Redispersible Dry Emulsion Research Articles

Characterization of quinoa starch nanoparticles as a stabilizer for oil in water Pickering emulsion.

Quinoa starch nanoparticles (QSNPs) prepared by nanoprecipitation had a uniform particle size of 191.20nm. QSNPs with amorphous crystalline structure had greater contact angle than QS with orthorhombic crystalline structure, which can therefore be utilized to stabilize Pickering emulsions. QSNPs-based Pickering emulsions prepared by suitable formulations (QSNPs concentration of 2.0-2.5%, oil volume fraction of 0.33-0.67) exhibited good stability against pH of 3-9 and ionic strength of 0-200mM. The oxidative stability of the emulsions increased with increasing starch concentration and ionic strength. Microstructural and rheological results indicated that the structure of the starch interfacial film and the thickening effect of the water phase affected the emulsion stability. The emulsion had excellent freeze-thaw stability and can be produced as a re-dispersible dry emulsion using the freeze-drying technique. These results implied that the QSNPs had great potential for application in the preparation of Pickering emulsions.

Fabrication and characterization of highly re-dispersible dry emulsions

Highly re-dispersible dry emulsions were obtained through drying konjac glucomannan (KGM) or monoglyceride (MG) structured O/W emulsions. Emulsion powders showed different morphologies, particle size and surface microstructures, depending on the drying method (spray/freeze-drying), and the emulsion compositions. The introduction of a low level of KGM (0.15 wt%) and MG (1 wt%) significantly reduced the level of maltodextrin as wall material. All powdered emulsions showed rapid re-hydration in water. Compared with original emulsions before drying, re-constituted emulsions from spray-dried powders showed slightly increased mean droplet size while that from freeze-dried ones showed slightly decreased mean droplet size. KGM significantly decreased the initial viscosity (p < 0.05) but increased the creaming stability (p < 0.05) of re-constituted emulsions. Measurement of β-carotene content in re-constituted oil droplets fractions indicated that emulsion powders have good re-dispersibility in water (>93% in average). The findings in this study make it possible to obtain emulsion powders and their reconstitutions with desired properties by structuring the original emulsions before drying, and confirmed the possibility of KGM and MG in producing low-cost emulsion powders and the potential of these dry emulsions as novel solid delivery carriers for lipophilic components.

Redispersible dry emulsions stabilized by plant material: Rapeseed press-cake or cocoa powder

This work aimed at valorizing by-products of the agrifood industry: powders deriving from rapeseed press-cakes and cocoa. Novel oil-in-water emulsions stabilized by these vegetal powders were formulated and were dehydrated by freeze-drying and spray-drying. Dry emulsions of at least 40% oil content and with a moisture content below 2.6 wt% were obtained. Dry-emulsions did not exhibit any clumping even after several months of storage at room temperature, and were redispersible in water. To compare the ability of the drying process to preserve the state of dispersion, the size distributions of the oil droplets were compared before dehydration and after redispersion of the dry emulsions in an aqueous phase. Several oil-to-vegetal powder weight ratios were probed, and the impact of a solid filler –lactose– was investigated.

Improving dissolution and photostability of resveratrol using redispersible dry emulsion: Application of design space for optimizing formulation and spray-drying process

A redispersible dry emulsion (DE) containing resveratrol (RVT) was developed using low-methoxy pectin (LMP) and caprylic/capric glyceride (CCG) as the emulsifier and component comprising the lipid phase, respectively. The effects of formulation and the pump speed of spray dryer on the resultant redispersed emulsion size, angle of repose, and spraying efficiency were investigated and optimized using the Box–Behnken design. Redispersibility was used to estimate dissolution properties of RVT-DE. Experimental results showed that the size of the redispersed emulsion was affected by LMP and CCG concentrations. An increase and decrease in LMP and CCG concentrations, respectively, resulted in smaller emulsion droplet size and more rapid drug dissolution from RVT-DE. The angle of repose in RVT-DE was also influenced by LMP and CCG concentrations. RVT-DE generated using low LMP concertation and high CCG concentration showed a low angle of repose, indicating good flow property. An optimized formulation containing 2.75% w/w of LMP and 7% w/w of CCG sprayed at a pump speed of 10.1 mL/min prepared within design space satisfied all criteria i.e. small redispersed size, good flow, and high spraying efficiency. The photostability of RVT in RVT-DE was significantly higher than that in intact RVT.

