Concentration Of Emulsifying Agent Research Articles

Investigation of the effects of some process variables on the Azithromycin Microencapsulation by the Quasi-Emulsion Solvent Evaporation Method

The aim of the present work was to identify the optimum formulation parameters required to achieve a maximum production yield and entrapment efficacy for Azithromycin-loaded Ethylcellulose microparticles for taste masking of Azithromycin (AZI). Quasi-emulsion solvent evaporation method was employed using Ethylcellulose. Several factors that influence the microparticles such as polymer-to-drug ratio, the inner phase volume (DCM), and the emulsifying agent concentration (PVA) were studied to determine their effects on the production yield, entrapment efficiency, and particle size of microparticle formulations. The formula F3 that provided the highest yield and entrapment efficiency (66.6±0.3%, 86.42±0.05% respectively) was evaluated using Scanning electron microscopy (SEM), Fourier transform infrared (FT‑IR), and Differential scanning calorimetry (DSC). Taste masking assessment performed in vitro. FT‑IR study showed that there was no interaction occurring between azithromycin and ethylcellulose. DSC confirmed the conversion of azithromycin from crystalline phase to amorphous phase and entrapped inside the microparticles. SEM micrographs revealed that microparticles were spherical in shape with a porous nature, where no drug crystals on the surface could be observed, indicating an encapsulation of AZI inside the polymeric matrix. In vitro, the taste assessment revealed no azithromycin release in salvia pH which could effectively mask the bitter taste of AZI.

Preparation, statistical optimization, in-vitro evaluation and characterization of solid lipid nanoparticles of an anti-retroviral drug Nevirapine

Nevirapine-loaded solid lipid Nanoparticles (SLNs) were manufactured using lipid and emulsifying agent by hot homogenization method. The goal of research was to formulating a SLN system to target the HIV reservoir which is mostly found in the lymphatic system and to conquer the obstacle of drug itself. Also, nearly 50% of antiviral drugs fall within BCS class 2, which have low solubility. 44% antiviral drugs belongs to BCS class 3 have inadequate permeability and 6% belongs to class 4 with inadequate solubility and inadequate permeability. Depending on the NVP solubility and stable formulation, stearic acid as a lipid and poloxamer 188 and tween 80 as an emulsifying agent were chosen and SLNs were manufactured with the help of hot homogenization method. Optimization of independent variables such as lipid concentration, emulsifying agent concentration and no. homogenization cycle was carried. The effect of independent variables on the dependent variables i.e. particle size and entrapment efficiency was studied. Optimized formulation which was lyophilized (L-SLN) and this L-SLN additionally characterized using DSC, SEM and XRD analysis. Also, in-vitro drug release of optimized batch studied in 0.04 M Sodium phosphate buffer pH 6.8 containing 2% SLS, demonstrated 41.83% release at the end of 24th hr. Absence of low intensity in XRD indicated the presence of amorphous SLNs. SEM showed the morphology of SLNs. No prominent changes observed in the accelerated stability studies.

Propolis emulgel: a natural remedy for burn and wound

Objectives: To develop an alternative medicine, propolis, in emulgel formulation for burn and wound treatment.Methods: The effect of two independent variables: emulsifying agent concentration and oil concentration on the cumulative amount of propolis release (dependent variable) from liquid paraffin and isopropyl palmitate emulgels was investigated. Eight formulations were prepared and evaluated for physical appearance, pH, propolis content, viscosity, and in vitro propolis release. The release results were fitted into different kinetic equations and analyzed using contour plot, interaction surface plot and one-way ANOVA. The selected emulgel formulation was investigated for its wound and burn healing activity in rats.Results: All the prepared emulgels showed acceptable physical properties concerning color, homogeneity, consistency, and pH value. The concentration of emulsifying agent had more pronounced effect on propolis release than oil concentration. Formulations F1–F6 showed “anomalous” drug release, while Formulations F7 and F8 showed zero-order kinetic.Conclusion: The formulation F7 with 5% isopropyl palmitate, 5% emulsifier mixture, 1% hydroxyl propyl methyl cellulose, 1% oleic acid, and 10% propylene glycol is a promising formula for better management of wound and burn.

