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At least 19 recordsLinked to original sources
PubMed1992

Microparticles of polyvinyl alcohol for nasal delivery. I. Generation by spray-drying and spray-desolvation.

Spray-drying and spray-desolvation are described for the generation of polyvinyl alcohol microparticles intended for nasal administration. The spray-dried microparticles of polyvinyl alcohol were of an appropriate size distribution but consisted of hollow spheres, which made them unsuitable for nasal delivery, as rapid clearance and a varied deposition pattern would be expected. Microparticles were also produced by spraying polyvinyl alcohol (average molecular weight of 14,000) solution (12.5%, w/v) at 0.332 ml/min onto the surface of acetone (spray-desolvation). These microparticles were solid collapsed spheres with the desired size for nasal deposition (10-200 microns). This method can be applied to encapsulation of drugs that are heat labile such as peptides and proteins.

Administration, Intranasal↗
PubMed1975

Improvement of solubility and dissolution rate of poorly water-soluble salicylic acid by a spray-drying technique.

Spray drying techniques have been applied to improve the solubility and dissolution rate of poorly water-soluble salicylic acid. Spray drying of the acid dispersed in acacia solutions resulted in as much as a 50% improvement in the solubility of the product. Solubility improvement was closely related not only to the concentration of acacia but also the amount of amorphous material in the spray-dried products. The heat of solution was inversely related to these parameters. The dissolution rate of spray-dried product was almost instantaneous being about 60 times faster than that of the original powder. A great improvement in the wettability of the spray-dried material seemed to be mainly responsible for the increase of dissolution rate.

Diffusion↗
PubMed1989

Protective effect of sucrose on spray drying of oxyhemoglobin.

As far as we know, spray drying has previously not been applied to oxyhemoglobin, undoubtedly because of the sensitivity of oxyhemoglobin to temperature and oxidation. Our experience with freeze drying encouraged us to perform spray-drying trials in order to compare the results of the two methods, in the absence and the presence of protective compounds. Spray drying of hemoglobin without a protective compound led, as in freeze drying, to formation of a percentage of methemoglobin (50%) that makes it unsuitable for transporting oxygen. In the presence of 0.25 M sucrose (optimum) and at 80-100 degrees C, the functional properties of the hemoglobin were well preserved (methemoglobin approximately 4%), and the residual humidity was limited to approximately 3%. Structural investigation by optical circular dichroism confirmed the results obtained by freeze drying: in the presence of an effective protector, the spectra were similar to those of control hemoglobin and the immediate environment of the heme did not undergo any major change. Electron spin resonance absorption bands in all samples were similar for each value of the spectral decomposition factor, g. This suggests that the structure of the heme is not altered by desiccation and that the protector does not penetrate into the heme pocket since it would have disturbed the symmetry of the crystalline field. Fundamentally, these results are equivalent or similar to those observed with freeze drying; since spray drying is a different process of dehydration, the results indicate a lack of specificity in the phenomena of oxidation or of protection affecting hemoglobin.

Chemistry, Pharmaceutical↗
PubMed1991

Optimization of spray-dried and -congealed lipid micropellets and characterization of their surface morphology by scanning electron microscopy.

Lipid micropellets prepared from glycerides and phospholipids may be a physiological drug carrier system for improving the intestinal absorption of lipophilic drugs. They can be prepared by spray-drying and spray-congealing processes. In this study, formulation and optimization parameters of spray-dried and -congealed lipid pellets in the micro- and nanometer size were investigated. The rapid evaporation of solvents from the droplets, which in turn causes a rapid solidification, influenced the crystalline structures of spray-dried glycerides. Moreover, solvents, the chain length, and the type of lipids and drugs used in the formulations of spray-dried micropellets affected the surface morphology of the micropellets. In contrast to the variations of the surface structure of spray-dried micropellets, formulated spray-congealed micropellets possessed smooth surface properties. The surface morphology and microstructure of both types of micropellets were characterized by SEM.

