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PubMed1982

[On the compression behaviour of spray-dried sulphathiazole (author's transl)].

The authors prepared a spray-dried sulphathiazole product consisting of hollow pellets, the drug being in the form of its metastable modification I (melting point, 200 degrees C). On the basis of force-time diagrams and of current parameters relative to the elasto-plastic deformability of substances intended for tabletting, the compression behaviour of the spraydried product was compared with that of sulphathiazole (modification I) tempered at 180 degrees C for 150 min. Scanning-electron-microscopic studies on tablet surfaces offered further insight into the compressibility of the spraydried product.

Chemical Phenomena↗
PubMed2000

Temperature-induced crystallization and compactibility of spray dried composite particles composed of amorphous lactose and various types of water-soluble polymer.

The purpose of this study was to investigate the temperature-induced crystallization and the compactibility of the composite particles containing amorphous lactose and various types of polymers. The composite particles were prepared by spray-drying an aqueous solution of lactose and various types of gel forming water-soluble polymers at various formulating ratios. The stabilizing effect of hydroxypropylcellulose (HPC) and polyvinyl pyrrolidone (PVP) on amorphous lactose in the composite particles was smaller than that of sodium alginate in comparing at the same formulating ratios. The difference in the stability of amorphous lactose in the composite particles was attributed to the difference in the glass transition temperature (Tg) of the composite particles caused by the polymers formulated. The tensile strength of compacted spray-dried composite particles containing the polymers was higher than commercial lactose for direct tabletting (DCL21). The tensile strength of the composite particles was increased with an increase in water content in the particles. The difference in compactibility of the composite particles containing the different amount of polymer and water could be explained by the difference in Tg of the particles.

Alginates↗
PubMed2000

Technological considerations related to the up-scaling of protein microencapsulation by spray-drying.

Research and development of therapeutics and vaccines based on biodegradable polymers are intensive and one of the most promising fields in controlled drug delivery. However, new applications necessitate successful technology transfer and industrial scale-ups. In an endeavour to produce clinical samples of a single-administration tetanus vaccine based on poly(lactide-co-glycolide) microspheres, we report on technological parameters that are of importance in the up-scaling of the spray-drying process. The results show that an up-scaling of the encapsulation of protein vaccines or drug by spray-drying is feasible, but that additives, the type of polymer solvent, the polymer concentration, the w/o ratio and the product collection method influence process and product quality.

Biocompatible Materials↗
PubMed2005

Spray drying for generation of a ternary amorphous system of celecoxib, PVP, and meglumine.

Generation of amorphous forms of a poorly soluble drug by solid dispersion techniques has been a subject of intensive research for decades. Apart from the stability of the dispersions, development of a suitable production technology is a major challenge to the successful commercialization of these products. Coprocessing of celecoxib (CEL), poly(vinyl pyrrolidone), and meglumine by spray drying resulted in an amorphous drug product that provided enhanced solubility and stability to an otherwise poorly soluble crystalline form of CEL. The spray-drying process parameters were optimized to provide an amorphous product with required characteristics. The product was stable for 3 months under the accelerated stability storage conditions. This technique can serve as a suitable means for generating a ready-to-formulate amorphous drug-additive(s) composite that can be directly filled into hard gelatin capsules.

Air Pressure↗
PubMed2003

Stability of beta-carotene in spray dried preparation of Rhodotorula glutinis mutant 32.

AIMS: To obtain beta-carotene-rich dry cell preparation from mutant 32 of Rhodotorula glutinis and determination of its pigment stability. METHODS AND RESULTS: The mutant 32 of R. glutinis was grown in a 14 l stirred tank fermenter. Cell mass was concentrated 10-fold by cross-flow microfiltration and then spray dried. Butylated hydroxy toluene (BHT) and d-tocopherol were used as protecting agents. A two-level, three-variable, factorial optimization was performed to achieve moisture-free, non-viable and beta-carotene-rich feed additive. CONCLUSIONS: The beta-carotene and cell mass in stirred tank fermenter were found to be 54 +/- 5 mg l-1 and 12.8 +/- 2 g l-1, respectively. In the presence of BHT, 97 +/- 3% (w/w) beta-carotene was recovered for all the inlet temperatures studied. The best beta-carotene and yeast powder recoveries were obtained at 160 degrees C, 11.6% (w/v) cell mass concentration and 1 g l-1 BHT. The pigments inside dried yeast powder were stable in dark and cold condition for at least 10 weeks. The purified beta-carotene got almost totally denatured, under similar conditions of storage, within 76 h. SIGNIFICANCE AND IMPACT OF THE STUDY: Spray dried and stable preparation of beta-carotene-rich yeast, R. glutinis can provide alternative source of beta-carotene for use in animal nutrition.