Preparation and Evaluation of Physical and, Rheological Properties of Clotrimazole Emulgel

Recently, emulgel has emerged as one of the most interesting topical preparations in the field of pharmaceutics. In this research clotrimazole was formulated as topically applied emulgel ; different formulas were prepared. The prepared emulgels were evaluated for their physical appearance , rheological behaviour , and in vitro drug release . The influence of the type of gelling agent (carbopol 934 and methyl cellulose), the concentration of both the emulsifying agent (2% and 4% w/w of mixture of span 20 and tween 20) and the oil phase (5% and 7.5% w/w of liquid paraffin) and the type of oil phase (liquid paraffin and cetyl alcohol), on the drug release from the prepared emulgels was investigated. Commercially available topical canestin® cream was used for comparison. All the prepared emulgels showed acceptable physical properties concerning colour, homogeneity, consistency, and pH value. Rheological studies revealed that all emulgels formulations exhibited a shear – thinning behaviour with thixotropy, indicating structural break down of intermolecular interaction between polymeric chains. Clotrimazole emulgels exhibited higher drug release than canestin® cream. The results of in vitro release showed that methyl cellulose – based emulgel gave better release than carbopol 934 – based one. Also it was found that the emulsifying agent concentration had the most pronounced effect on the drug release from the emulgels, followed by the oil phase concentration, which has a retardation effect, and finally the type of the gelling agent. It was suggested that the clotrimazole emulgel formulation prepared with methyl cellulose, with low concentration of oil phase (5%w/w liquid paraffin) and high concentration of emulsifying agent (4%w/w), showed an optimum formula for highest drug release (74.4% after three hours), which followed higuchi diffusion model with a diffusion-controlled mechanism. 
 Key words: Emulgel , carbopol , methyl cellulose , clotrimazole 

Effect of Ultrasound on the Nominal Viscosity of Water –Asphalt Emulsions

The effects of ultrasound on the viscosity properties of water—asphalt emulsions stabilized by non-ionizable surfactants are studied. The viscosity properties of the emulsions depend on the emulsifying agent concentration and the emulsion ultrasonic treatment time. Competing processes of dispersion and coagulation of particles, which affect the ultimate properties of the emulsion, occur during the ultrasonic irradiation. This fact dictates the need for selecting the optimum ultrasonic irradiation time for ensuring that the asphalt emulsions are highly disperse and approach a monodisperse state.

Physical and chemical stabilities of β-carotene emulsions stabilized by Ulva fasciata polysaccharide

The objectives of this study were to investigate the effect of Ulva fasciata polysaccharide (UFP) on the physical and chemical characteristics of β-carotene oil-in-water (O/W) emulsions. The β-carotene (O/W) emulsions were prepared by combining 95 wt% UFP (1–5%, wt/wt) solutions with 5 wt% soybean oil containing β-carotene (0.05 wt% in the final emulsion). The stability of β-carotene emulsions was evaluated by droplet size and distribution, viscosity, zeta-potential, visual phase separation, light microscopy imaging and β-carotene degradation of the emulsions during storage. In addition, the influences of ionic strength and pH on physical stabilities of emulsions were characterized. Emulsions stabilized with high concentration (>2% wt/wt) of UFP had an average droplet size (D [3, 2]) less than 1.0 μm, and the average droplet size significantly decreased until the polysaccharide concentration reached 3%. Light microscopy images and emulsion zeta-potentials demonstrated 3% (wt/wt) UFP to be the optimum emulsifying agent concentration. UFP revealed better emulsifying properties and improved physical stabilities of β-carotene emulsions when compared to other commercial polysaccharides, including gum Arabic and beet pectin.

