug to 2-5 mum. The resultant particles are typically highly cohesive and display poor aerosolization properties, necessitating the addition of a coarse carrier particle to the micronized drug to improve powder flowability. Spray-drying technology offers an alternative, constructive particle production technique to the traditional destructive approach, which may be particularly useful when processing biotechnology products that could be adversely affected by high-energy micronization processes. Advantages of spray drying include the ability to incorporate a wide range of excipients into the spray-drying feedstock, which could modify the aerosolization and stability characterizations of the resultant powders, as well as modify the drug release and absorption profiles following inhalation. This review discusses some of the reasons why pulmonary drug delivery is becoming an increasingly popular route of administration and describes the various investigations that have been undertaken in the preparation of spray-dried powders for pulmonary drug delivery.

Spray-drying technology for the synthesis of nanosized LiMn 2O 4 cathode material

Spinel LiMn 2O 4 cathode material has been synthesized by a spray-drying method for lithium ion batteries. During the entire process, the as-prepared powders were characterized using TGA/DTA, XRD, FTIR, SEM and TEM. The results showed that this method not only reduces the sintering time to 5 h at 750 °C, but also decreases the average particle size of LiMn 2O 4 powders to the order of nanometers. The electrochemical performance of nanosized LiMn 2O 4 was investigated by the galvanostatic charge–discharge tests. The data indicate that the nanosized LiMn 2O 4 has a specific capacity of about 130 mA h g − 1 (1/5 C), and at higher rate (1 C), still has good cycling stability.

Design and Operation of a Spray Dryer for the Manufacture of Hollow Microparticles

Spray-drying technology is used in a wide variety of processes ranging from manufacture of food products to pharmaceuticals. Most recently, spray-drying technology has also been explored to make hollow microparticles. This work presents an approach that designs a spray-drying chamber using a rate-based description combined with a droplet size distribution model. The major criterion in the design is the desired moisture content of the final particle. The predictions of the final particle properties are compared to experimental data obtained from a laboratory spray-drying unit. The results show that the final spray-drying design is sensitive to liquid feed flow rate, inlet drying gas temperature, and heat loss.

Effect of calcium promoter on a precipitated iron–manganese catalyst for Fischer–Tropsch synthesis

A series of precipitated Fe/Mn Fischer–Tropsch synthesis (FTS) catalysts incorporated with calcium promoter were prepared by the combination of co-precipitation and spray-drying technology. The catalysts were characterized by using N 2 physisorption, CO 2 temperature-programmed desorption and Mössbauer spectroscopy methods. FTS performances of the catalysts were tested in a 1 dm 3 continuous stirred tank reactor. It is found that calcium promoter has negligible effect on the textural properties, and the addition of calcium promoter can enhance the surface basicity of the catalyst. An appropriate amount of calcium promoter can promote the reduction and carburization of the catalysts during the reduction and Fischer–Tropsch synthesis (FTS) reaction in syngas, but the excessive addition of calcium promoter will decrease the extent of reduction and carburization. The reaction results indicated that the activities of both FTS and water-gas shift (WGS) decrease with the incorporation of calcium promoter. Calcium promoter can inhibit the hydrogenation ability, suppress the formation of methane, and enhance the selectivities to olefin and higher molecular weight products.

Formulating Drug Delivery Systems by Spray Drying

The knowledge of the potential use of the spray-drying technology to prepare microparticulate drug delivery systems—microspheres and microcapsules—has been strongly improved over the last years. Various microparticulate spray drying systems used as vehicles for drug encapsulation and delivery that have been investigated for different purposes are presented here, including spray-dried powders formulated with hydrophilic polymers allowing controlled drug release, biodegradable microspheres prepared from aqueous systems, and spray-dried silica gel microspheres.