Properties Of Microemulsions Research Articles

Monitoring the formation kinetics of a bicontinuous microemulsion

HypothesesThe performance of bicontinuous microemulsions is usually assessed on the characteristics of the middle phase at equilibrium. However, applied to Enhanced Oil Recovery, such an evaluation would not be representative of the structure and composition of fluids in reservoir rocks. Studies on the properties of non-equilibrated microemulsions are still needed to better understand the formation of such complex systems, in particular to optimize input parameters of process simulation tools. ExperimentsFor this purpose, we monitored the formation of a microemulsion from contact with the oil to equilibrium when no mixing or convection is provided. Non-destructive methods such as Nuclear Magnetic Resonance, Micro-Computed Tomography, Dynamic Light Scattering and Small Angle X-ray scattering were used to extract the compositions, phase thicknesses, dynamics and structures of the system over time. FindingWe found that the system gets structured into several layers over time that include the transient presence of an oriented semi-crystalline phase. The growth of the bicontinuous middle phase results from a progressive reorganization of the liquid crystal. The compositional and structural gradients, observed along the sample height, are correlated and linked to the corresponding structures of the phase diagram of the quaternary system. Equilibrium is reached after the total transfer of the liquid crystal into the bicontinuous phase.

Microemulgel: a novel approach for topical drug delivery

Topical drug delivery is mostly preferred for dermatological action. Topical dosage form such as cream, ointments, gels etc. has certain drawbacks like stability problems, stickiness, poor absorption as well as permeability. It has limitations in terms of drug solubility, residence time, lipophilicity and permeability. To overcome this, a novel approach microemulsion based gel is formulated. Microemulgel is topical drug delivery system that incorporates the properties of both gel and microemulsion and shows dual release control system. The microemulgel is prepared by reducing the globule size of the emulsion (less than 200nm) so that the drug particles can easily penetrate through stratum corneum. In spite of penetration, microemulgel has several advantages like easily spreadable, non-grease, thixotropic, transparent, and bio-friendly. Currently many drugs of antimicrobial, antifungal and non-steroidal anti-inflammatory class are studied for topical delivery through microemulgel formulation. After the brief study, it can be concluded that the microemulgel appear better and effective delivery system as compared to other topical drug delivery system

Development of a BCS Class II Drug Microemulsion for Oral Delivery: Design, Optimization, and Evaluation

Our work is aimed at exploring the composition and the properties of microemulsion (ME), as a drug delivery system, to enhance the permeability across the gastrointestinal (GI) barrier of fenofibrate, a BCS class II drug. It is a prodrug that is converted rapidly after oral administration into a major active metabolite which is the fenofibric acid. It undergoes a nearly complete presystemic metabolism. Its main drawback is the low bioavailability of the metabolite. A quick selection of excipients was made based on the capacity of solubilization and the value of hydrophilic-lipophilic balance. The classical method of ME development was coupled with the factorial design in order to minimize the droplet size using a low concentration of surfactant. The optimized ME showed a droplet size of 48.5 nm and physical stability. The passive permeability evaluated using Sartorius was 1.6 times higher than that of the free drug. The ex vivo technique, performed using the everted gut sac model, showed a 2.5-fold higher permeability. This suggests that the carrier-mediated uptake/efflux may present the dominant transport mechanism of fenofibrate. The use of the excipients that inhibit GI P-glycoprotein may be a new perspective. Thus, this paper shows that the composition and the characteristics of ME may be explored to increase the permeability of fenofibrate across the GI membrane.

Using Microemulsions: Formulation Based on Knowledge of Their Mesostructure.