Freeze gelcasting of naphthalene-in-aqueous alumina slurry emulsions for the preparation of macroporous alumina ceramics

An emulsion freeze gelcasting process has been studied for the preparation of macroporous alumina ceramics. The naphthalene-in-aqueous alumina slurry emulsions prepared at 90°C from a 30vol% alumina slurry undergo gelation on cooling in a mould due to the solidification of naphthalene and physical cross-linking of the carrageenan present in the aqueous slurry. The medium internal phase emulsions with naphthalene to alumina slurry volume ratios in the range of 1 to 1.86 show shear thinning flow behavior with low viscosity and yield stress, suitable for casting. The room temperature drying of the gelled bodies followed by naphthalene removal at 70°C and sintering at 1550°C produces macroporous alumina ceramics with porosity in the range of 65 to 78%. The macropore morphology depends on the emulsifying agent (sodium dodecyl sulphate) concentration and naphthalene to alumina slurry volume ratio. The average macropore size (35.1 to 4.9μm) decreases with an increase in the emulsifying agent concentration and naphthalene to alumina slurry volume ratio. The macroporous ceramics obtained have high compressive (7 to 28.75MPa) strength and Young’s modulus (553 to 1230MPa).

Optimization of chlorphenesin emulgel formulation

This study was conducted to develop an emulgel formulation of chlorphenesin (CHL) using 2 types of gelling agents: hydroxypropylmethyl cellulose (HPMC) and Carbopol 934. The influence of the type of the gelling agent and the concentration of both the oil phase and emulsifying agent on the drug release from the prepared emulgels was investigated using a 2(3) factorial design. The prepared emulgels were evaluated for their physical appearance, rheological behavior, drug release, antifungal activity, and stability. Commercially available CHL topical powder was used for comparison. All the prepared emulgels showed acceptable physical properties concerning color, homogeneity, consistency, spreadability, and pH value. They also exhibited higher drug release and antifungal activity than the CHL powder. It was found that the emulsifying agent concentration had the most pronounced effect on the drug release from the emulgels followed by the oil phase concentration and finally the type of the gelling agent. The drug release from all the emulgels was found to follow diffusion-controlled mechanism. Rheological studies revealed that the CHL emulgels exhibited a shear-thinning behavior with thixotropy. Stability studies showed that the physical appearance, rheological properties, drug release, and antifungal activity in all the prepared emulgels remained unchanged upon storage for 3 months. As a general conclusion, it was suggested that the CHL emulgel formulation prepared with HPMC with the oil phase concentration in its low level and emulsifying agent concentration in its high level was the formula of choice since it showed the highest drug release and antifungal activity.

Biodegradable bromocryptine mesylate microspheres prepared by a solvent evaporation technique. I: Evaluation of formulation variables on microspheres characteristics for brain delivery

The aim of this study was to formulate biodegradable microspheres containing an anti-parkinsonian agent, bromocryptine mesylate, for brain delivery. The effect of formulation parameters (e.g. polymer, emulsifying agent type and concentration) on the characteristics of the microspheres produced, the efficiency of drug encapsulation, the particle size distribution and in vitro drug release rates from the bromocryptine mesylate microspheres were investigated using a 3 2 factorial design. Bromocryptine mesylate was encapsulated into biodegradable polymers using the following three different polymers; poly(L-lactide), poly(D,L-lactide) and poly(D,L-lactide-co-glycolide). The SEM photomicrographs showed that the morphology of the microspheres greatly depended on the polymer and emulsifying agent. The results indicate that, regardless of the polymer type, increase in emulsifying agent concentration from 0.25-0.75% w/v markedly decreases the particle size of the microspheres. Determination of particle size revealed that the use of 0.75% w/v of emulsifying agent concentration and a polymer solution concentration of 10% w/v resulted in optimum particle size. In order to prepare biodegradable microspheres with high drug content and small particle size, selection of polymer concentration as well as emulsifying agent concentration is critical. Polymer type has a less pronounced effect on the percentage encapsulation efficiency and particle size of microspheres than on the t 50% . The microspheres prepared by all three polymers, at a polymer concentration of 10% w/v and an emulsifying agent concentration of 0.75% w/v with NaCMC:SO (4:1, w/v) mixture was as the optimum formulation.

