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PubMed2002

CNS activities of liquid and spray-dried extracts from Lippia alba-Verbenaceae (Brazilian false melissa).

The CNS activity of Lippia alba liquid and spray-dried extracts, containing the non-volatile fraction from the leaves, was investigated. L. alba liquid extracts were prepared by percolation with EtOH 40, 60 or 80%. The liquid extracts, named ES(40%,) ES(60%) and ES(80%,) were concentrated, the ethanol eliminated and then tested in Swiss mice to evaluate its sedative and anticonvulsant effects. The animals received the extracts, orally, in doses corresponding to 200 mg of dry residue by kilogram of body weight. All mice were evaluated in the barbiturate-induced sleep test. Similarly, other groups of mice were submitted to convulsions induced by pentylenetetrazol (PTZ). The concentrated extract obtained from ES(80%) showed the most significant sedative and myorelaxant effects as well as the highest total flavonoid content (66 mg/100 g, expressed in apigenin). Two spray-dried powders, SDP(1) and SDP(2), were prepared from ES(80%) using as excipients, respectively, colloidal silicon dioxide (CSD) and CSD associated to beta-cyclodextrin. Only SDP(1) showed sedative profile similar to that presented by ES(80). In conclusion, we demonstrated that the non-volatile fraction of L. alba, extracted in ethanol 80% (v/v), presents sedative and myorelaxant effects and that, among the tested extracts, this presents the highest flavonoid content. We demonstrated also the technological feasibility of spray-dried extracts and the influence of the excipient on its sedative properties.

Animals↗
PubMed2001

Encapsulation of orange oil in a spray dried double emulsion.

Encapsulation is an important technique being used to protect sensitive food materials like flavours from deterioration. The capsule wall isolates them from the atmospheric oxygen, moisture, temperature and light. Encapsulation also masks some objectionable flavours, e.g. fish oil and some bitter antibiotics. In this study orange oil was encapsulated in the inner compartment of a double emulsion belonging to the type O1-W-O2 where O1 is orange oil, W is water and O2 is vegetable oil. In order to make orange oil double emulsion suitable for use in dry mixes, it was secondarily coated with wall materials of lactose and caseinate using spray drying technique. Entrapment of orange oil in such structure is also expected to slow down the release of volatiles and guarantee more protection for orange oil against atmospheric conditions. This method may have a potential application in different types of food or pharmaceutical products where maximum protection for flavours or slow release are required. This study includes detailed preparation of the spray dried double emulsion, evaluation of the encapsulation efficiency using light and scanning electron microscope and calculation of the yield percent of the encapsulated oil. In a separate paper we will examine the efficiency of spray dried double emulsion to control the release of orange oil by GC.

Capsules↗
PubMed1987

Enhancement of the dissolution rate of a poorly water-soluble drug (tolbutamide) by a spray-drying solvent deposition method and disintegrants.

The dissolution rate of a poorly water-soluble drug, tolbutamide, was improved by spray-drying a diluted ammonia solution of the drug containing either a low-substituted hydroxypropylcellulose (L-HPC) or partly pregelatinized corn starch (PCS) as disintegrants. With L-HPC the resultant particles were agglomerates of disintegrant with drug on the surface and within the particles, while particles formed with PCS were composed of a single core of PCS on which the drug was deposited. The deposited drug crystals were very fine because the rapid solvent evaporation restricted crystal growth. The spray-dried particles prepared with PCS had a structure similar to that of an ordered mix. The drug dissolution rate from the spray-dried particles was more rapid than that of the powdered drug alone or with disintegrant and could be attributed to separation of the layer of fine drug crystals from the surface of the particles by swelling of disintegrant. PCS enhanced the drug dissolution rate compared with systems using corn starch. The dissolution rate also depended on the drug content of the particles which was higher than that in ordered mixtures or conventional solvent deposition systems. This system described also had the advantage of avoiding the use of organic solvents.

Chemical Phenomena↗
PubMed2000

In vitro evaluation of sol-gel processed spray dried silica gel microspheres as carrier in controlled drug delivery.

The objective of this study was to evaluate sol-gel-derived spray dried silica gel microspheres as carrier material for dexmedetomidine HCl and toremifene citrate. The drug was dissolved in sol-gel processed silica sol before spray drying with Büchi laboratory scale equipment. Microspheres with a low specific surface area were spherical by shape with a smooth surface without pores on the external surface. The particle size distribution was quite narrow. The in vitro release of toremifene citrate and dexmedetomidine HCl showed a dose-dependent burst followed by a slower release phase, that was proportional to the drug concentration in the concentration range between 3.9 and 15.4 wt.%. The release period for toremifene citrate was approximately 10 days and for dexmedetomidine HCl between 7 and 50 days depending on drug concentration. Spray drying is a promising way to produce spherical silica gel particles with a narrow particle size range for controlled delivery of toremifene citrate and dexmedetomidine HCl.