Microemulsions, as thermodynamically stable mixtures of oil, water, and surfactant, are known and have been studied for more than 70 years. However, even today there are still quite a number of unclear aspects, and more recent research work has modified and extended our picture. This review gives a short overview of how the understanding of microemulsions has developed, the current view on their properties and structural features, and in particular, how they are related to applications. We also discuss more recent developments regarding nonclassical microemulsions such as surfactant-free (ultraflexible) microemulsions or ones containing uncommon solvents or amphiphiles (like antagonistic salts). These new findings challenge to some extent our previous understanding of microemulsions, which therefore has to be extended to look at the different types of microemulsions in a unified way. In particular, the flexibility of the amphiphilic film is the key property to classify different microemulsion types and their properties in this review. Such a classification of microemulsions requires a thorough determination of their structural properties, and therefore, the experimental methods to determine microemulsion structure and dynamics are reviewed briefly, with a particular emphasis on recent developments in the field of direct imaging by means of electron microscopy. Based on this classification of microemulsions, we then discuss their applications, where the application demands have to be met by the properties of the microemulsion, which in turn are controlled by the flexibility of their amphiphilic interface. Another frequently important aspect for applications is the control of the rheological properties. Normally, microemulsions are low viscous and therefore enhancing viscosity has to be achieved by either having high concentrations (often not wished for) or additives, which do not significantly interfere with the microemulsion. Accordingly, this review gives a comprehensive account of the properties of microemulsions, including most recent developments and bringing them together from a united viewpoint, with an emphasis on how this affects the way of formulating microemulsions for a given application with desired properties.

Bursting the bubble: A molecular understanding of surfactant-water interfaces.

Surfactant science has historically emphasized bulk, thermodynamic measurements to understand the microemulsion properties of greatest industrial significance, such as interfacial tensions, phase behavior, and thermal stability. Recently, interest in the molecular properties of surfactants has grown among the physical chemistry community. This has led to the application of cutting-edge spectroscopic methods and advanced simulations to understand the specific interactions that give rise to the previously studied bulk characteristics. In this Perspective, we catalog key findings that describe the surfactant-oil and surfactant-water interfaces in molecular detail. We emphasize the role of ultrafast spectroscopic methods, including two-dimensional infrared spectroscopy and sum-frequency-generation spectroscopy, in conjunction with molecular dynamics simulations, and the role these techniques have played in advancing our understanding of interfacial properties in surfactant microemulsions.

Enhanced ocular delivery of clotrimazole via loading into mucoadhesive microemulsion system: In vitro characterization and in vivo assessment

This work aimed to formulate clotrimazole (CLZ), a water-insoluble antifungal drug, into a chitosan-coated microemulsion system for achieving enhanced ocular delivery. In this study, CLZ loaded microemulsions were firstly prepared according to 22 × 31 full factorial design in order to investigate the influence of different formulation variables on microemulsion properties. The selected microemulsion formulation (F4: oleic acid, Cremophor EL: Transcutol HP (1:1) and water (20, 70 and 10%, w/w, respectively)) showed nanosized spherical globules with a droplet size of 229.1 ± 0.989 nm, polydispersity index of 0.5085 ± 0.0095, and zeta potential of −33.3 ± 0.98 mV. The selected microemulsion was then coated with low molecular weight chitosan to increase the contact time with the eye surface. In vivo studies in albino rabbits demonstrated the superiority of chitosan-coated microemulsion over the uncoated microemulsion and drug suspension formulation concerning sustainment of antifungal activity over the eye surface. Moreover, the in vivo, ocular tolerance and histopathological studies conducted using male albino rabbits proved the safety of the prepared microemulsions after topical ocular application. Generally, the obtained results confirmed that CLZ chitosan-coated microemulsion could be promising for ocular CLZ delivery.