The effects of ethanol content and emulsifying agent concentration on the stability of vegetable oil‐ethanol emulsions

AbstractIn vegetable oil‐ethanol emulsions ethanol is the polar phase and vegetable oil is the nonpolar phase. The primary advantage of vegetable oil‐ethanol emulsions over conventional water‐oil emulsions is that they enable the incorporation of water‐and oil‐insoluble or poorly soluble functional compounds and/or drugs into emulsions. A number of nonionic surfactants were used to select appropriate stabilizers for stable vegetable oil‐ethanol emulsions. We found decaglycerol mono‐oleate (MO750) to be the best stabilizer for ethanol‐in‐oil (E/O) emulsions. The effects of ethanol content and of emulsifying agent concentration on the stability of vegetable oil‐ethanol emulsions were examined with MO750. After emulsification, two turbid layers formed simultaneously when ethanol content exceeded 20 wt%. The top layers (oil‐in‐ethanol emulsions; O/E emulsions) were very unstable, whereas the stability of the bottom layers (E/O emulsions) depended on the ethanol content. The stability of E/O emulsions is closely related to the effective concentration of MO750 aggregates, which play an important role in the film thickness stability of interfacial films formed by surfactant aggregates. Instability of E/O emulsion at 5 wt% MO750 is probably due to the polydispersity (i.e., nonuniform size and shape) of MO750 aggregates at high MO750 concentration. E/O emulsions prepared with 0.1, 0.5, and 1 wt% MO750 were stable, suggesting that the interfacial films formed were effective in protecting the droplets against coalescence and Ostwald ripening.

Effect of lecithins on BCG-alginate-PLL microcapsule particle size and stability upon storage

Alginate-PLL microcapsules containing BCG were prepared by emulsification/ internal gelation of an alginate solution dispersed within a vegetable oil containing lecithins as emulsifiers. The lecithins studied were soy bean lecithin at 0.1, 0.5, 1 and 2%concentration; and dried egg yolk lecithin at 0.1, 0.25, 0.5 and 1%. The microcapsule particle size showed a dependence upon the amount and type of lecithin added to the oil. Increasing the emulsifying agent concentration was found to reduce particle size, from 50.9mum obtained when lecithins were not used in the emulsification step, to 13.9mum obtained when 1% dried egg yolk lecithin was employed. The encapsulated BCG was identified by the Difco TB stain set K, followed by observation under optical microscopy. Once prepared, microcapsules were freeze-fried using 5%trehalose as cryoprotectant in order to preserve their stability upon storage. The stability of the microcapsules was assayed over 12 months at room temperature, finding that alginate-PLL microcapsules were stable up to 6 months. Moreover, in the case of microcapsules prepared with lecithins, a significant increase in particle size was observed, from 16.9mum at the beginning of the study to 25.2mum at 12 months storage.

Effects of preparation variables of enzyme-encapsulating water-in-oil emulsion on enzymatic reaction conversion and emulsion stability in an enzyme–emulsion–liquid–membrane reactor

The effects of various water-in-oil (W/O) emulsion preparation variables, such as water-to-oil volume ratio of W/O emulsion, emulsification speed and time, and emulsifying agent concentration, on the permeation rates of l-phenylalanine methyl ester ( l-PME, substrate) and l-phenylalanine ( l-Phe, product) were investigated in an enzyme–emulsion–liquid–membrane (EELM) system accompanying the hydrolysis of the substrate into the product. The permeation rate of the substrate was higher in the system with a higher water-to-oil volume ratio or lower emulsification energy, while emulsifying agent concentration had little influence on its permeation rate as far as emulsion was stable. The permeation rate of the product was highest in the system with water-to-oil ratio of 1/1, the lowest emulsification energy or 7 wt.% emulsifying agent concentration. This is because the rate was dependent only on the mass transfer resistance, such as surfactant layer resistance at interfaces, membrane thickness, and the mass transfer area between external phase and emulsion drops. The explanation was supported by the experimentally measured data of emulsion drop size, emulsion viscosity, and internal droplet size. Finally, the optimum permeation rate was obtained at 7 wt.% emulsifying agent concentration, water-to-oil volume ratio of 1/1 and emulsification speed of 6000 rpm for 15 min.