A redispersible dry emulsion system with simvastatin prepared via fluid bed layering as a means of dissolution enhancement of a lipophilic drug

The purpose of the study was to develop a redispersible dry emulsion, containing a lipophilic, poorly water soluble model drug simvastatin, by employing fluid bed coating technology. The presented dry emulsion manufacturing approach produces pellets in a way, where a layer of the dry emulsion is applied to a neutral core. In the preliminary formulation development phase 1-oleoyl-rac-glycerol was chosen as the oily lipid phase, based on the high drug solubility and potential bioavailability enhancement capability. Mannitol, HPMC and Tween 20 were selected as the solid carriers and surfactant, respectively. The design of experiments, specifically the mixture design approach, was used to obtain the optimal formulation composition. The emulsion reconstitution ability and stability were the main responses, used as the decisive parameters for formulation optimisation. Optimised formulations showed narrow droplet size distribution upon reconstitution, high stability, suitable drug loading and enhanced dissolution profile, compared to a non-lipid based tablet and the pure drug. The scanning electron microscopy, Raman spectroscopy and image analysis disclosed a uniform morphology of the applied layer with separated droplets with simvastatin and uniform size distribution and a circular shape of coated pellets. The study represents the proof of concept of designing redispersible dry emulsions using a fluid bed layering approach.

Oral absorption of a valsartan-loaded spray-dried emulsion based on hydroxypropylmethyl cellulose

The aim of this study was to develop a novel valsartan-loaded spray-dried emulsion based on hydroxypropylmethyl cellulose (HPMC) with enhanced oral absorption. The valsartan-loaded redispersible dry emulsion was prepared by using a high-pressure homogenization and spray-drying process with water, Capryol 90, HPMC, and different surfactants, based on the results of the solubility study. The spray-dried emulsions formed small and homogeneous emulsions with a mean droplet emulsion size ranging from 133.5 to 152.5nm at the dispersion state in water. The valsartan-loaded redispersible dry emulsion with HPMC/poloxamer 407 showed enhanced pH-independent valsartan release, resulting in a dramatically enhanced oral bioavailability of valsartan compared to the raw material and commercial product. Therefore, a formulation strategy using the redispersible dry emulsion with HPMC/poloxamer 407 is very effective for the development of a new dosage form containing valsartan.

Preparation, characterization and in vitro intestinal absorption of a dry emulsion formulation containing atorvastatin calcium

A redispersible dry emulsion (DE) formulation of atorvastatin calcium (AC) was developed to enhance the in vitro dissolution of AC, thereby increasing its gastrointestinal absorption. The spray-drying technology was used where Plurol Oleique CC 497 was chosen as the oil phase. Effects of carriers, surfactants, and homogenizers on the characteristics of DE containing AC were systematically investigated. The final formulation consisted of dextrin and Poloxamer 188 as carrier and surfactant, respectively, and was homogenized by a high pressure homogenizer before spray drying. The in vitro release of AC from the optimized DE was significantly higher than that of pure AC powder (76% vs. 30% at 24 hr). The in vitro intestinal absorption of AC from the DE formulation was 0.77 μg/cm2 at 2 hr, which was a 2.33-fold increase compared to the pure unformulated AC powder. These results suggest that the oral dry emulsion formulation could improve the intestinal absorption of AC.