Delayed-Action Preparations↗
PubMed2006

Spray-dried microparticles containing polymeric nanocapsules: formulation aspects, liquid phase interactions and particles characteristics.

Up to now, the full potential of polymer-based nanoparticles is not yet exploited because of a lack of stability when conserved in aqueous medium. The present paper reports the water elimination from nanocapsules (NC) dispersions by means of the spray-drying technique with the aim to achieve dried solid forms of interest using colloidal silicon dioxide as drying auxiliary. The influence of formulation parameters on the suspension behaviour and on the powders characteristics was also evaluated. Our findings demonstrated that the mixing protocol, the concentrations of both NC and silica are crucial parameters that affect the feed behaviour and the spray-dried particles characteristics. Interactions occurring in the feed are directed by hydrogen bounds and were more sensitive to the silica concentration than that of NC as evidenced by rheological measurements. The NC are entrapped within solid dried matrixes following their interaction with silica particles in the feed. SEM analyses of the obtained powders showed spherical separated microparticles formed by the association of NC and silica when they are mixed at adequate concentrations in the feed before spray-drying. On the other hand, fused agglomerated particles presenting NC at their surface, characterised by irregular shapes and a strong adhesiveness were prepared when the silica concentration was not sufficient. The surface composition of the spray-dried powders was investigated using the ESCA technique and revealed the NC exclusion from the surface to obtain powders suitable for further handling.

Chemistry, Pharmaceutical↗
PubMed2004

Compression behaviour and tablet-forming ability of spray-dried amorphous composite particles.

The aim of this study was to investigate the compression behaviour and tablet-forming ability of spray-dried amorphous two- and three-component composite particles. Particles of lactose alone, two-component particles of lactose and PVP, and three-component particles of lactose, PVP and a small amount of polysorbate 80 were prepared by spray-drying. Two qualities of PVP with different molecular weights were used for the preparation of both types of particles. The particles were characterised with respect to permeametry surface area, moisture content, particle and bulk density, glass transition and crystallisation temperature, and heat of crystallisation. The tablet tensile strength of the different particles formed at a series of applied pressures was determined and compression parameters were derived from the Heckel and Kawakita equations. The presence of PVP gave particles that were less prone to deform permanently during compression while the presence of surfactant gave particles that were less able to form tablets. In conclusion, the compression behaviour and tablet-forming ability of spray-dried amorphous lactose can be modulated by the addition of stabilising polymers or surfactants to the spray feed solution.

Compressive Strength↗
PubMed2004

Supplementation and delivery of n-3 fatty acids through spray-dried milk reduce serum and liver lipids in rats.

Indian diets comprising staples such as cereals, millets, and pulses provide 4.8 energy % from linoleic acid (18:2n-6) but fail to deliver adequate amounts of n-3 FA. Consumption of long-chain n-3 PUFA such as EPA (20:5n-3) and DHA (22:6n-3) is restricted to those who consume fish. The majority of the Indian population, however, are vegetarians needing additional dietary sources of n-3 PUFA. The present work was designed to use n-3 FA-enriched spray-dried milk powder to provide n-3 FA. Whole milk was supplemented with linseed oil to provide alpha-linolenic acid (LNA, 18:3n-3), with fish oil to provide EPA and DHA, or with groundnut oil (GNO), which is devoid of n-3 PUFA, and then spray-dried. Male Wistar rats were fed the spray-dried milk formulations for 60 d. The rats given formulations containing n-3 FA showed significant increases (P < 0.001) in the levels of LNA or EPA/DHA in the serum and in tissue lipids as compared with those fed the GNO control formulation. Rats fed formulations containing n-3 FA had 30-35% lower levels of serum total cholesterol and 25-30% lower levels of serum TAG than control animals. Total cholesterol and TAG in the livers of rats fed the formulations containing n-3 FA were lower by 18-30% and 11-18%, respectively, compared with control animals. This study showed that spray-dried milk formulations supplemented with n-3 FA are an effective means of improving dietary n-3 FA intake, which may decrease the risk factors associated with cardiovascular disease.

Animals↗
PubMed2000

Production of Eudragit microparticles by spray-drying technique: influence of experimental parameters on morphological and dimensional characteristics.

