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PubMed1980

Preparation of enteric-coated microcapsules for tableting by spray-drying technique and in vitro simulation of drug release from the tablet in GI tract.

Improved methods were developed for the preparation of enteric-coated microcapsules for tableting by a spray-drying technique, and the drug release behavior from the tableted microcapsules was investigated using a disintegration apparatus and a new in vitro method of simulating the GI tract. As a model system, ammonium solutions of sulfamethoxazole and cellulose acetate phthalate were spray dried using a centrifugal wheel atomizer at 140 degrees. Additives such as colloidal silica, montmorillonite clay, and talc were included in the formulations for spray drying. The influence of the additives on the particle diameter, density, packing properties, and compressibility of the product and on the release characteristics of the resultant tablet in vitro were investigated. The additives in the formulations greatly improved the flow properties of the spray-dried products, which could be tableted easily. Products from the nonadditive formulations could not be tableted due to their poor flowability. The hardness and disintegration rate of the tablet increased with increasing concentration of additives in the formulations. X-ray analysis and IR spectroscopy confirmed that the crystals of sulfamethoxazole in the spray-dried microcapsules with cellulose acetate phthalate were converted from Form I to Form II. In vitro release characteristics of the tablets were studied using a disintegrator (JP) in buffer solutions (pH 1.2 and 7.5) and distilled water. Enteric action of the spray-dried products was proved by comparison with the original nontreated powders. The additives in the tablet increased the release rate at the initial stage in all dissolution media used. A new in vitro release simulator was devised consisting of a flow-type dissolution container in which the pH of the medium was changed continuously from 1.2 to 7.0 to simulate the pH change of tablets exposed to the GI tract.

Chemical Phenomena↗
PubMed2004

Aerosol dispersion of respirable particles in narrow size distributions produced by jet-milling and spray-drying techniques.

PURPOSE: To examine the effect of particle size and morphology on aerosol dispersion using jet-milled and spray-dried mannitol particles in narrow size distributions within the respirable range. METHODS: Particle size and morphology were examined by laser diffraction and scanning electron microscopy, respectively. Aerosol dispersion was examined using a cascade impactor with a preseparator operating at a flow rate of 60 L/min, using two inhaler devices: Rotahaler (low-resistance device) and Inhalator (high-resistance device). Powder flow was examined using static and dynamic methods (Carr's compressibility index and vibrating spatula, respectively). RESULTS: Narrow size distributions of jet-milled and spray-dried particles were produced (d50% = 1.4 to 10.3 microm, GSD = 1.8 to 2.1, and d50% = 1.6 to 7.5 microm; GSD = 1.5 to 1.9, respectively). All particles were highly crystalline. Differences in particle shape were observed between jet-milled and spray-dried particles. Higher fine particle fraction (FPF) and relative fine particle fraction (FPFrel) (greater aerosol dispersion) and lower geometric standard deviation (GSD) (less variation) were obtained using particles with d50% between 2 and 5 microm. Higher mass median aerodynamic diameter were obtained with larger d50%. Spray-dried particles produced greater aerosol dispersion compared with jet-milled particles. Greater aerosol dispersion was obtained using the Inhalator than the Rotahaler. CONCLUSIONS: Small changes in the particle size within the 1-10-microm range produced a major impact in the aerosol dispersion of jet-milled and spray-dried particles. Even in these narrow size ranges, aggregation plays an important role in aerosol dispersion.

Administration, Inhalation↗
PubMed1998

Evaluation of atomizer performance in production of respirable spray-dried particles.

The purpose of this study was to analyze atomizer performance in the production of respirable spray-dried particles. An ultrasonic nebulizer and a plain-jet airblast atomizer were evaluated in an open cycle, cocurrent spray-drying tower using a 0.5% w/v disodium fluorescein solution. The plain-jet airblast atomizer produced smaller initial droplet sizes (D32 = 4.5-4.8 microns) relative to the ultrasonic nebulizer (D32 = 20-48 microns) over a range of atomizer operating conditions. The airblast atomizer was selected for further analysis in two spray-drying tower configurations: grounded and electrostatically charged. The spray-dried particles produced by the airblast atomizer were of a size range (mass median aerodynamic diameter [MMAD] < 1.6 microns) suitable for inhalation. Significant differences were observed for the grounded and electrostatically charged tower configurations, the latter producing the smaller median particle size at the expense of decreased collection efficiency. The electrostatically charged tower was size selective because of diffusion charging, retaining particles with an aerodynamic diameter (Dae) in the range 1 < Dae < 2 microns. The particle size was reduced with decreasing ambient relative humidity, although a controlled study of this parameter would be required to explicitly define its effects.