Chemistry, Pharmaceutical↗
PubMed1991

Tablet formulation study of spray-dried sodium diclofenac enteric-coated microcapsules.

Sodium diclofenac enteric-coated microcapsules were prepared by a spray-drying technique with Eudragit L 30D as enteric-coating material. The spray-dried powder, mixed with neocel or flo-starch, or the mixture of neocel and flo-starch (weight ratio, 1:1) was directly compressed into a tablet. The micromeritic properties of the spray-dried powder and the mixed powder for tableting were investigated. The flowability of the spray-dried powder was poor but improved after incorporating the excipients. The release rates of sodium diclofenac from the spray-dried powder, the mixed powder before tableting, and the tablets were determined in 0.1 N HCl solution, pH 6.8, phosphate buffer solution, distilled water, and pH-changed medium. The results indicated that the spray-dried powder, the mixed powder before tableting, and the tablets all exhibited enteric-coated release properties; these powders and tablets showed some resistance to stimulated gastric acid and then released drug more rapidly in pH 6.8 buffer solution. The weight ratio of neocel to flo-starch plays an important role in controlling the release of sodium diclofenac from enteric tablets. The 1:1 weight ratio of neocel to flo-starch was more suitable for designing the microdispersed sodium diclofenac enteric-coated tablets.

Acrylates↗
PubMed1988

Preparation of biodegradable poly(+/-)lactide microparticles using a spray-drying technique.

Drug containing biodegradable poly(+/-)lactide microparticles were prepared by using a spray-drying technique. Formulations containing model drugs in either a dissolved (progesterone) or dispersed state (theophylline) were spray-dried. The spray-drying method was less dependent on the solubility characteristics of the drug when compared with traditional microencapsulation techniques such as phase separation or solvent evaporation techniques. Differential scanning calorimetry and scanning electron microscopy were used to characterize the microparticles. The drug release profiles were characterized by a rapid release phase (burst effect) followed by a slow release phase, the extent of each phase being dependent on the drug loading.

Biodegradation, Environmental↗
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↗
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↗
PubMedDate not supplied

Plasticizers and their effects on microencapsulation process by spray-drying in an aqueous system.

Microencapsulated theophylline particles were prepared by an aqueous spray-drying process using hydroxypropylmethylcellulose. The effect of different plasticizers, triethylcitrate, polyethylene glycol, propylene glycol, glycerin and citric acid, was investigated. Triethylcitrate, a water-insoluble plasticizer, produced a porous honeycomb-like microcapsule wall resulting in rapid drug release. The presence of the plasticizers also influenced crystallization of the drug. The formation of a solid drug dispersion was observed with the addition of citric acid or glycerin. Changes in the pH of liquid feed caused by the plasticizer had an effect on the product dissolution profile, but this was not a major factor. Formation of pores due to leaching of plasticizers during dissolution enhanced drug release. Flow property measurements indicated that the plasticizers also affect the cohesiveness of the spray-dried products. Compared to the microcapsules formed without any plasticizers, propylene glycol, glycerin and citric acid appeared to be beneficial to the microcapsule wall formation, with microcapsules containing citric acid having the slowest drug release.

Crystallization↗
PubMedDate not supplied

Microencapsulation of menadione sodium bisulphite with polydimethylsiloxane by the spray-drying process: characterization by thermal analysis.

Menadione sodium bisulphite was microencapsulated with a polydimethylsiloxane membrane using spray-drying technology. Tests were performed using laboratory equipment and a Niro Atomizer pilot plant to scale up the process. The products were characterized with differential thermal analysis (DTA) and chemical and physical methods. Many differences between raw material and microencapsulated powder result from DTA data. The thermal characterization confirms that the spray-drying microcoating could be used to protect powder from the oxidative actions of the atmosphere.

Chemistry, Pharmaceutical↗
PubMed1977

Nutritional availability of spray dried lard water protein.