Evaluation of Physicochemical and Antifungal Properties of Microemulsions of Lemongrass Oil (Cymbopogon citratus) and Clove Oil (Syzygium aromaticum)

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Preparation and properties of dodecylamine microemulsion for the flotation of quartz and magnetite

Dodecylamine (DDA) can only be used with acidification in the reverse flotation of iron ore. To solve this problem, this paper proposed a novel water-in-oil microemulsion with DDA prepared using one or two of AEO-3, OP-10, and Tween-80 & Span-80 as the surfactants, 2-octanol as the cosurfactant, and DDA and kerosene as the oil phase. The freezing point, surface tension, droplet size distribution, and zeta potential were determined for the DDA microemulsion. The results showed that the freezing point of the produced DDA microemulsion can be reduced to –12.5 °C. Moreover, the surfaces of its droplets dispersed in aqueous solution are positively charged at pH values less than 10.0. The flotation performance of the DDA microemulsion was investigated by flotation tests. From the results, DDA microemulsion exhibited good dispersibility and surface activity, thereby confirming its ability to effectively reduce air–water interfacial tension. In addition, it was found to have good adaptability to temperature and pulp pH, yielding a magnetite concentrate with 68.54% Fe and 3.60% SiO2 from magnetite with 64.93% Fe and 9.12% SiO2 using 45 g/t DDA microemulsion. Therefore, the proposed DDA microemulsion can be used as an efficient collector in the reverse flotation of magnetite.

Study on tribological behavior, lubrication and anti-corrosion properties of W/O microemulsion for cold rolling of copper strip

PurposeThe purpose of this paper is to improve lubrication and anti-corrosion properties of the water-in-oil (W/O) microemulsion for rolling of copper strip and sheet to replace the traditional rolling oil.Design/methodology/approachThe W/O microemulsion is prepared by using hydrogenated base oil, a deionized aqueous solution of 0.03 mol/L of Na2SO4 and composite emulsifier such as Sp20, Tx-7 or sodium petroleum sulfonate. Tribological behavior of the microemulsions and traditional cold rolling oil was conducted by MR-10A four-ball tester. The lubrication performance of microemulsion for cold rolling of copper strip was performed by cold-rolling experiment. The morphology of worn surface and the rolled copper was characterized. Anti-corrosion properties of microemulsion for rolled copper was investigated, and the corroded surface was analyzed by X-ray photoelectron spectrometer (XPS).FindingsThe results show that the extreme pressure and antiwear properties of the microemulsions have been improved; the average friction coefficient of the improved microemulsion is 0.065, which is 30% lower than the commercial cold rolling oil. For cold rolling of copper strip, the microemulsion has a higher thinning effect than the commercial cold rolling oil, and a smooth surface is obtained and the surface roughness (Sa) is decreased by 6.8%. The XPS analysis indicated microemulsion adsorbed on the copper surface mitigate the corrosion of oils.Originality/valueThis paper used the prepared W/O microemulsion as a new lubricant in the process of rolling for copper strip and sheet in industry, demonstrating the microemulsion has broad application prospects in the future.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2020-0227/

Formulation and tribological behavior of ultra-low sulfur diesel fuels microemulsified with glycerin

The lubricity of diesel is a fundamental parameter, as it has a direct impact on the engine operation, working life and wear of the parts. Ultra-low sulfur diesel fuels (ULSD) have low lubricity due to the removal of polar compounds resulted from the desulfurization process. This study evaluated the impact of glycerin addition on the lubrication properties of ULSD microemulsion fuel. Lubricity tests were developed in High Frequency Reciprocating Rig (HFRR). The results showed that, when compared to the ULSD reference fuel with 10 ppm sulfur, the addition of glycerin at the highest concentration was capable to double the percentage of lubricant film formation, reduce by 48% the wear scar formed in the steel ball and promote the reduction in the values of roughness parameters by approximately 50%.

Effect of hydrophobically modified PEO polymers (PEO-dodecyl) on oil/water microemulsion properties: in vitro and in silico investigations.