Animal Feed↗
PubMed2004

Fluconazole encapsulation in PLGA microspheres by spray-drying.

Fluconazole-loaded PLGA microspheres were prepared by the spray-drying process. The influence of some process parameters on the physical characteristics of the microspheres was evaluated. Neither type nor polymer concentration influenced significantly the mean diameter of the microspheres, their size distribution and encapsulation efficiency of the drug. However, the drug loading greatly affected their size and the physical state in which fluconazole can exist in the matrix of the carriers, and, thus, affected the release rate of the drug. Results obtained by differential thermal analysis and X-ray powder diffraction revealed that at low nominal drug loading, fluconazole was incorporated in an amorphous state or in a molecular dispersion in the matrix of the microspheres and at high nominal drug loading part of the drug was in a crystalline form. Release profiles of fluconazole from the microspheres displayed a biphasic shape. The duration and extent of each phase were affected mainly by polymer nature, drug loading and physical state in which fluconazole existed in the polymeric matrix.

Antifungal Agents↗
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↗
PubMedDate not supplied

Modulation of rifampicin release from spray-dried microspheres using combinations of poly-(DL-lactide).

Microspheres containing 20% w/w rifampicin (RIF) with smooth morphology have been readily prepared from combinations of low, R104 (Mw, 2000) and moderate, R202H (Mw, 9000), molecular weight poly(D,L-lactide) (PDLLA) as a means to modulate drug release from either polymer when used alone. These have been characterized with respect to their drug loading, granulometry, in vitro drug release and thermal behaviour. Particle size distributions were Gaussian, whereby mean microsphere diameter was found to increase from 2.11 to 2.98 microns as the proportion of more viscous R202H increased, whilst > 95% of particles were < 10 microns, irrespective of the polymer blend used. Use of a reduced inlet temperature for spray-drying gave uncharacteristically high production yields in the range of 55.8-80.7% for the process. Encapsulation efficiencies were quantitative with the weight proportion of drug co-dissolved (p < 0.05), yielding microspheres of high and predictable RIF loading. In vitro drug release revealed a dramatic shift in release profile between 40 and 60% R104. Closer examination in this range showed the predicted pattern of increased release rate as the fraction of more hydrophilic R104 increased. However, disproportionate differences were evident between 44 and 48% R104. From the apparent temperature dependent drug release, the criticality of matrix composition was attributed to the coincidence of matrix softening with the dissolution medium temperature and consequent hydration, which, at a finite composition, resulted in a controlled auto-hydration mechanism. Dramatic dependence of release rate with dissolution methodology was accountable to the fact that drug release was considerably quicker where microspheres remained suspended and individualized with the USP paddle method as opposed to aggregated with the shaking bath methodology. In conclusion, the utility of blending racemic PDLLA to modulate drug release and the convenience of spray-drying as a technique to produce microspheres of predictable character have been demonstrated. The temperature-dependent release exhibited may have application in the site-specific delivery of drugs where local increased biochemical activity promotes drug release in response to an increased pharmacological need.

Aerosols↗
PubMed1993

Properties of Bacillus cereus spores in reference materials prepared from artificially contaminated spray dried milk.

A reference material for Bacillus cereus was developed based on spray drying of milk artificially contaminated with B. cereus spores. Various properties of the B. cereus spores in the milk powder were determined. The stability of the materials was good with no detectable decrease in the contamination level during 1 1/2 years storage at -20 degrees C or 4 weeks at 22, 30 or 37 degrees C. The homogeneity of the material was found acceptable for use as a reference material. Heat treatments (10 min at 70 or 80 degrees C) and addition of lysozyme to the enumeration medium did not influence the number of spores counted. The germination of the spores depended on the type of medium in which the milk powder was reconstituted, and on the storage period of the material. The suitability of the material was confirmed in a collaborative study. From the results obtained it was concluded that the material developed meets the general requirements set for reference materials and can therefore be used for, among others, testing laboratory performance.