Preparation of redispersible dry emulsion using Eudragit E100 as both solid carrier and unique emulsifier

To improve the patient's compliance and the physical stability of liquid emulsion, a novel dry emulsion being able to reform the original O/W-emulsion by reconstitution in artificial gastric fluid is presented. Dry emulsions were prepared by spreading liquid O/W-emulsions on a flat glass, dried at the oven maintained at 40 °C and then triturated to powders with suitable particle size. When the dry emulsions were immersed into gastric fluid, stable emulsions were formed in 5 min. Here a sole excipient, high polymer, was applied as both solid carrier and unique emulsifier, and Zedoary turmeric oil (ZTO) was used as a model drug. In this study the effects of different kinds of high polymers on the liquid emulsion and on the dispersibility of the dry emulsions were investigated. Eudragit E100 exhibited the best emulsifying ability and the dry emulsion prepared with it shows the quickest release property. And the mean emulsion droplet sizes of the original emulsions and the reconstruction emulsions were <1 μm. Here the basic properties of the polymers, such as contact angle and relative viscosity, were also investigated. With this method it was easy to prepare redispersible dry emulsion from liquid oil content up to 45%.

Improvement of bioavailability and photostability of amlodipine using redispersible dry emulsion

To improve the bioavailability and photostability of poorly water-soluble and photosensitive amlodipine, dry emulsion (DE) was prepared by spray-drying the oil-in-water emulsion of amlodipine. Labrafil M 1944 CS and dextrin were employed as oil phase and matrix material, respectively. Dispersing DE in distilled water formed an emulsion with a mean droplet size 1.4-fold larger than that of the homogenized amlodipine emulsion before spray-drying (0.24 ± 0.30 μm versus 0.17 ± 0.02 μm). The mean droplet size of DE remained unchanged during 6-month storage at room temperature. 94.4% versus 33.1% of amlodipine remained intact after 24-h UV irradiation of amlodipine as DE formulation or as powder. These data suggest that DE formulation greatly improved the photostability of amlodipine, as well as increasing the physical stability of emulsion systems. In vitro release of DE was higher than that of amlodipine powder (66% versus 48% release at 60 min). Consequently, DE formulation resulted in 2.6- and 2.9-fold higher C max and AUC 0–24 h of amlodipine compared after oral administration of amlodipine powder in rats. Our data suggest that the DE may be a potential oral dosage form for amlodipine to improve its bioavailability.

Physical stability of redispersible dry emulsions containing amorphous sucrose

The objective of the present study was to estimate the stability of redispersible dry emulsions containing amorphous sucrose. Dry emulsions were prepared by spray drying liquid o/w-emulsions in a laboratory spray dryer. The effect of hydroxypropyl methylcellulose (HPMC) on the glass transition temperature T g of spray dried sucrose-HPMC mixtures, relative to the T g of amorphous sucrose, was investigated. For the sucrose-HPMC mixtures the values of T g followed the ideal Gordon-Taylor equation up to 30% HPMC. For dry emulsions containing 40% HPMC, 30% lipid and 30% sucrose, the T g was increased by 12°C relative to the T g of amorphous sucrose. The stability of the dry emulsions was investigated by a conventional stability study and by an enthalpy relaxation study. The measured enthalpy recovery of amorphous sucrose below T g was used to calculate molecular relaxation time parameters based on the Williams-Watts equation. The molecular mobility of amorphous sucrose at temperatures 50°C below T g was low and negligible with respect to the shelf life stability. It was concluded that the dry emulsions are physically stable with respect to the lifetime of a pharmaceutical product when stored in dry condition and at temperatures up to 28°C.

Preparation of redispersible dry emulsions by spray drying

Development of stable dry emulsions being able to reform the original o/w-emulsion by reconstitution in water is presented. Dry emulsions were prepared by spray drying liquid o/w-emulsions in a laboratory spray dryer. Three hydroxypropylmethylcellulose (HPMC) types were applied as solid carrier and emulsifier. The lipid phase was fractionated coconut oil. The ratio of solid carrier to lipid phase influenced the reconstitution properties. It was possible to prepare redispersible dry emulsions of a lipid content up to 40% dry powder mass. The different HPMC types had no noticeable effect on the reconstitution properties, but too viscous liquid o/w-emulsions were difficult to atomise. The type of rotary atomizer, or the rate of rotation did not affect the technical properties of the dry emulsions containing 40% lipid. It was concluded that low viscosity HPMC was a useful solid carrier. The dry emulsions remained physically stable for at least 6 months.

