Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “EMULSIONS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1996

Lipid emulsions of palmitoylrhizoxin: effects of particle size on blood dispositions of emulsion lipid and incorporated compound in rats.

Emulsion formulations of various particle sizes for the highly lipophilic antitumour agent, RS-1541 (13-O-palmitoylrhizoxin), were prepared using dioctanoyldecanoylglycerol (ODO) as lipids and polyoxyethylene-(60)-hydrogenated castor oil (HCO-60) as a surfactant. These emulsions were evaluated as injectable drug carriers and compared with a colloidal solution. Both in vitro and in vivo after i.v. administration, RS-1541 was distributed into lipoproteins from the colloidal solution. When applied as emulsions of various particle sizes (124-419 nm) in vitro, RS-1541 was retained and stabilized within the emulsions. In the in vivo study, however, retention of RS-1541 in the emulsions after i.v. injection depended on their size. The small-particle emulsions (94-112 nm) resulted in long retention, and the large-particle emulsions (415-474 nm) led to short retention. Lipolysis rates of emulsion particles by lipoprotein lipase also depended on their size, indicating rapid lipolysis for small-particle emulsions (133 nm). However, the lipolysis was not such an extensive one, showing 10-30% release of capric acid from ODO within 6 h. Blood dispositions of capric acids approximately paralleled those of RS-1541 after i.v. injection of various particle size emulsions (130-368 nm) to rats, although relatively rapid eliminations of capric acids compared with RS-1541 were observed for the small-particle size emulsions (130 nm). These results suggest that when injected as emulsion formulations, the highly lipophilic antitumour agent, RS-1541, has behaviour similar to that of the emulsion particles in the body, which is dependent on the size of the latter. Thus, by properly selecting the particle size, lipid emulsions consisting of ODO and HCO-60 are expected to be effective and useful DDS carriers for RS-1541.

Animals↗
PubMed2002

Influence of the emulsion components and preparation method on the laboratory-scale preparation of o/w emulsions containing different types of dispersed phases and/or emulsifiers.

Emulsification is a complex process, strongly influenced by emulsion composition as well as by preparation procedure, and the characterisation of emulsions with regard to their structure and stability can be carried out with many different methods. To evaluate the influences of emulsion composition and preparation procedure on the structure and properties, oil-in-water emulsions were prepared using the model dispersed phase dodecane and the surfactant Tween on the one hand and the real food components sunflower oil (dispersed phase) and casein (emulsifier) on the other hand. The emulsions were prepared in a small laboratory-scale with a turbo-mixer alone and in combination with ultrasonic treatment. The emulsion activity was measured by photometry, the emulsion stability was evaluated visually and the droplet size was determined by laser particle analysis. The results of the investigations made with the model substances agree only partly with those made with the real food substances. For the model emulsions strong correlation were found between the emulsion activity and the particle sizer data because of the high purity and the defined structure of the model substances. On the contrary, for the emulsions made with the real food components sunflower oil and sodium caseinate the correlation were much weaker. Therefore a proper characterisation of the structure and properties of food emulsions requires examinations with several methods which are independent from each other. Furthermore, for laboratory-scale emulsification the combination of turbo-mixer and ultrasonic treatment is suitable to obtain small droplets and a narrow droplet distribution also for very small emulsion volumes.

Emulsions↗
PubMed1992

In vitro release, pharmacokinetic and tissue distribution studies of doxorubicin hydrochloride (Adriamycin HCl) encapsulated in lipiodolized w/o emulsions and w/o/w multiple emulsions.

The lipiodolized w/o emulsion or w/o/w multiple emulsion containing Doxorubicin hydrochloride (1; Adriamycin HCl) with different emulsifiers was prepared to evaluate in vitro sustained-release behavior, pharmacokinetic and tissue distribution function in Sprague Dawley (SD) rats. The results of dissolution indicate that the release of 1 was significantly sustained for both emulsions when HCO-60 (polyoxyethylene (60) hydrogenated castor oil) was used as an emulsifier. The serum concentration of 1 was reduced and prolonged for both emulsions with the increase of HCO-60. The C(max) level was lowered and T(max) value was delayed after administration of w/o emulsions with higher HCO-60 concentration. The apparent terminal half-life for 1 released from some emulsions with higher concentration of HCO-60 was 3-folds higher than that of the 1 solution. The clearance of some w/o or w/o/w ADR emulsions also decreased with the increase of HCO-60. Not only the concentration of 1 in heart and kidney decreased significantly after the administration of w/o emulsions with the higher concentration of HCO-60, but also the hepatic concentration of 1 was higher and increased with HCO-60 concentration. The hepatic 1 level became lower after administration of w/o/w multiple emulsions with the increase of HCO-60; however, the concentration of 1 in heart, lung and spleen increased somewhat. The results indicate that lipiodol and HCO-60 seemed to play an important role in the prolongation and selective retention of w/o emulsion or w/o/w multiple emulsion, in vitro and in vivo.