A study of the electrorheological effect of γ-Fe2O3/polyacrylate composite particles

γ-Fe2O3/polyacrylate composite particles were synthesized through inversed emulsion polymerization. The particles were then dispersed in silicone oil, forming the electrorheological fluid. The effects of the chemical constitution of the particles, including the content of γ-Fe2O3, the crosslinking agent N,N′-methylene-bis acryl-­amide (MBAM) and the comomoner maleic anhydride (MA) on the shear stress of the fluid were investigated under direct and alternating electrical fields respectively. The influence of the emulsifying agent concentration during the particle preparation on the electrorheological (ER) effect of the fluid was studied. The results show that the ER effects are different under direct and alternating electrical fields. The ER effects of the γ-Fe2O3/lithium polyacrylate particles at some γ -Fe2O3 contents are stronger than that of the lithium polyacrylate especially under alternating fields. The contents of the crosslinking agent MBAM, the comonomer MA and the emulsifying agent cetyltrimethyl ammonium bromide influence the ER effects and the morphology of the composite particles. Copyright © 1999 John Wiley & Sons, Ltd.

Flow Characteristics of Emulsion Fracturing Fluids.

Oil permeability measurements of 66 Saudi carbonate and sandstone formations were made and 25% of these data were ranged from 0.5 to 10 millidarcies. An emulsion of 70% Saudi crude oil (Safanyia-Khafji) and 30% polymer-gelled water was selected to fracture these formations. This paper shows the effect of emulsifying agent concentration on the pseudoplasticity nature of the emulsion fracturing fluid.Rheological properties of the oil/polymer-gelled water emulsions were analyzed using a Fann VG viscometer at temperatures of 25, 35, 45, and 55°C. The polymer used was Pusher-500 at a concentration of 1.798wt%. The emulsifying agent (Triton X-100) concentrations were fixed at 0.125, 0.25, 0.5, 0.75, 1.0, 1.5, and 2vol%. A general equation relating the emulsion viscosity to the shear rate and temperature was developed. The equation was used to determine the Metzner and Reed parameters (n' and k').

Microencapsulation using poly (L-lactic acid) II: Preparative variables affecting microcapsule properties

Poly (L-lactic acid) [L-PLA] microcapsules containing phenobarbitone were prepared from a w/o emulsion system, using light liquid paraffin as the continuum and a solution of phenobarbitone and L-PLA in acetonitrile as the disperse phase. Increasing stirring rate and emulsifying agent concentration were found to reduce microcapsule size. Spans (sorbitan esters of fatty acids) and Brijs (polyoxy ethylene ethers of fatty acids) with different physicochemical properties have been found to produce microcapsules of differing size. An attempt has been made to correlate emulsifier properties and the corresponding microcapsule size. It was found that the emulsifiers had little or no effect on the interfacial tension between light liquid paraffin and acetonitrile and there was no correlation between HLB of the emulsifiers and the resulting microcapsule size. It was postulated that microcapsule size would be affected by the packing of the emulsifier at the interface which would depend on the structure of the emulsifier. Closer, more uniform packing by the straight chain saturated fatty acid containing emulsifiers produced smaller microcapsules than when lose packing, which existed when emulsifiers containing either three fatty acid chains or a 'V' shaped cis-double bond containing fatty acid chain, were used. Microcapsule size was found to increase rapidly with an increase in polymer concentration, if this polymer concentration was increased in conjunction with an increase in the total solid content of the dispersed phase. Increases in polymer concentration by reducing the quantity of solvent for the dispersed phase caused little increase in mean microcapsule size. The phenobarbitone content in the microcapsules was not affected significantly by variations in the preparative parameters.