Microemulsions are excellent systems for transdermal delivery of multifunctional drugs because they have the potential to improve drug absorption/permeation and handling limitations. Biocompatible polymers are used as a coating of microemulsions to avoid the interactions that can occur between the microemulsions and the skin. Thus, they protect and lubricate these transporter nanovesicles. In this paper, we studied decane/water microemulsions covered with hydrophobically modified PEO polymer (PEO-m). To reveal the effect of hydrophobically modified PEO (PEO-m) polymer on the shape, the micro-arrangement and the dynamics of the microemulsions, we used an integrated strategy combining Molecular Dynamics simulation (MD), Small-Angle Neutron Scattering experiments (SANS), and the Ornstein–Zernike integral equations with the Hypernetted Chain (HNC) closure relation. We determined the microemulsion shape in vitro using the renormalized intensities spectra from SANS experiments. We discussed the micro arrangements of microemulsions, in vitro and in silico, employing the pair correlation function g(r) and the structure factor S(q), obtained from the three approaches with good agreement. Thus, we used the validated MD simulations to calculate the microemulsion's dynamics properties that we discussed using the mean-squared displacement (MSD) and the diffusion coefficients. We found that the presence of moderate quantities of PEO-m, from 4 to 12 PEO-m per microemulsion, does not influence the microemulsion shape, increases the stability of the microemulsion, and slightly decrease the dynamics. Our in vitro and in silico results suggest that polymer incorporation, which has interesting in vivo implications, has no disadvantageous effects on the microemulsion properties.

Molecular Thermodynamics for Aggregation of Surfactants with Alkylbenzene or Branched Alkane Tails: An Experimental-Modeling Approach

This work presents a molecular thermodynamic approach in which microemulsion properties are obtained by minimizing the total Gibbs energy of the system. Notably, this optimization process is carried out mainly based on the surfactant molecular structure and the solution conditions. Even though molecular thermodynamic modeling has been widely applied to oil-in-water (O/W) microemulsions, just a few studies are reported on water-in-oil (W/O) microemulsions mainly focused on ionic surfactants with linear alkyl tails. Here, we investigate the self-aggregation of different non-ionic surfactants with more complex structures acting as hydrophobic tails. In this context, we model the phase behavior of alkylphenol ethoxylate surfactant systems incorporating liquid-vapor and liquid-liquid data of alkylbenzenes from the literature. As a result, we can optimize the model parameters and describe the equilibrium micelle structure. The particle swarm optimization method was applied to minimize the Gibbs free energy for both O/W and W/O microemulsions. In order to evaluate the predictive performance of the model, we compared the experimental data with the computed critical micelle concentration and micelle size.

Formulation and Evaluation of Microemulsion Based in Situ Gel of Acyclovir for Vaginal Delivery

The purpose of the present study was to formulate and evaluate microemulsion based in situ gel of Acyclovir (ACV) for the vaginal delivery. The solubility of ACV in oils and surfactants and co-surfactant was evaluated to identify the components of the microemulsion. Microemulsion region was determined by using the pseudo-ternary phase diagrams for different formulations. Microemulsion formulation was prepared using Labrafil M1994C as oil phase, Cremophor RH40 as surfactant and Polyethylene glycol 400 and Transcutol P as co-surfactant and water. Microemulsion formulations were evaluated for pH, viscosity, conductivity and stability study. In situ gel of ACV, microemulsion was prepared using thermosensitive polymer, poloxamer.In situ gelwas characterized for viscosity, gelling temperature, the effect of dilution on gelling temperature, gelling ability, and in vitro drug release and release kinetics. The globule size of developed microemulsion was less than 100 nm with PDI in the range 0.307 to 0.641. The optimized microemulsion based in situ gel demonstrated shear thinning behaviour, the gelation temperature with and without dilution was in the range of 30-35ºC, and the drug release was sustained over eight hours. Mucoadhesive properties of microemulsion based in situ gel formulations were determined with a texture analyzer using a goat vaginal tissue, and the results indicated that the presence of microemulsion increased the mucoadhesion significantly. Microemulsion based in situ gel was successfully developed for vaginal delivery of Acyclovir.

Development and Evaluation of Cucurbitacin B Microemulsion: the Effect of Oil Phase and Aqueous Phase on Drug Percutaneous Absorption Based on ATR-FTIR Spectroscopy and Molecular Modeling.