Animals↗
PubMed1993

Novel affinity separations based on perfluorocarbon emulsions. Development of a perfluorocarbon emulsion reactor for continuous affinity separations and its application in the purification of human serum albumin from blood plasma.

Perfluorocarbon affinity emulsions are generated by the homogenisation of a perfluorocarbon oil with a polymeric fluorosurfactant previously derivatised with an affinity ligand and subsequently cross-linked in situ. This procedure gives rise to a novel liquid affinity adsorbent that can be used for continuous protein purification. Discrete emulsion droplets were found to be unstable when pumped for prolonged periods; however, when flocculated, the emulsion floccules with diameters of around 125 microns, were very stable and sedimented faster. A four-stage reactor unit (perfluorocarbon emulsion reactor for continuous affinity separations, PERCAS) was designed and constructed to carry out continuous separations, and exploited the unusual properties of the absorbent, i.e. liquid nature and high density. Each of the four stages of PERCAS consisted of a mixing tank, for contacting between emulsion phase and aqueous phase, adjacent to a settling tank for the subsequent separation of emulsion from the aqueous phase. Using PERCAS adsorption, washing, elution and re-equilibration of the emulsion could be carried out continuously with emulsion recycle. Using single-component adsorption of human serum albumin to a perfluorocarbon affinity emulsion derivatised with the triazine dye C.I. Reactive Blue 2, PERCAS was optimised with respect to flow-rates and input concentrations. The work was then extended to the continuous purification of essentially homogeneous human serum albumin from blood plasma.

Adsorption↗
PubMed1994

Evaluation of milk fat-globule membrane (MFGM) emulsion for oral administration: absorption of alpha-linolenic acid in rats and the effect of emulsion droplet size.

The performance of milk fat-globule membrane (MFGM) emulsion as an oral dosage form was evaluated in rats using [14C]alpha-linolenic acid as a lipophilic model solute. For emulsions prepared by homogenization alone, the area under the plasma concentration versus time curve (AUC) after oral administration tended to be larger for MFGM emulsion, 35.0 +/- 2.5 micrograms eq.h/ml (mean +/- S.E., n = 3), than for Tween 80 emulsion, 28.5 +/- 0.6 micrograms eq.h/ml at p < 0.1, though the peak plasma concentration (Cmax) and the time required to reach Cmax (Tmax) were not significantly different. The absorption in the intestinal loop was not significantly different between the two emulsions, either. Thus, MFGM emulsion, compared with Tween 80 emulsion, did not show an obvious advantage or enhancement in the oral and intestinal absorption of alpha-linolenic acid, except for a slight increase in AUC. However, MFGM could be a good alternative to a synthetic emulsifier for oral use, considering that it is of natural origin and may be safer. In addition, it was shown that the AUC, as well as the absorption in the intestinal loop, was decreased for a MFGM emulsion in which the droplet size was reduced by sonication, presumably because of the observed decrease in alpha-linolenic acid concentration in the water phase, which was assumed to be the result of an increased distribution of alpha-linolenic acid, due to its amphipathic nature, to the increased oil-water interface.

Administration, Oral↗
PubMedDate not supplied

The influence of charged lipids on the flocculation and coalescence of oil-in-water emulsions. I: Kinetic assessment of emulsion stability.