Animals↗
PubMed1999

Chitosan microspheres prepared by spray drying.

Non-crosslinked and crosslinked chitosan microspheres were prepared by a spray drying method. The microspheres so prepared had a good sphericity and a smooth but distorted surface morphology. They were positively charged. The particle size ranged from 2 to 10 micron. The size and seta potential of the particles were influenced by the crosslinking level. With decreasing amount of crosslinking agent (either glutaraldehyde or formaldehyde), both particle size and zeta potential were increased. Preparation conditions also had some influence on the particle size. DSC studies revealed that the H2 antagonist drug cimetidine, as well as famotidine was molecularly dispersed inside the microspheres, in the form of a solid solution. The release of model drugs (cimetidine, famotidine and nizatidine) from these microspheres was fast, and accompanied by a burst effect.

Biocompatible Materials↗
PubMed2004

Effect of water activity on the release characteristics and oxidative stability of D-limonene encapsulated by spray drying.

The stability of encapsulated D-limonene, which was prepared by spray drying, was studied in view of the release characteristics and oxidation stability. Gum arabic, soybean water-soluble polysaccharide, or modified starch, blended with maltodextrin were used as the wall materials. The powders were stored under the conditions of 23-96% relative humidity at 50 degrees C. The release rate and the oxidation rate were closely related to the relative humidity. The relationship was not simple. Initially, the release rate and the oxidation rate increased with increasing water activity, but around the glass transition temperature, the rates decreased sharply to increase again at a further increase of water activity. The results could be explained by a change in the powder structure, where a glass capsule matrix was changed into rubbery state during storage.

Capsules↗
PubMedDate not supplied

Rhizobacteria microencapsulation: properties of microparticles obtained by spray-drying.

Rhizobacteria Pseudomonas fluorescens-putida were microencapsulated in Eudragit by spray-drying. These microparticles are subsequently included in seed coating or pelleting material. The survival of the bacterial cell in microparticles were studied under different levels of relative humidity (RH): 0, 33, 55 and 100%. The protective effects of silica, present in certain formulations, were demonstrated at the relative humidities of 33 and 55%. The release of the encapsulated bacteria was also studied over time. The release was fast, the bacteria being observed at 15 min immersion of the Eudragit microparticles in an aqueous-buffer medium at 20 degrees C. This result, related to the physicochemical character of the coating polymer, showed that water was the triggering element for the release of rhizobacteria. Compatibility studies between two film-forming agents used for seed coatings and the encapsulated bacteria, as well as wettability measures of tableted microparticles, were carried out. The bacterial survival was good with the seed coating agent, Sepiret 1039G, and the wettability measurements of agglomerated microparticles were in accord with the rapid release of the microencapsulated bacteria. The application of microparticles containing rhizobacteria on seeds can now be considered for preliminary trials.

Acrylic Resins↗
PubMed2001

Optimization of spray drying by factorial design for production of hollow microspheres for ultrasound imaging.

A process for producing hollow microcapsules as ultrasound contrast agents was optimized using a 2(3) factorial experimental design method with two replicates. Spray drying, a conveniently scalable encapsulation technique, was used to encapsulate a volatile core material, such as ammonium carbonate, using biodegradable 50-50 poly(D,L-lactide-co-glycolide). Various effects due to changes in processing variables and their interactions were studied using the factorial grid. The high- and low-incremented variables examined included the temperature difference between the inlet and outlet of the spray dryer (5 degrees and 15 degrees C), air atomization pressure (80 and 100 psi), and polymer concentration in solvent (0.005 and 0.025 g/mL). Responses analyzed for computing the main effects and interactions were microcapsule morphology, yield, mean size, and zeta potential. Experimental results showed that polymer concentration was most important for determining microcapsule morphology. The temperature difference for drying prominently affected mean size, and atomization pressure was the main effect for microcapsule yield. Interactions among variables were not present in this case. The best conditions for producing PLGA microcapsules was a temperature difference of 5 degrees C, an initial polymer concentration of 0.005 g/mL, and an atomization pressure of 80 psi. The microcapsule zeta potentials were unaffected by spray-drying conditions.

Biocompatible Materials↗
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↗
PubMed2001

Receptor-mediated targeting of spray-dried lipid particles coformulated with immunoglobulin and loaded with a prototype vaccine.