The present study aimed to develop a cucurbitacin B microemulsion (CuB-ME) and investigate the mechanism of the enhanced drug skin absorption at themolecular level. Firstly, the pseudo-ternary phase diagrams were developed to evaluate the effect of composition on microemulsion properties systematically. The formulation composition types and ratios of oil phase, surfactant, co-surfactant, and aqueous phase were optimized by an in vitro skin permeation experiment, and the optimized formula was confirmed with the pharmacodynamics study. Furthermore, the molecular mechanism of enhanced skin permeation was investigated using ATR-FTIR and molecular modeling. As a result, the optimized CuB-ME formulation was composed of Azone:Tween 80:ethanol:water = 2.5:16.9:5.6:75.0 (w/w/w/w). The oil phase improved skin permeation by disordering the stratum corneum intercellular liquid, while the aqueous phase impacted the particle size of the microemulsion and permeability coefficient of the drug. Besides, the hydration state of skin lipid also enhanced drug permeation by the interaction of water and the polar head of ceramide. The in vitro skin permeation amount was 45.47 ± 10.39μg/cm2, and no significant skin irritation was observed. The pharmacodynamics study demonstrated that CuB-ME had a significant therapeutic effect on the animal tumor model. In conclusion, the CuB-ME was developed successfully and the effect of the oil phase and aqueous phase on drug skin permeation was clarified at themolecular level.

Nose-to-Brain Delivery of Diazepam from an Intranasal Aqua-Triggered In-Situ (ATIS) Gelling Microemulsion: Monitoring Brain Uptake by Microdialysis.

An innovative intranasal aqua-triggered in-situ (ATIS) gel is a polymer-free in-situ gelling microemulsion which gels instantaneously on contact with minute quantities of water to form a mucoadhesive gel. The objective of the study was to develop ATIS diazepam (ATIS-diazepam) as an alternative to the injection for epileptic emergencies and evaluate its brain uptake and nose-to-brain targeting efficiency in rats. ATIS-diazepam (1mg/100 µL) was prepared and characterized for in vitro formulation characteristics. An LC-MS/MS method was developed and validated for the bioanalysis of diazepam. In vivo studies for pharmacokinetics, brain uptake and nasal irritation of intranasal ATIS-diazepam were conducted in rats. Brain uptake was investigated with brain microdialysis, a highly sensitive technique enabling quantification of free drug, which correlates to efficacy. ATIS-diazepam exhibited globule size < 200nm, low viscosity, negative zeta potential and good stability. A significant increase in mucoadhesion was exhibited by ATIS-diazepam following the addition of a small quantity of water. ATIS-diazepam showed burst release in pH 6.4 with 50% diazepam release in ~ 10min, which was sustained over 1h. The absolute bioavailability was ~ 50% with both intranasal free-diazepam and ATIS-diazepam. Intranasal administration of ATIS-diazepam revealed immediate absorption with rapid and high brain extracellular fluid concentration compared to intravenous free-diazepam solution. The estimated direct transport potential and drug targeting efficiency of intranasal ATIS-diazepam was significantly higher (2-fold) than intranasal free-diazepam solution, which was attributed to the mucoadhesive and microemulsion properties of ATIS-diazepam. The nasal irritation study revealed the safety of ATIS-diazepam compared to free-diazepam solution. Intranasal ATIS-diazepam showed promise of higher direct nose-to-brain targeting, better safety and hence has an immense implication in the treatment of epileptic emergencies.