Nebulizers and Vaporizers↗
PubMed1994

Feasibility study on spray-drying protein pharmaceuticals: recombinant human growth hormone and tissue-type plasminogen activator.

The feasibility of spray-drying solutions of recombinant methionyl human growth hormone (hGH) and tissue-type plasminogen activator (t-PA) was investigated. hGH was formulated in a mannitol phosphate buffer and t-PA was used in an arginine phosphate formulation containing 0.004% (w/v) polysorbate 80. Using filtered air (90-150 degrees C) as the drying medium, hGH could be dried to a residual moisture content of < or = 4%. However, approximately 25% of the protein was degraded during the processing. Results of atomization studies suggest that surface denaturation at the air-liquid interface of the droplets in the spray plays a major role in the degradation of the protein. The addition of 0.1% (w/v) polysorbate 20 into the hGH formulation reduced the formation of soluble and insoluble aggregates by approximately 90% during atomization. During spray-drying the addition of 0.1% (w/v) polysorbate 20 reduced the formation of soluble and insoluble aggregates by approximately 70 and 85%, respectively. In contrast, t-PA remained intact upon atomization. Depending on the spray-drying conditions, product powders with a residual moisture content between 5 and 8% were obtained. No oxidation, aggregation, or denaturation occurred in the protein under several operation conditions. Overall, this study demonstrates that it is feasible to spray-dry t-PA in the current marketed formulation.

Calorimetry, Differential Scanning↗
PubMed2000

Triboelectrification of spray-dried lactose prepared from different feedstock concentrations.

Powder systems may acquire electrostatic charge during various pharmaceutical processing operations and may give rise to difficulties in handling and powder flow, mainly due to adhesion/cohesion effects. We have investigated the electrostatic charging of spray-dried lactose prepared from different feedstock concentrations using a laboratory spray-dryer. Triboelectrification of the spray-dried lactose samples was effected through contact with the stainless steel surface of either a mixing vessel or a cyclone separator. Results from both techniques showed differences in charge accumulation and particle-steel adhesion between the spray-dried lactose samples. As the feedstock concentration used to produce the spray-dried lactose was increased in the range 10-50% w/v, the mean charge on the lactose decreased from -20.8 to -1.3 nC g(-1) and -54.9 to -4.1 nC g(-1) for the mixing vessel and cyclone separator, respectively, with a corresponding decrease in adhesion. In addition, as the feedstock concentration was increased from 10 to 50% w/v, decreases were obtained in surface area values (1.06 to 0.56 m2 g(-1)), pore diameter (198.7 to 83.5 microm) and pore volume (1.09 to 0.75 cm3 g(-1)), and together with differences in crystal form correlated with the charge and adhesion results. The results suggested that the feedstock concentration could have a considerable influence on the charging and adhesional properties of spray-dried lactose. This may have relevance during pharmaceutical processing and manufacturing operations.

Animal Feed↗
PubMed2007

An atomic force microscopy approach for assessment of particle density applied to single spray-dried carbohydrate particles.

To evaluate an atomic force microscopy (AFM) approach for effective density analysis of single spray dried carbohydrate particles in order to investigate the internal structure of the particles. In addition, the AFM method was compared to an established technique, that is gas pycnometry. Resonant frequency AFM analysis was employed for determination of the mass of individual particles of spray-dried lactose, mannitol, and a mixture of sucrose/dextran (4:1). The effective particle density was calculated using the diameter of the spherical particles obtained from light microscopy. The apparent particle density was further analyzed with gas pycnometry. It was observed by microscopy that particles appeared either "solid" or "hollow." A solid appearance applied to an effective particle density close to the true density of the material, whereas a density around 1 g/cm(3) corresponded to a hollow appearance. However, carbohydrates, which crystallized during spray drying, for example, mannitol appeared solid but the average effective particle density was 0.95 g/cm(3), indicating a continuous but porous structure. AFM measurements of effective particle density corroborate the suggestion of differences in particle structure caused by the varying propensity of carbohydrates to crystallize during spray drying, resulting in mainly either amorphous hollow or crystalline porous particles.

Carbohydrates↗
PubMed2000

Surface composition of spray-dried particles of bovine serum albumin/trehalose/surfactant.