PURPOSE: Spray-dried lipid-based microparticles (SDLM) serve as a platform for delivery of a wide variety of compounds including peptides, proteins, and vaccines to the respiratory mucosa. In the present study, we assessed the impact of IgG-mediated targeting to phagocytic cells of inactivated influenza virus formulated in SDLM, on subsequent immune responses. METHODS: SDLM were produced containing inactivated influenza virus strain A/WSN/32/H1N1 (WSN), with or without IgG. Using phagocytic antigen presenting cells (APC) and a T cell hybridoma (TcH) line specific for a dominant influenza virus epitope, we compared the in vitro responses elicited by ligand-formulated (SDLM-IgG-WSN) and non-ligand particles (SDLM-WSN). The effect of including the IgG ligand in the formulation was further characterized by measuring the immune responses of rodents vaccinated with SDLM. RESULTS: SDLM-IgG-WSN were internalized in an Fc receptor (FcR)-dependent manner by phagocytic APC that were then able to effectively present a dominant, class II-restricted epitope to specific T cells. While SDLM-WSN elicited a lower response than administration of plain inactivated virus in saline, the level of the T cell response was restored both in vitro and in vivo by incorporating the APC FcR ligand, IgG, in the SDLM. CONCLUSIONS: Incorporation of FcR ligand (IgG) in SDLM restored the limited ability of formulated virus to elicit T-cell immunity, by receptor-mediated targeting to phagocytes.

Administration, Inhalation↗
PubMed2002

Growth performance and health status in weanling piglets fed spray-dried porcine plasma under typical Northern European conditions.

The effect of inclusion of spray-dried porcine plasma (SDPP) in diets for weanling piglets was studied. The objectives were to determine whether SDPP would have positive effects on post-weaning piglet performance and health under typical Northern European conditions. In experiment 1, 160 weanling piglets were assigned randomly to a control diet or a diet containing 3% SDPP, which was added at the expense of both fishmeal and dried skim milk. In experiment 2, 264 weanling piglets were assigned to a control diet containing whey protein, a diet without whey protein but with SDPP or a diet containing both whey protein and SDPP. In essence, SDPP was added to the test diets at the expense of either whey protein or fishmeal. Piglets were fed the diets for 3 weeks. In experiment 1, the piglets fed the SDPP diet had a 7% higher average daily gain (ADG) and a 4% lower feed conversion ratio (FCR) (p < 0.05) during the first 3 weeks after weaning than did those fed the control diet. There were no differences in leucocyte counts or gamma-globulin. In experiment 2 there were no significant differences in ADG and FCR among the dietary treatments. It is concluded that low amounts of SDPP in weanling diets can have positive effects on growth performance under Northern European conditions.

Animal Feed↗
PubMed2002

Small intestinal morphology and disaccharidase activities in early-weaned piglets fed a diet containing spray-dried porcine plasma.

The purpose of this study was to test whether dietary spray-dried porcine plasma (SDPP) in early-weaned piglets prevents small intestinal villus atrophy by trophic or protective activity. Fifty-four weaned, 18-day-old piglets were used to determine the effect of dietary SDPP on small intestinal villus length, crypt depth, enterocyt mitotic activity and brush border enzyme activities during the first week after weaning. The piglets were offered a diet containing either 8% SDPP or 8% casein. At 2 and 7 days after weaning, piglets were anaesthetized to provide samples of the small intestinal wall and killed immediately afterwards. There were no differences in daily gain and daily feed intake between the two dietary treatments. At day 2 after weaning, all piglets showed a marked reduction in villus height when compared with baseline values. In all piglets, small intestinal enterocyte mitotic activity had decreased by day 2 and was increased again on day 7. There were no significant effects of dietary SDPP on small intestinal villus length, crypt depth and enterocyt mitotic activity. This indicates that SDPP has no trophic effect on the small intestinal mucosa and that it does not protect against the damaging effect on the small intestinal villi that is associated with the process of weaning. There was no effect of SDPP on lactase-, sucrase- or maltase-specific activities that are a measure of the digestive function of the small intestine. It can be concluded that SDPP versus casein has no effect on small intestinal morphology and disaccharidase activities in early weaned piglets kept under low infection pressure.

Animal Feed↗