Development and Physico-Chemical Evaluations of Clove Oil Microemulsions

Clove oil, extracted from dried floral buds of clove (Syzygium aromaticum), are used in topical products because it has antioxidant and antimicrobial activities. Microemulsions (ME) are stable emulsion which can be formulated by simple mixing of oil, water, surfactant and co-surfactant. The objectives of this research were to develop and evaluate clove oil-loaded ME for topical application by using Tween 80 as surfactant. Ethanol, isopropanol and propylene glycol (PG) were used as co-surfactants. Pseudo ternary-phase diagram showed that using ethanol and isopropanol provided larger ME area than using PG in all surfactant:co-surfactant ratio (SR; 1:0.5, 1:1 and 1:2). Up to 20% w/w of clove oil can be loaded in ME by using surfactant mixture of 60-80% w/w. The effects of various amounts of clove oil (5-20%) and surfactant mixture (60, 70, 80%) at SR of 1:1 on physico-chemical properties of ME were observed. All formulations are transparent with the pH values of 6.8-8.0. The droplets size of ME using ethanol and isopropanol as co-surfactant ranged from 10-100 nm while that using PG was higher. Conductivity values showed that all formulations were o/w ME. Zeta potential values revealed stable particles. For ethanol and isopropanol, ME containing 5-10% clove oil and 60-70% SM showed good physico-chemical stability. The amount of eugenol in clove oil analyzed by gas chromatographic (GC-FID) method was 82.27% v/v. The stability test of selected formulations (70% surfactant mixture at SR = 1:1) was evaluated from %eugenol remaining at room temperature and in refrigerator after 4-week storage. It was found that the amount of eugenol in the formulation was effected by the storage condition. Our results indicate that clove oil can be prepared in ME with physico-chemical stability by using Tween 80 and ethanol as surfactant system.

Enhancement of Antioxidant Activity by the Combination of &lt;i&gt;Moringa oleifera &lt;/i&gt;and &lt;i&gt;Perilla frutescens&lt;/i&gt; Seed Oils in Microemulsion

The aim of this study was to investigate the synergistic antioxidant activity of microemulsion containing mixed Moringa oleifera seed oil and Perilla frutescens seed oils, compared with microemulsion of single oils. The novel microemulsions for the moringa, perilla, and mixed seed oils were formulated by mixing appropriate amount of surfactant, water, and oil phase. The formulation containing the maximum amount of oil which appeared transparent was further evaluated for particle size, size distribution, surface charge, pH, and rheological behavior. The in vitro antioxidant properties of microemulsions were investigated in comparison with essential oils. Cream containing microemulsion was prepared and its physical stability was investigated by heating-cooling cycles. The results showed that the maximum content of oil incorporated in microemulsion system was 12.5%. The mean droplet sizes of moringa, perilla, and mixed oil microemulsion were 159.33±0.77, 183.86±1.42, and 263.43± 9.40 nm, respectively. All formulations exhibited pseudoplastic flow behavior. The mixture of moringa and perila seed oils in microemulsion possessed the highest significant antioxidant effect against 1,1-diphenyl-2-picrylhydrazyl compared with single oil microemulsion. The cream containing microemulsion exhibited good physical stability. Thus, the current research reveals the benefits of microemulsion containing mixed moringa and perilla seed oils based cream compared with single essential oils.

Template-mediated self-assembly of magnetite-gold nanoparticle superstructures at the water-oil interface of AOT reverse microemulsions

HypothesisBimetallic magnetite-gold nanostructures are interesting candidates to combine and enhance individual properties of each metal element in catalytic and analytical applications. Microemulsions have been employed in templated synthesis of nanoparticles, and their combination with different types of nanoparticles can further mediate interactions at the water-oil interface, providing new forms of hybrid nanostructures. ExperimentsReverse water-in-oil microemulsions of droplet sizes below 50 nm were prepared from ternary mixtures of Aerosol-OT (AOT) as surfactant, incorporating 4 nm sized superparamagnetic nanoparticles (MNPs) to the hexane-pentanol oil phase and 5 nm sized polyethyleneimine-stabilized gold nanoparticles (Au(PEI)-NPs) to the water phase. The resulting isotropic L2 phase, Winsor phases and organized nanostructures were investigated using conductometry, calorimetry, UV–Vis spectroscopy, cryo-SEM and HRTEM. FindingsDroplet-droplet interactions, morphology and surfactant film properties of AOT microemulsions could be modulated in different ways by the presence of the different nanoparticles from each liquid phase. Additionally, phase separation into Winsor phases allows the formation upon solvent evaporation of films with bimetallic heterostructures on the micrometer scale. This demonstrates a new way of nanoparticle templated assembly at liquid interfaces by assisted interactions between microemulsions and nanoparticles, as a promising strategy to obtain thin films of small, isotropic nanoparticles with hierarchical ordering.