PURPOSE: To characterize via electron spectroscopy for chemical analysis (ESCA) the surface of spray-dried particles of trehalose plus a protein (bovine serum albumin). Additionally, to show how and why the addition of a surfactant reduces protein adsorption, and by this mechanism could reduce protein instability during spray-drying. METHODS: Aqueous solutions of trehalose plus bovine serum albumin (bSA) were spray-dried with increasing concentrations of surfactant. The surface composition of the dried particles was examined using ESCA. RESULTS: The presence of bSA, trehalose, and surfactant could be detected quantitatively in the particle surface. In the absence of surfactant the bSA had a large surface excess concentration (determined via its N atoms). Increasing concentration of polysorbate 80 reduced the surface excess of bSA in a concentration-dependent manner. At high polysorbate 80 concentration (5 mg/ml) the bSA could no longer be detected in solid surface. Using sodium dodecyl sulfate it was shown that the reduction in surface concentration of the protein is accompanied by a simultaneous increase in surface concentration of the surfactant. Neither surfactant fully covers the surface at the point of complete protein exclusion. CONCLUSIONS: ESCA provides a direct, quantitative measure of the surface composition of spray-dried trehalose/protein/surfactant particles. Surfactant reduces protein adsorption at the water/air-interface. This appears to be a result of complex formation with the surfactant within the bulk spray solution.

Animals↗
PubMed2003

Evaluation of the mucosal irritation potency of co-spray dried Amioca/poly(acrylic acid) and Amioca/Carbopol 974P mixtures.

The purpose of this study was to evaluate the biocompatibility of different Amioca/poly(acrylic acid) and Amioca/Carbopol 974P co-spray dried mixtures with an alternative mucosal irritation test using slugs. The irritation potential of the mixtures was measured by the amount of mucus produced during a repeated 30-min contact period. Additionally, membrane damage was assessed by measuring the protein and enzyme release from the body wall of slugs after treatment. All the Amioca/poly(acrylic acid) co-spray dried mixtures (50:50 and 25:75 ratios) induced slight irritation of the mucosal tissue as was demonstrated by the significantly increased mucus production however no increased protein and enzyme release was detected. Co-spray dried Amioca/Carbopol 974P mixtures containing 40% and more Carbopol 974P demonstrated a significantly higher mucus production and release of cytosolic LDH, indicating membrane damage. The total mucus production of the slugs treated with the co-spray dried mixtures containing up to 20% Carbopol 974P was significantly higher compared to the blank slugs. However, these mixtures induced no membrane damage since no additional effect on the protein release and no enzyme release was detected. By co-spray drying up to 20% Carbopol 974P could be incorporated without showing a distinct sign of irritation. These mixtures can be considered as potentially safe bioadhesive carriers.

Acrylates↗
PubMed1982

[On the polymorphism of barbiturates in powders and tablets. 6: Properties and behaviour of a spray-dried barbital preparation].

The manufacture of a spray-dried barbital preparation is described, the properties, tabletting behaviour and release of which were studied in comparison to the initial substance. Spray-drying led to a compression-resistant mixture of amorphous and crystalline particles. As most of these particles have a spherical shape, the tablets obtained from this mixture were of great compactness, which inhibited the penetration of the medium and, consequently, delayed the release of the drug, too.

Barbital↗
PubMed1999

Moisture effects on protein-excipient interactions in spray-dried powders. Nature of destabilizing effects of sucrose.

The preparation of stable solid protein formulations presents significant challenges. Ultimately, the interactions between incorporated excipients and the pharmaceutical protein determine the formulation stability. In this study, moisture was utilized to probe the interactions between a model protein, trypsinogen, and sucrose in the solid state, following spray drying. Through investigation of the physical properties of the spray-dried formulations, we attempted to elucidate the mechanisms underlying the previously observed stabilizing and destabilizing effects of the carbohydrate during spray drying. Both dynamic and equilibrium moisture uptake studies indicated the presence of an optimal protein-sugar hydrogen bonding network. At low sucrose contents, a preferential protein-sucrose hydrogen bonding interaction was dominant, resulting in protein stabilization. However, at high carbohydrate concentrations, preferential sugar-sugar interactions prevailed, resulting in a phase separation within the formulation matrix. The preferential incorporation of the sucrose molecules in a sugar-rich phase reduced the actual amount of the carbohydrate available to interact with the protein and thereby decreased the number of effective protein-sucrose contacts. As a consequence, the protein could not be effectively protected during spray drying. We hypothesize that the observed phase separation at this sucrose concentration regime originates from its exclusion from the protein in solution before spray drying, further accompanied by preferential clustering of the sucrose molecules.

Calorimetry, Differential Scanning↗
PubMed2003

Gelatin microparticles containing propolis obtained by spray-drying technique: preparation and characterization.