Lubricating Properties of Oil-In-Water Emulsions

Experiments are described in which elastohydrodynamic and boundary lubrication properties of O/W emulsions of mineral oil are studied with a variety of nonionic surfactants as the emulsifying agents. The changes in the minimum elastohydrodynamic film thickness are determined with different surfactants, with changes in oil concentration, with changes in emulsifying agent concentration, and with blending of different surfactants. These results can be quantitatively explained by a theory which assumes trapping of oil particles between steel surfaces with a certain probability. It is then shown that this trapping probability is correlated to the 'displacement energy' at the oil-water-steel boundaries. On the other hand, boundary lubrication properties of the emulsions are exclusively governed by those of the surfactants themselves suggesting that, under these lubricating conditions, their adsorbed films play a dominant role. Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/ST...

Liquid-liquid dispersion on mechanical agitation. 3. Effect of the emulsifying agent

This paper deals with effect of impeller velocity and emulsifying agent concentration on dispersion process. The apparatus consists of a cylindrical vessel (dt=150 mm) made of clear acrylate resin and Rushton-type impeller (di=49 mm). Water and a mixture of n-C7H16 and CCl4 were used as the continuous phase and the dispersed phase. Tween-20 and Tween-81 were employed as the emulsifying agent, and their concentration was 1%, 10-2%, 10-3% and 10-4%. Agitation was continuously done for 60 min, and revolution of the agitator was 330, 400, 530, or 660 rpm. The photographs of droplets were taken by a microscopic method, and the particle size distribution was calculated. The results obtained were as follows. 1) The normalized standard deviation was smaller with increasing concentration of the emulsifying agent, and the droplet size became uniform. 2) Irrespective of the concentration of emulsifying agent, surface energy Es had a constant value. 3) Experimental equation relative to the mean surface-volume diameter, d32, surface tension γ, revolution number N, and agitation time θ wa as follows : [numerical formula]

Liquid-liquid dispersion on mechanical agitation. IV. Effect of the emulsifying agent on W-O-type emulsion

This paper deals with the effect of impeller velocity and emulsifying agent concentration on W/O-type emulsion. The apparatus consists of a cylindrical vessel (d=150mm) made of clear acrylate resin and Rushton-type impeller (d=49mm). Water and a mixture of n-C7H16 and CCl4 were used as dispersed phase and continuous phase. Span-20, Span-40, or Span-85 was emuployed as an emlsifying agent, and its concentration was 3, 1, 0.3, 0.1, or 10-2% (w/w). The mixture was agitated continuously for 60min, and the revolution number was in the range of 330 to 812rpm. The photographs of droplets were taken by a microscopic method, and the particle size distribution was calculated. The following results were obtained by this experiment. 1) Effect of emulsifying agent on W/O-type dispersion became better in the order of Span-20, Span-40, and Span-85. 2) Surface energy, Es, was in proportion to three-seconds power of agitation intensity, U, and is expressed as follows : log Es=3/2 log U+α' 3) If agitation energy is expressed by EA, energy efficiency of the dispersion η would be defined by the following equation : η=ES/EA As the mean length diameter decreases, the energy efficiency η will show a smaller value.

The influence of emulsifying agent concentration on emulsion viscosity

The viscosity of emulsions is affected by the concentration of emulsifying agent normally employed in their preparation. This applies to both oil-in-water and water-in-oil systems. The effect is not constant for all emulsions that contain the same constituents irrespective of volume concentration disperse phase. On the contrary, it increases as the emulsions become more concentrated. The magnitude of the change with increasing disperse phase concentration depends on the type of emulsion and the chemical structure of the emulsifying agent. An equation is proposed that relatesη rel exponentially to both volume concentration of disperse phase and concentration of the emulsifying agent.