Molecular dynamics study on microstructure of supercritical CO2 microemulsions containing ionic liquids

Supercritical CO2 microemulsions containing ionic liquid have been widely used in materials preparation, wastewater treatment, biological medicine, and other fields due to its polar microenvironment successfully constructed in the non-polar environment. The focus of this research is to study the microstructure and thermodynamic properties of the microemulsion system through molecular dynamics simulation, with the aim of further expanding its application. Therefore, it is essential to study microstructure at first. In this paper, molecular dynamics simulations were performed to investigate the thermodynamic properties of supercritical CO2 microemulsions containing three different ionic liquids ([bmim][PF6], [bmim][BF4], and [bmim][Ac]) and surfactant Ls-mn (dodecyl polyoxyethylene (m) polyoxypropylene (n) ether) in the presence or absence of water. The simulation results identified the necessary condition for preparing scCO2 microemulsion containing ILs as presence of water. For the quaternary system, the fixed ILs content and surfactant concentration had the optimal water content value. Moreover, in the core area, except for the ionic liquid domain, part of the water was also dissolved. Simultaneously, the stretching angle of the surfactant tail chain and the radius of each system were significantly different. Ultimately, the comparative analysis of scCO2/H2O/ILs microemulsion systems based on Ls-mn hydrocarbon surfactants was conducted, and the system aggregation change law of the m/n ratio was proposed. When the m/n ratio of surfactants is smaller, that is, the hydrophilic EO groups are the less, the faster the aggregation rate of surfactants is, the higher the aggregation efficiency is, but the less the amount of water captured by clusters will be. The Ls-36 system used only 12 ns to complete the aggregation process, and the system could achieve 100 % aggregation efficiency within 150 ns. However, this system had the least amount of captured water, only 93.75 %.

Disruption of Lipid Bilayers of Stratum Corneum by Transdermal Delivery of Glipizide in Microemulsion and Binary Co-solvent Systems

The study was designed to develop and characterize structured vehicles for effective delivery of glipizide (GPZ) through excised stratum corneum (SC). Several mixed binary systems of ethanol or propylene glycol (PG) were prepared by homogeneous mixing with double distilled water. Different microemulsions were prepared by titration method and their physicochemical properties determined. Transdermal permeation of GPZ was studied in-vitro using modified Franz diffusion cells. Apart from the slight difference in their pH values, there was no significant difference in the physicochemical properties of the drug-loaded coconut oil-based microemulsions and their blank counterparts. Transdermal flux was highest in binary mixtures of 9:1 (v/v) aqueous ethanol (Jss 30.25 ± 5.75 μg/cm2h) and PG (Jss 6.34 ± 1.29 μg/cm2h) compared to their lower strengths. Transdermal GPZ flux, Jss, μg/cm2h was higher in o/w (121.2 ± 9.98) compared to w/o (3.89 ± 0.19) microemulsions with enhanced permeation of ≥ 23 fold using patch size of 10.45 cm2. Biophysical analysis of untreated and treated SC showed that GPZ permeation could depend on the extent of disruption of lipid and protein bilayers of SC by the vehicles. Cremophor RH 40/ethanol/coconut oil-based o/w microemulsion and 9:1 v/v mixed binary systems of ethanol or PG are promising vehicles for delivery of GPZ transdermally.&#x0D; Dhaka Univ. J. Pharm. Sci. 19(1): 29-35, 2020 (June)