Technical optimisation of redispersible dry emulsions

Preparation of dry emulsions suitable for tablet processing was examined in this study. Liquid o/w-emulsions were spray dried in a laboratory spray dryer applying hydroxypropylmethylcellulose (HPMC) as a solid carrier and emulsifier. As the lipid phase, fractionated coconut oil was used. The ability of various excipients to increase the density of dry emulsions was investigated. Adding sucrose to the formulation, redispersible dry emulsions with higher density were obtained. The type of rotary atomizer did not affect the dry emulsions containing sucrose nor the rate of rotation of the atomizer applied in the spray drying process. By wet granulation, using ethanol as a binder, free-flowing and compactable dry emulsions were obtained and simultaneously the reconstitution properties were preserved. It was concluded that dry emulsions could be optimised for tablet processing by wet granulation. Tablets having a lipid content up to 20% had proper tablet properties.

Improvement of photostability of ubidecarenone in the formulation of a novel powdered dosage form termed redispersible dry emulsion

Ubidecarenone, which has low photostability and is poorly absorbed in the intestine, was formulated into a novel powdered dosage form designated as a redispersible dry emulsion. In preparing the system, an oily solution containing the drug and a colorant emulsified in an aqueous solution of a surfactant (Pluronic F-68) were spray-dried with a suitable excipient. The resultant dry emulsion particles have good flow properties and readily release the oily droplets to form stable emulsions on rehydration. The redispersibility, i.e., the conversion to the original emulsion from the dry emulsion form, was found to be closely related to the viscosity of the oily carrier. The photostability of the drug dissolved in the oily carriers was much improved in the presence of colorants. The kinetics data for photolytic degradation of the drug in the dry emulsion particle were analyzed to clarify the effect of the amount of excipient and colorant on the photostability of the drug in the particle.

Design of Redispersible Dry Emulsion as an Advanced Dosage Form of Oily Drug (Vitamin E Nicotinate) by Spray-Drying Technique

AbstractAn oily drug, dl-α-tocopherol nicotinate (VEN) was transformed to the newly developed powdered form, termed dry emulsion, by spray-drying the emulsified VEN or oily solutions of VEN with additives. The drug releasing property from the resultant particles was dependent on various factors such as the emulsifying method and the type and amount of the oily carrier and surfactant formulated. The desired releasing property was offered by use of medium chain triglyceride (MCT) as the oily carrier and polyoxyethylene-polyoxypropylene-blockcopolymer (Pluronic F-68) or polyoxyethylenesorbitan monolaulate (Tween 80) as the emulsifying agent. The difference in drug releasing property with various formulations was found to be mainly attributed to the difference in physical state of VEN surfactant in the dry emulsion particle, which was detected by differential scanning calorimetry.

Redispersible Dry Emulsion System as Novel Oral Dosage Form of Oily Drugs: In Vivo Studies in Beagle Dogs.

The absorption characteristics of vitamin E acetate (VEA) formulated into a dry emulsion system after its oral administration to beagle dogs were determined and compared to those of two different dosage forms (an oily mixture of the drug with cottonseed oil and an oil (drug)-in-water emulsion). The three dosage forms were administered in a crossover fashion to six nonfasting subjects, and the drug absorption was assessed from the plasma concentration of the major metabolite (free vitamin E). VEA formulated in the dry emulsion was rapidly absorbed, which suggested that a considerable amount was released as reformed emulsion droplets in the gastrointestinal tract as well as in water in vitro. Based on the analysis of variance, no significant differences in bioavailability parameters (AUC, Cmax or Tmax) were observed among the three dosage forms.