The aim of this study was to evaluate the influence of operating parameters on the characteristics of methacrylate microparticles prepared by spray-drying technique. Eudragit microparticles were prepared by a spray-drying method. The influence of different experimental parameters (i.e., solvent, feed rate, air flow rate, air-drying temperature, and aspiration flow rate) on microparticle morphology, size distribution, and recovery was studied. In addition, different Eudragit types and Eudragit RS concentrations were employed. Optical and electron microscopy were employed to analyze microparticle morphology and dimensional distribution. Finally, prednisolone as model drug was encapsulated in Eudragit RS microparticles. Low feed rate values yielded the best results in terms of microparticle morphology. Changes in nebulizing air flow did not result in a corresponding effect on microparticle characteristics. An increase of air-drying temperature resulted in a reduction of microparticle dimension and recovery. A low flow of drying air was preferable because this resulted in microparticles with an optimal morphology. The polymer concentration affected both morphology and dimensions of microparticles. The encapsulation of prednisolone led to good incorporation efficiencies without altering percentage of recovery, morphology, and mean dimension of the microparticles. The selection of appropriate parameters yielded spray-dried Eudragit RS microparticles characterized by good morphology and narrow dimensional distribution.

Acrylates↗
PubMed2000

Parameters influencing the antigen release from spray-dried poly(DL-lactide) microparticles.

Microparticles were produced by spray-drying from a high molecular weight polylactide (PLA R207) for the development of long-lasting controlled release systems of vaccines, which may be designed to obviate the need for booster doses. The current investigation considered the effect of both technological parameters (inlet air temperature and spray rate of feed) and polymeric solutions (polymer concentration and nature of organic solvents) on characteristics of microparticles (morphology, size and antigen loading) containing a water-soluble model antigen (bovine serum albumin, BSA). Following parameters chosen, microparticles were characterized by a mean size from 3.08 +/- 0.06 to 9.43 +/- 0.26 microm and a BSA loading from 2.45 +/- 0.13 to 18.20 +/- 2.25% (w/w). The BSA release rate from microparticles varied from 11.17 +/- 2.20 to 92.60 +/- 3.46% in 24 h. The modification of the inlet temperature, the spray-rate of feed or the use of a mixture of dichloromethane/chloroform (DCM/CFM) instead of DCM alone resulted in the modification of the BSA burst release. This burst release was followed by a BSA release rate slower for microparticles with a low BSA loading. Moreover, the increase of the R207 concentration resulted in a decrease of the BSA release rate while the burst release was not modified. SDS-PAGE electrophoresis and isoelectric focusing analyses of the BSA released from microparticles confirmed the preservation of its physicochemical characteristics. Together, results showed that the spray-dried microparticles loaded with hydrophilic antigen could be used as a potential delivery system for the long-lasting controlled release of vaccines.

Antigens↗
PubMed2000

Development of spray-dried acetaminophen microparticles using experimental designs.

Experimental factorial designs were built to investigate the effects of five parameters on production yields and moisture contents of spray-dried products. These factors concerned both the solution feed (drug concentration, colloidal silica concentration and polymer/drug ratio) and the spray dryer (inlet temperature and feed rate). Three formulations containing cellulose derivatives and acetaminophen were tested. The aim of the study was to optimize the operating conditions to maximize production yields while minimizing moisture contents. First screening experiments consisting of fractional factorial designs revealed the most significant factors to be inlet temperature, feed rate and their interaction for both formulations containing sodium carboxymethylcellulose and feed rate and colloidal silica concentration for the formulation containing microcrystalline cellulose. Then, the optimal operating conditions were estimated by response surface methodology. Central rotational composite designs showed quadratic models were adequate. New assays were carried out using these last conditions to evaluate both the repeatability and reproducibility of the spray-drying technique. Yields above 80% and moisture content of approximately 1% were reached. The characterization of microparticles revealed the poor flowability of the spray-dried products due to significant cohesiveness and very small size (less than 55 microm).

Acetaminophen↗
PubMed2003

Change in secondary structure of silk fibroin during preparation of its microspheres by spray-drying and exposure to humid atmosphere.

Silk microspheres prepared by spray-drying were exposed to humid atmosphere (89% relative humidity, RH). Change in the secondary structure of silk fibroin during preparation of silk microspheres and exposure to high humidity was studied. Scoured silk fiber was dissolved in an aqueous solution of calcium chloride mixed with ethanol. After dialysis against purified water, theophylline was added to the solution as a model drug. Silk microspheres were obtained by spray-drying. Silk fibroin and theophylline were found to be amorphous in the microsphere by means of powder X-ray diffractometry. Fibroin assumed a beta-sheet conformation in the scoured silk fiber while it has an irregular structure in the microsphere, according to FTIR and Raman spectra. Fibroin recrystallized and its secondary structure changed to beta-sheet conformation by exposure of the microspheres to an atmosphere of 89% RH.