The influence of various negatively charged lipids on the stability of phospholipid stabilized oil-in-water emulsions in the presence of varying concentrations of calcium chloride was examined by a measurement of the changes in the turbidity of the emulsion over time. The data were described well by the following equation: (Ai - A) = (Ai - A0) exp(-kt) where Ai is the maximum spectrophotometric absorbance achieved in the system, A is the absorbance at time t, A0 is the absorbance at the start of the experiment and k is the flocculation or coalescence rate constant. Plots of k and Ai/A0 vs. concentration of Ca++ provided an indication of the rate and extent of emulsion flocculation/coalescence, respectively. The sodium salts of phosphatidic acid (SPA) and oleic acid (SO) increased the critical flocculation concentration of calcium while sodium phosphatidylinositol (SPI) and sodium phosphatidylserine (SPS) had no effect on the critical flocculation concentration compared to the control emulsion. The addition of all lipid salts increased the rate of flocculation compared to the control emulsion, however, emulsions containing SPI demonstrated the highest values of k. In contrast, emulsions containing SO coalesced to the largest extent, as indicated by large values of Ai/A0. Systems containing charged phosphatides regained some stability in higher concentrations of Ca++ while those containing oleate were comparatively more unstable up to 20 mM Ca++. Based upon the results of the present studies, it appears that phosphatidic acid is the most important fraction of the anionic phosphatides in stabilizing an emulsion in the presence of calcium ion.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug Stability↗
PubMed1999

Lipid oxidation in emulsions as affected by charge status of antioxidants and emulsion droplets.

The influence of charge status of both lipid emulsion droplets and phenolic antioxidants on lipid oxidation rates was evaluated using anionic sodium dodecyl sulfate (SDS) and nonionic polyoxyethylene 10 lauryl ether (Brij)-stabilized emulsion droplets and the structurally similar phenolic antioxidants gallamide, methyl gallate, and gallic acid. In nonionic, Brij-stabilized salmon oil emulsions at pH 7.0, gallyol derivatives (5 and 500 microM) inhibited lipid oxidation with methyl gallate > gallamide > gallic acid. In the Brij-stabilized salmon oil emulsions at pH 3.0, low concentrations of the galloyl derivatives were prooxidative or ineffective while high concentrations were antioxidative. In SDS-stabilized salmon oil emulsions, oxidation rates were faster and the galloyl derivatives were less effective compared to the Brij-stabilized emulsions. Differences in antioxidant activity were related to differences in the ability of the galloyl derivatives to partition into emulsion droplets and to increase the prooxidant activity of iron at low pH.

Animals↗
PubMed1978

Studies on the adjuvant effect of water-in-oil-in-water (w/o/w) emulsion of sesame oil. 1. Enhanced and persistent antibody formation by antigen incorporated into the water-in-oil-in-water emulsion.

Water-in-oil-in-water (w/o/w) emulsion developed in our laboratory is as effective as water-in-oil (w/o) emulsion of Freund's incomplete adjuvant (FIA) in the stimulation of antibody formation. The emulsion is prepared by redispersion of water-in-sesame oil emulsion of an antigen solution in phosphate buffered saline with emulsifier, Tween 80. The emulsion can be stored at 4 degrees C for at least 3 months without any evidence of change in the adjuvanticity and in the w/o/w state. Even a single injection of bovine serum albumin (BSA) in the w/o/w emulsion elicited a high antibody response in mice over the period of almost whole lifespan. 10 microgram BSA in w/o/w could stimulate antibody formation up to 2(12) in hemagglutination titer, while the same dose in free solution did not elicit any detectable antibody. The tissue reactions caused by the w/o/w emulsion at the injected site and in the regional lymph nodes were much less prominent than those by FIA.

Adjuvants, Immunologic↗
PubMed1989

Effects of single application of a moisturizer: evaporation of emulsion water, skin surface temperature, electrical conductance, electrical capacitance, and skin surface (emulsion) lipids.

Effects of single application of an oil in water emulsion were studied on the forearm skin of 12 healthy volunteers. Five different non-invasive methods were used. Values were followed for 360 min after application of the emulsion, with the contralateral forearm as untreated control. The evaporation of emulsion water from the skin surface immediately rose to high values, but within 15 min returned to the original level. A parallel initial increase in conductance was observed; however, this was followed by a slightly increased level throughout the 360 min study. Electrical capacitance was also slightly increased throughout the study. Skin surface lipids, dominated by emulsion lipids, were increased, with high values for at least 120 min, followed by a gradual decline toward normal. Single application of emulsion is characterized by an initial evaporation phase, with evaporation of emulsion water, which lasts less than 15 min, followed by a lipidization phase, which lasts at least 360 min, dominated by the oil-constituent of the emulsion undergoing epidermal absorption. During the lipidization phase, epidermal hydration parameters are slightly but consistently improved.