Gelatin microparticles containing propolis extractive solution (PES) were prepared by spray-drying technique. The optimization of the spray-drying operating conditions and the proportions of gelatin and mannitol were investigated. Regular particle morphology was obtained when mannitol was used, whereas mannitol absence produced a substantial number of coalesced and agglomerated microparticles. Microparticles had a mean diameter of 2.70 microm without mannitol and 2.50 microm with mannitol. The entrapment efficiency for propolis of the microparticles was upto 41% without mannitol and 39% with mannitol. The microencapsulation by spray-drying technique maintained the activity of propolis against Staphylococcus aureus. These gelatin microparticles containing propolis would be useful for developing intermediary or eventual propolis dosage form without the PES' strong and unpleasant taste, aromatic odour, and presence of ethanol.

Chromatography, High Pressure Liquid↗
PubMed2000

Preparation and characterization of spray-dried polymeric nanocapsules.

Recently, much interest has been generated by colloidal drug delivery systems such as nanocapsules because of the possibilities for controlled release, increased drug efficacy, and reduced toxicity after parenteral administration. Nanocapsules of poly-epsilon-caprolactone and Eudragit S90 were prepared. However, these systems present physicochemical instability. To dry these nanocapsule suspensions with the view of obtaining a solid form, the spray-drying process was used. Spray-dried powders of nanocapsules of poly-sigma-caprolactone and Eudragit S90 were prepared by atomization in a Büchi 190 Mini-spray dryer using colloidal silicon dioxide as a technological carrier. The morphological analysis of the surface at the powders showed that nanocapsules remain intact, and no change in particle size was detected after the spray-drying process. These results suggest that this method can be an interesting alternative to dry nanocapsule suspensions.

Chemistry, Pharmaceutical↗
PubMed2002

The effect of process variables on the degradation and physical properties of spray dried insulin intended for inhalation.

The aim of this study was to investigate the effect of process variables on the degradation and physical properties of spray dried insulin intended for inhalation. A 2(4) full factorial experimentally designed study was performed to investigate the influence of the following independent spray drying variables: feed flow rate, nozzle gas flow rate, inlet air temperature and aspirator capacity (drying gas flow rate). Human insulin (biosynthetic and Ph.Eur. quality) was dissolved in distilled water to concentrations of 5 mg/ml. The solutions were spray dried in a Mini Spray Dryer Büchi and the dry powders produced were characterized by high performance liquid chromatography, size exclusion chromatography, laser diffraction, thermo gravimetric analysis, scanning electron microscopy and weighing. The degradation of insulin was found to be affected mainly by the process variables that determine the outlet air temperature, i.e.: inlet air temperature, aspirator capacity and feed flow rate. The outlet air temperature should be kept below 120 degrees C to avoid degradation. A statistical optimization of the spray drying variables was performed, and found to recommend an experiment with an outlet air temperature of 61+/-4 degrees C. This experiment ought to generate a yield of 54+/-7% by weight of particles with a mass median diameter 2.9+/-0.4 microm, moisture content 3.9+/-0.5% by weight, content of high molecular weight proteins 0.3+/-0.1% by area, A-21 desamido insulin 0.3+/-0.05% by area and other insulin related compounds 0.3+/-0.1% by area.

Administration, Inhalation↗
PubMed1983

Direct preparation of solid particulates of aminopyrine-barbital complex (pyrabital) from droplets by a spray-drying technique.

Aqueous slurries of aminopyrine and barbital (molecular ratio 2:1) containing various excipients such as colloidal silica, synthetic aluminum silicate, montmorillonite clay, corn starch, microcrystalline cellulose, hydroxypropylcellulose, methylcellulose, gelatin, and chitosan were spray-dried by a centrifugal wheel atomizer with various rotation speeds (10,000-40,000 rpm) at various temperatures (85-145 +/- 5 degrees). The spray-dried products were a mixture of aminopyrine-barbital complex (molecular ratio 1:1), aminopyrine, and the excipient used. The flowability and the packing property of the products were improved by compounding colloidal silica into the formulation used for spray-drying. The products with montmorillonite clay, chitosan, and a corn starch-colloidal silica mixture were compressed directly into tablets. It was found that aminopyrine in the products was oxidized during spray-drying. The oxidation products were assumed to be a trace mixture of 5-oxo-2-methyl-4-dimethylamino-1-phenyl-3-pyrazoline carboxyaldehyde and miscellaneous oxidation products. Montmorillonite clay compounded in the formulation considerably prevented the oxidation of aminopyrine during spray-drying. The present study proposes an improved method for the preparation of solid particulates of aminopyrine-barbital complex for tableting, which combines the synthesis, drying, and agglomeration processes into a single process.