Fibroins↗
PubMed1998

Spray-drying performance of a bench-top spray dryer for protein aerosol powder preparation.

The objective of this work was to improve a bench-top spray dryer's efficiency in both production recovery and throughput for preparing protein aerosol powders. A Büchi mini-spray dryer was used to prepare the powders of recombinant humanized anti-IgE antibody. The resulting powder's physical properties such as particle size, residual moisture, and morphology, along with its recovery and production rate was the basis of this development work. Mass balance suggests that approximately 10-20% of powder was lost in the exhaust air, consisting primarily of particles less than 2 micrometer. Also, significant loss (20-30%) occurred in the cyclone. Attempts were made to improve product recovery in the receiving vessel using dual-cyclone configurations, different cyclone designs, cyclones with anti-static treatment, and different receiver designs. System modifications such as replacing the original bag-filter unit with a vacuum system effectively reduced drying air flow resistance, allowing the protein to be dried at a lower inlet air temperature and the production scale to be increased. We concluded that the modified spray-drying system is advantageous over the original bench-top spray dryer. This improvement will be beneficial to early-stage research and development involving high-valued protein powders.

Aerosols↗
PubMed2001

Stabilization of Penicillium occitanis cellulases by spray drying in presence of Maltodextrin.

The stabilization of fungal cellulases by spray drying, the thermal stability of Penicillium occitanis cellulases and the effect of some additives were studied. We observed that CMCase activity presents a good stability at 50 degrees C, even after 60 h of incubation. On the other hand, beta-glucosidase activity was more sensitive (loss of 50%) and reacts on total cellulases activities (Filter paper activities). The addition of hydrophilic agents such as ethylene glycol, polyethylene glycol (PEG6000) enhanced enzyme activity. The effect of PEG and Maltodextrin, another water activity decreasing agent, were then tested during the spray drying of Pol6 cellulases. The presence of 1% PEG allowed the best recovery but had a negative effect on enzyme stability while 1% Maltodextrin showed a negative effect on enzyme recovery but a very positive effect on enzyme stabilization.

Journal Article↗
PubMedDate not supplied

Optimizing formulation factors in preparing chitosan microparticles by spray-drying method.

The chitosan only, chitosan/Pluronic F68, chitosan/gelatin, chitosan/Pluronic F68/gelatin microparticles and betamethasone-loaded chitosan/Pluronic F68/gelatin microparticles were successfully prepared by a spray-drying method. Microparticle characteristics (yield rate, zeta potential, particle size and tap density), loading efficiencies, microparticle morphology and in-vitro release properties were investigated. By properly choosing excipient type, concentration and varying the spray-drying parameters, a high degree of control was achieved over the physical properties of the dry chitosan powders. SEM micrograph shows that the particle sizes of the varied chitosan composed microparticles ranged from 2.12-5.67 microm and the external surfaces appear smooth. Using betamethasone as model drug, the spray-drying is a promising way to produce good spherical and smooth surface microparticles with a narrow particle size range for controlled delivery of betamethasone. The positively charged betamethasone-loaded microparticles entrapped in the chitosan/Pluronic F68/gelatin microparticles with trapping efficiencies up to 94.5%, yield rate 42.5% and mean particle size 5.64 microm varied between 4.32-6.20 microm and tap densities 0.128 g/cm(3). The pH of particle was increased with increasing betamethasone-loaded amount, but both zeta potential and tap density of the particles decreased with increasing betamethasone-loaded amount. The betamethasone release rates from chitosan/Pluronic F68/gelatin microparticles were influenced by the drug/polymer ratio in the manner that an increase in the release% and burst release% was observed when the drug loading was decreased. The in vitro release of betamethasone showed a dose-dependent burst followed by a slower release phase that was proportional to the drug concentration in the concentration range between 14-44%w/w.

Betamethasone↗
PubMed2001

The spray drying of acetazolamide as method to modify crystal properties and to improve compression behaviour.