Four growth trials were conducted with rats and chicks to investigate the nutritional value of Spray Dried Lard Water (SDLW--a by-product from the rendering process of animal lard) as a source of protein in a semipurified diet. Weanling rats lost weight when fed a diet containing 10% of SDLW as sole source of protein. Responses of rats to amino acid(s) supplementation indicated tryptophan as the first-limiting amino acid, then threonine, methionine and lysine. One-week-old chicks fed diets containing SDLW to provide 20% crude protein responded to dietary amino acid supplementation. The results suggested that the limiting amino acid sequence of spray dried lard water for chicks was methionine, tryptophan, threonine and lysine, respectively. Results from this study also showed that biological availability of the amino acids in SDLW protein was rather low.

Amino Acids↗
PubMed1989

Paracetamol release from spray-dried products prepared with acrylic resins.

Ethanolic solutions of various paracetamol (acetaminophen)/Eudragit E, S, and RS ratios were spray-dried to obtain solid particulates. The products were tableted and the dissolution test of the tablets in distilled water and test solution (pH 1.2 and 7.2) were evaluated. The quantities and types of polymer as well as the dissolution media influenced the drug release. Spray-drying technique provided by the different types of Eudragits was an effective method for prolonging the release rate of paracetamol.

Acetaminophen↗
PubMedDate not supplied

[Search of optimum survival conditions for lactic acid bacteria in powders obtained by spray drying of yoghurt].

The paper reports the results of two spray-drying tests carried out on yogurt as such or previously neutralized. The operating conditions of the drying operation were such that the temperature of the product didn't exceed 80 degrees C, and the residual moisture of the powder was about 10%, slightly higher than the B.E.T. monolayer value. The decrease of total counts was three and two decimal reductions respectively for the natural and neutralized product. This latter gave also much higher viability index as determined in a "fermenting activity" test. Also, the analyses, related to the quality of the protein fraction, strongly support the opportunity of neutralization before drying. In storage tests carried out during 8 months the survival data were higher at 5% relative humidity (corresponding to 7-8% humidity) and at 5 degrees C temperature. In all cases the better results were obtained from the powders of neutralized yogurt, even in comparison with a freeze-dried sample obtained from the natural product. The typical shape of the sorption isotherms of these products suggests that the optimum process as regard to microorganisms' survival consists in drying the neutralized product up to residual humidities of 8-10%, followed by storage, in humidity-proof containers, at temperatures of about 5 degrees C.

Dairy Products↗
PubMed1992

Amorphism and physicochemical stability of spray-dried frusemide.

The physicochemical properties of amorphous forms of frusemide, prepared by spray-drying at 50 or 150 degrees C, and their hygroscopic stability at temperatures of 25 and 40 degrees C, and at 0 and 75% relative humidity were investigated. The glass transition temperature of the amorphous form A was 44.2 degrees C as measured by differential scanning calorimetry, while that of the amorphous form B was 54.4 degrees C. The activation energies for glass transition and crystallization processes were calculated from the differential scanning calorimetry thermograms of amorphous forms A and B, respectively. Stability determined by X-ray diffraction at 0% relative humidity, 25 and 40 degrees C suggested that form B was more stable than form A. However, the stability of form A at 75% relative humidity and 25 and 40 degrees C was similar to that of form B.

Drug Stability↗
PubMed1979

[The use of spray drying in pharmacy (author's transl)].

Owing to the favourable physical conditions of the evaporation process, the technique of spray drying has been used for some time to obtain dried products from solutions, suspensions, emulsions and fluid extracts. In the pharmaceutical industry, it may be utilized as a -drying technique, -micronizing procedure, -procedure for the manufacture of polymorphic or amorphic forms of active substances, -technique for producing microcapsules and spray embeddings, -method for manufacturing direct-tablettable active substances. The technical development which ranges from spray dryers for laboratory experiments to industrial plants, and the continuous operation are favourable prerequisites for research and use on an ever greater scale.

Adjuvants, Pharmaceutic↗