Aged↗
PubMed1999

Perflubron emulsion delays blood transfusions in orthopedic surgery. European Perflubron Emulsion Study Group.

BACKGROUND: Fluorocarbon emulsions have been proposed as temporary artificial oxygen carriers. The aim of the present study is to compare the effectiveness of perflubron emulsion with the effectiveness of autologous blood or colloid infusion for reversal of physiologic transfusion triggers. METHODS: A multinational, multicenter, randomized, controlled, single-blind, parallel group study was performed in 147 orthopedic patients. Patients underwent acute normovolemic hemodilution with colloid to a target hemoglobin of 9 g/dl with an inspiratory oxygen fraction (FIO2) of 0.40. Patients were then randomized into one of four treatment groups after having reached any of the protocol-defined transfusion triggers including tachycardia (heart rate > 125% of posthemodilution rate or > 110 bpm), hypotension (mean arterial pressure < 75% of posthemodilution level or < or = 60 mmHg), elevated cardiac output (> 150% of posthemodilution level) or decreased mixed venous oxygen partial pressure (PVO2; < 38 mmHg). Treatments in the four groups were 450 ml autologous blood harvested during acute normovolemic hemodilution given at FO2 = 0.40; 450 ml colloid at FIO2 = 1.0; 0.9 g/kg perflubron emulsion with colloid (total = 450 ml) at FIO2 = 1.0; and 1.8 g/kg perflubron emulsion with colloid (total = 450 ml) at FIO2 = 1.0. The primary endpoint was duration of transfusion-trigger reversal. A secondary end-point was percentage of transfusion-trigger reversal. RESULTS: Perflubron emulsion was well tolerated with no serious adverse event attributed to drug treatment. Duration of reversal was longest in the 1.8 g/kg perflubron group (median, 80 min; 95% confidence interval, 60-100 min; P = 0.014 vs. autologous blood, P < 0.001 vs. colloid) followed by the 0.9 g/kg perflubron group (median, 59 min; 95% confidence interval, 40-90 min), the autologous blood group (median, 55 min; 95% confidence interval, 30-70 min) and the colloid group (median, 30 min; 95% confidence interval, 27-60 min). Percentage of reversal was also highest in the 1.8 g/kg perflubron group (97%; P < 0.001 vs. autologous blood; P = 0.014 vs. colloid), followed by 0.9 g/kg perflubron (82%), colloid (76%), and autologous blood (60%). CONCLUSIONS: Perflubron emulsion (1.8 g/kg) combined with 100% oxygen ventilation is more effective than autologous blood or colloid infusion in reversing physiologic transfusion triggers.

Aged↗
PubMed1995

Growth of food-borne pathogenic bacteria in oil-in-water emulsions: II--Effect of emulsion structure on growth parameters and form of growth.

The growth rates and yields of Listeria monocytogenes and Yersinia enterocolitica were determined in liquid culture media, and in model oil-in-water emulsions that contained 30, 70 or 83% (v/v) hexadecane. In emulsions with a mean droplet size of 2 microns containing 83% (v/v) hexadecane, the growth of both organisms resulted in decreased yields. Additionally, in these emulsions adjusted to pH 5.0 or 4.4 the growth rate of L. monocytogenes was significantly less than in other model systems which had an aqueous phase of equivalent chemical composition. Microscopic examination of the 83% (v/v) emulsion showed that its microstructure immobilized the bacteria, which were constrained to grow as colonies. Bacteria behaved similarly in model emulsions of either hexadecane or sunflower oil. Manipulation of the droplet size distribution of the emulsions changed the form and rate of growth of bacteria within them.

Alkanes↗
PubMedDate not supplied

Effect of primary emulsions on microsphere size and protein-loading in the double emulsion process.