Acetazolamide shows a very poor compression ability and tablets must usually be produced through a wet granulation process. However, the possibility to obtain pure acetazolamide for direct compression could be interesting for industrial application. With the scope to obtain a material for direct compression, three different crystallisation methods were chosen, with respect to acetazolamide solvent solubility. (a) Acetazolamide was dissolved in an ammonia solution and then spray dried. It was possible to characterise the spherical particles as a mixture of two polymorphic forms, I and II by Powder X-ray diffraction study. (b) Pure form I was obtained by slowly cooling to room temperature a boiling water solution. (c) Pure form II, the marketed form, was obtained by neutralisation of an ammonia solution. Their compression behaviour was investigated firstly by a rotary press. Whilst pure polymorphic forms I and II could not be compressed, the spray dried particles showed very good compression properties. In fact, tablets were obtained only by spray dried particles, which show very good properties under compression and the absence of capping tendency. On the other hand, it was impossible to obtain tablets from polymorphic forms I and II, whatever compression pressures were used. In order to explain their densification mechanism, a single-punch tablet machine, equipped for the measurement of the upper punch displacement in the die, was used. From calculated Heckel's parameters, it was demonstrated that the spray dried material shows a greater particle rearrangement in the initial stage of compression due to its spherical habit and minor wrinkledness of particle surface. The crystalline structure due to the presence of polymorphic forms I and II concur to lowering the intrinsic elasticity of the material. This fact avoids the risk of the rupturing the interpaticulate bonds, which are formed during the compression, concurring to the consolidation of the tablet.

Acetazolamide↗
PubMed1977

[Destruction of Microbacterium lacticum, Escherichia coli and Staphylococcus aureus in milk by spray-drying. I. Selective count of surviving bacteria].

In this paper a method which allows the measure of microbial death rate during spray-drying by means of a streptomycin-resistant mutant that can be grown on a streptomycin-containing agar is described. Plate counts of Microbacterium lacticum, Escherichia coli, and Staphylococcus aureus recovered from skim milk powders were done on plate count agar in the presence and absence of streptomycin and on various selective media. The powders were produced from evaporated milk previously inoculated with those organisms. Our results showed that the proposed method allows the recovery of 78% of M. lacticum, 61% of E. coli, and 100% of S. aureus that survived spray-drying. Recoveries of surviving E. coli on violet bile agar and brilliant green bile 2% were 34% and 29% respectively. Baird-Parker and mannitol salt agar media allow the recovery of all surviving S. aureus, thus showing that S. aureus cells did not lose their ability to grow in media containig 7.5% NaCl. Our results show that physiological injury of the cells during spray-drying differs from injury due to heating only.

Actinomycetales↗
PubMed2003

Carbamazepine/betaCD/HPMC solid dispersions. I. Influence of the spray-drying process and betaCD/HPMC on the drug dissolution profile.

The aim of this study was to compare carbamazepine (CBZ) solid dispersions prepared by spray-drying of aqueous dispersions with the corresponding physical mixtures. The influence of the association of beta-cyclodextrin (betaCD) and hydroxypropyl methylcellulose (HPMC) on the CBZ dissolution profile of the preparations was investigated. Results demonstrated that CBZ release from solid dispersions is dependent on the ratio of betaCD and HPMC. The spray-drying process confers better homogeneity to CBZ polymeric dispersions than the physical mixture process. In summary, we demonstrated the feasibility of obtaining a homogeneous polymeric solid dispersion of CBZ from an aqueous media by spray-drying and a clear influence of the betaCD:HPMC ratio on the release profile of CBZ.

Anticonvulsants↗
PubMed2005

Aqueous two-phase systems as a formulation concept for spray-dried protein.

This study investigates to what extent an aqueous two-phase system (ATPS) can encapsulate and protect the secondary structure of a protein during spray drying. The ATPSs contained polyvinyl alcohol (PVA) and dextran solutions, in different proportions. A model protein, bovine serum albumin (BSA) and, in some experiments, trehalose were added to the ATPS prior to spray drying. Electron spectroscopy for chemical analysis (ESCA), differential scanning calorimetry (DSC), UV spectrophotometry, size exclusion high-performance liquid chromatography (SEC-HPLC) and Fourier transform infrared spectroscopy (FTIR) were used for analysis of solid and reconstituted samples. The anticipated function of the ATPS was to improve the stability of the protein by preventing interactions with the air-liquid interface during drying and by improving the encapsulation of the protein in the dried powder. BSA was found to preferentially partition to the dextran phase and in the absence of PVA, BSA dominated the powder surface. In samples containing PVA, the polymer mainly covered the powder surface, even though the dextran-rich phase was continuous, thus preventing protein surface interactions and providing improved encapsulation. However, PVA was found to cause partial loss of the native structure of BSA although the protein was well encapsulated during spray drying.

Animals↗