Aerosols↗
PubMed2002

Sustained release of etanidazole from spray dried microspheres prepared by non-halogenated solvents.

Etanidazole, a kind of radiosensitizer, was encapsulated in the spray-dried microspheres using biodegradable polymer PLGA 65:35 as the carrier for controlled release applications. Two non-halogenated solvents, e.g., ethyl acetate (EA) and ethanol, were tested to modify the properties of microspheres prepared by the commonly used solvent dichloromethane (DCM) alone. Their effects on the release behavior, morphology, particle size, and encapsulation efficiency of etanidazole-loaded microspheres were determined, and results were compared with DCM. The particle formation process via spray drying technique was also analyzed in order to understand the results obtained. It was found that larger percentage of EA (in the solvent mixture consisting of DCM and EA) in the fabrication of PLGA 65:35 microspheres decreases the initial burst, release rate and prolongs the release duration of etanidazole. In contrast to the spherical and porous microspheres prepared by DCM, the microspheres prepared by the solvent EA are all nonporous with a doughnut like surface structure due to its comparatively rapid phase transition (phase inversion) but slow solvent evaporation rate (longer time required to solidify). Increasing the polymer concentration (e.g., 4%, w/v) can bring about much more spherical microspheres by spray drying. Although ethanol, as a co-solvent, can dissolve a higher amount of etanidazole and lead to a higher drug encapsulation efficiency, the addition of ethanol in the DCM solvent can significantly increase the initial burst and the release rate of the microspheres due to the inhomogeneous drug distribution and structure of microspheres caused by phase separation. This study shows that ethyl acetate is an excellent low-toxic solvent that can be used in the spray drying technique for decreasing the initial burst, prolonging the release duration of a highly water-soluble drug like etanidazole. The use of EA provides a promising way to develop a sustained release system for etanidazole and other highly water-soluble drugs.

Acetates↗
PubMed1999

Spray-drying of trypsin - surface characterisation and activity preservation.

In the present study trypsin mixed with various carbohydrates, i.e. lactose, sucrose, mannitol, alpha-cyclodextrin and dextrin, was spray-dried in order to investigate the effects of spray-drying on this enzyme, with particular emphasis on the effects of interactions between trypsin and the surface formed during spray-drying. The protein was strongly over-represented at the surface of the powder particles, the surface coverage ranging from 10 to 65%, depending on the amount of trypsin in the solids (0.2-5%). This indicates that the protein adsorbs at the air/liquid interface of the spray-droplets, and that this surface is also largely preserved after drying. The surface concentration of protein in the spray-dried powders could be controlled by adding a surfactant to the mixture before drying, since the surfactant adsorbs preferentially at the air/liquid interface of the spray droplets, thus expelling protein from the surface. In general, the residual activity of trypsin in these non-optimised formulations was 90% or higher, and in no case less than 82%. It was found that the loss of activity could partly be explained by inactivation of the protein adsorbed at the surface. For mannitol and sucrose, however, the level of inactivation was higher than could be explained by surface inactivation alone, and additional mechanisms must also be considered.

Aerosols↗
PubMed1980

Biotin deficiency in mink fed spray-dried eggs.

Young standard dark mink developed classical symptoms of biotin deficiency, including underfur-greying, "spectacle eye," loss of fur, exudates from eyes, nose and mouth and encrustation of paws, when fed a diet containing 10% commercially produced, denatured spray-dried eggs. Comparable animals fed 5% spray-dried eggs did not show these symptoms; however, their pelts tended to be browner (i.e., lighter colored), than those of control animals. The feeding period during which these symptoms developed covered about 4 1/2 months: August 1 to December 13. Supplemental biotin (1.34 and .45 mg d-biotin per kilogram dry feed) prevented deficiency symptoms in mink fed 10% spray-dried egg of 20% fresh frozen whole chicken eggs, respectively. Eye exudates were most severe in October, when the combined stress of body and fur growth was greatest, then showed a partial remission as peak growth of body tissue and fur was passed. It was concluded that spray-dried eggs are insufficiently heat-treated to render their avidin content inactive; thus they should be appropriately supplemented with biotin for use in mink diets.

Animal Nutritional Physiological Phenomena↗
PubMed2000

Antiulcer effectiveness of Maytenus aquifolium spray dried extract.

The antiulcer activity of Maytenus aquifolium spray dried extract was studied in rats. Ulcers were induced by means of three experimental models: acidified-ethanol, indomethacin and acute stress. The extract was found to have significant antiulcer activity against all the models studied. These results show that preparation of the extract by means of the spray dried technique does not alter the biological activity of Maytenus aquifolium.

Animals↗