Incorporation of a protein drug in microspheres made of a hydrophobic polymer is commonly achieved via double liquid-liquid emulsification (w/o/w) or by dispersing a powdered protein in a polymer solution followed by liquid-liquid emulsification (s/o/w). This study focused on the effect of the first operating step in both processes on the size and protein-loading of the microspheres. Bovine serum albumin (BSA) was used as the model protein and poly(methyl methacrylate) (PMMA) was used as the model polymer. The w/o emulsion was characterized based on the degree of emulsion fineness which was controlled using rotor/stator homogenization. The s/o emulsion was characterized based on protein powder size and shape. Protein powders of different sizes and shapes were produced using different powder preparation methods. In both emulsification processes, the second operating step which produced the microspheres was conducted in either a continuously stirred tank reactor (CSTR) or a static mixer. The size of the microspheres thus prepared was found to increase with increasing size of the protein powder in the s/o/w system but increase with decreasing size of the liquid emulsion droplets in the w/o/w system. Empirical correlations can accurately predict the size of the microspheres if the size of w/o emulsion droplets and protein powder is 10 x less than the microsphere size. Protein loading in the microspheres decreased with respect to increases in w/o emulsion droplet size or in protein powder size. We propose that these phenomena are attributed to two mechanisms, fragmentation along the weak routes in the w/o/w system and particle redistribution as the result of terminal velocity in the s/o/w system. The role of protein powder shape was not significant until the protein powder size exceeded 5 microns. Irregular-shaped protein powders resulted in lower encapsulation efficiency than spherical-shaped protein powders.

Animals↗
PubMed1990

Effect of phospholipid emulsifiers on physicochemical properties of intravenous fat emulsions and/or drug carrier emulsions.

The physicochemical properties of soy bean oil emulsions stabilized with purified egg lecithins (phosphatides) of various concentrations have been examined. The zeta potential of the emulsion droplets and the mean particle size of oil droplets in 10% (w/w) o/w-type emulsion decreased with increasing emulsifier concentration and then levelled off at more than 1.2% (w/w). In rheological measurements, at the initial stage, the viscosity of 10% (w/w) o/w-type emulsion gradually increased with increasing purified egg lecithin concentration, at the next stage, a plateau was reached at about 1.0-1.4% (w/w), and at the final stage, the viscosity curve showed a dramatic increase. These results indicate that emulsions stabilized by purified egg lecithin at more than 1.2% (w/w) are likely to be sufficiently stable.

Drug Carriers↗
PubMed1996

Physical states of surface and core lipids in lipid emulsions and apolipoprotein binding to the emulsion surface.

Plasma triglyceride-rich lipoproteins vary in lipid composition during their metabolism. We investigated the effects of the lipid composition of emulsion particles, specifically those of cholesterol enrichment and core replacement (replacing core triglyceride with cholesteryl oleate), on the physical states of surface and core lipids. Steady-state and time-resolved fluorescence anisotropies were measured in lipid emulsions using 1,6-diphenylhexatriene to probe the core and 1,6-diphenylhexatriene analogues for the outer and inner hydrophobic portions of surface phospholipids. In the absence of cholesterol, core replacement had little effect on the surface rigidity, despite the large difference in core mobility. However, core replacement caused a marked increase in surface rigidity in the presence of cholesterol. Quenching experiments using the fluorescent cholesterol analogue, dehydroergosterol, indicated that core replacement allowed surface dehydroergosterol to redistribute from the inner to the outer regions in the emulsion surface. These results indicated that core replacement modulates the surface properties of the emulsion particles through the redistribution of cholesterol in the surface layers. Furthermore, core replacement significantly decreased the binding of apolipoprotein E to the emulsion surface, whereas the binding of apolipoprotein CII responded to the cholesterol enrichment. This binding behavior of exchangeable apolipoproteins may closely correlate with the location of surface cholesterol and the mobility of core lipids.

Apolipoproteins↗
PubMed1987

A metabolic comparison of a pure long-chain triglyceride lipid emulsion (LCT) and various medium-chain triglyceride (MCT)-LCT combination emulsions in dogs.

Two 20% lipid emulsions containing mixtures of long-(LCT) and medium-chain triglycerides (MCT) were compared with a 20% LCT lipid emulsion. Beagles were infused with emulsions containing either 100% LCT, 75% LCT-25% MCT, or 50% LCT-50% MCT. The emulsions were part of a total parenteral nutrition (TPN) regimen that included 10% dextrose and 5.5% amino acids. Basic nutritional parameters as well as elimination kinetics were monitored. Plasma linoleic acid, ketone, lactate, pyruvate, insulin, glucose, and carnitine were analyzed. The 75% LCT-25% MCT emulsion offers little advantage over 100% LCT as a metabolic substrate. The 50% LCT-50% MCT combination proved to be a potentially better caloric source due to rapid elimination kinetics, increased ketone production, lack of deposition, and no interference with linoleic acid metabolism.

Animals↗