Microemulsion-based media as novel drug delivery systems

Preparation and characterization of microemulsions formulated with PEG fatty acid glycerides

Microemulsions are thermodynamically stable and homogeneously dispersed systems formed spontaneously by water, oil, surfactants, and co-surfactants at specific proportions under specific conditions. Microemulsions can not only dissolve certain active ingredients to achieve protection and slow release, but also effectively promote their transdermal absorption, further improving the bioavailability due to the nanoscale of the emulsion droplets. In this study, microemulsions formulated with surfactant polyethylene glycol (PEG) fatty acid glycerides were prepared and the effects of oil property, the amphiphilicity of surfactant, the types of co-surfactants, the main/co-surfactant mixing ratio (Km) as well as the temperature, pH, ionic strength of the systems on the phase behavior of the studied system were discussed in the framework of the pseudo-ternary phase diagram. The results indicate that lower polarity oils are more likely to form microemulsions constructed by PEG fatty acid glycerides. The formation of microemulsion depends much on the amphiphilicity of surfactant; PEG fatty acid glycerides with higher hydrophile-lipophile balance (HLB) facilitate the formation of microemulsions. The shorter the chain length of co-surfactant (alcohols), the easier it is for the formation of microemulsion. For alcohols with a certain number of carbon chains, the fewer the hydroxyl groups, the easier it is to form microemulsions. This study identifies an optimal Km of 2:1. Based on the fact that PEG fatty acid glycerides are nonionic surfactants, the prepared microemulsions have a good tolerance to pH fluctuations (pH 4-9) and keep stable within a wide temperature range, which enable the microemulsions to be applied in variable environments. The higher concentration salt inhibits microemulsion formation in some degree though the lower concentration salt has no obvious effect on the formation of microemulsion. Furthermore, the types of microemulsions in the single-phase region were further identified, and the microstructure of microemulsions formulated with PEG fatty acid glycerides was investigated by transmission electron microscopy (TEM). Typical spherical oil-in-water (O/W) microemulsions, uniformly distributed water-in-oil (W/O) microemulsions, and the characteristic network structure of bicontinuous microemulsions were observed. On this basis, the water-soluble nicotinamide was singled out to study the transdermal behavior of substance in oil-in-water microemulsion and in traditional emulsion. The results indicate that the substance in microemulsion have better transdermal property compared with conventional emulsion. The present work provides not only fundamental information for the preparation of microemulsions formulated with PEG fatty acid glycerides but also the reference for its application in practice.

Self-Emulsifying delivery systems for oral administration of exenatide: Hydrophobic ion pairs vs. Dry reverse micelles

This research provides a comparative analysis of two innovative strategies - hydrophobic ion pairing (HIP) and dry reverse micelles (dRM) - to enhance the oral bioavailability of exenatide, a GLP-1 receptor agonist, as a diabetes treatment. These techniques were integrated into self-emulsifying drug delivery systems (SEDDS) featuring a lipid matrix composed of propylene glycol dilaurate and salicylic acid methyl ester (32.5 %:32.5 %; v/v) with polyethoxylated-35 castor oil (35 %; v/v) as surfactant. HIP enhances the lipophilicity of exenatide through ion-pairing with cationic surfactants, thereby promoting efficient incorporation into the lipid matrix of SEDDS. In contrast, dRM forms stabilized micellar structures using sorbitan monooleate, improving safety and compatibility. The droplet sizes for SEDDS were analyzed via dynamic light scattering and varied from 95 to 110 nm, with a polydispersity index of approximately 0.25, and zeta potentials between -1 mV and -6 mV. The maximum log DSEDDS/AQ values were 2.13 ± 0.31 for exenatide-loaded HIPs (ExeHIP) and 2.05 ± 0.08 for exenatide-loaded dRM (ExedRM), indicating sufficient lipophilicity, which is crucial for effective absorption and bioavailability. Toxicological assessments showed low toxicity levels. In vivo studies indicated a relative bioavailability of 18.08 % for ExeHIP and 17.06 % for ExedRM compared to intravenous injection. Both strategies demonstrated a similar potential in relative bioavailability, reflecting a significant increase in bioavailability compared to the control. Notably, the HIP formulation provided better control over exenatide release and ensured stable GLP-1 levels, while dRMs are preferable for safety reasons as all excipients have GRAS status and are therefore FDA approved.

Exploring the antidiabetic effect of various therapeutic essential oils synergistically with repaglinide

OBJECTIVE

This study aimed to evaluate the antidiabetic efficacy of microemulsions formulated with cardamom oil, black seed oil, and olive oil. The goal was to determine the optimal formulation for stable microemulsions and assess their potential as innovative drug delivery systems for the antidiabetic drug repaglinide.

METHODS

Initial phase diagrams were constructed to identify the optimal ratios of oil, water, surfactant (Tween 80), and cosurfactant (ethanol) for producing stable microemulsions. The physical attributes of the resulting formulations, such as droplet size, zeta potential, and morphology, were characterized using transmission electron microscopy. Drug release profiles of microemulsions containing repaglinide were evaluated using the dialysis method. Moreover, vivo studies were conducted to assess the therapeutic efficacy of cardamom oil microemulsions compared to standard commercial repaglinide formulations.

RESULTS

Microemulsions exhibited suitable properties with optimal particle size, well-defined spherical droplets, and optimized zeta potential. Drug release studies indicated that cardamom oil-based microemulsions demonstrated superior release characteristics, providing a more sustained and controlled release of repaglinide compared to microemulsions containing black seed or olive oil. In vivo studies revealed a significant improvement in antidiabetic outcomes with cardamom oil microemulsions over standard commercial repaglinide formulations. The enhanced efficacy was attributed to improved bioavailability and the controlled release properties of the drug.

CONCLUSION

This research underscores the potential of cardamom oil-based microemulsions as effective antidiabetic drug delivery systems. With superior physicochemical properties and controlled release profiles, they promise innovative treatment options for diabetes, potentially improving therapeutic outcomes for patients.

Eco-Friendly high Drug-Loading microemulsions with Incorporation of Deep eutectic Solvents: Advancing precision with the dual Ouzo effect

Deep eutectic solvents (DES) enhance drug solubility but require delivery systems, while the Ouzo effect enables surfactant-free microemulsion formation despite limitations in oil phase ratio. By integrating DES as the oil phase, this study develops a dual Ouzo effect microemulsion system that induces both microemulsions and nanoprecipitations simultaneously. Through detailed analysis of composition diagrams, precise adjustment of the mass ratio of VA64 to propylene glycol enables strict control over particle size from 200 nm to 550 nm. This approach enhanced curcumin's solubility to 17.11 mg/mL, a 1700-fold increase compared to its water solubility, with excellent stability showing only 22.4 % degradation after 4 h of light exposure (versus 90-95 % in conventional carriers). The system increased the cumulative release amount of curcumin and presented a rapid initial release followed by a sustained release. Compared with traditional Ouzo effect systems, introducing DES significantly increased the oil phase ratio from 0.05 % to 30 % through enhanced molecular interactions and supersaturation. DES composition adjustment enabled microemulsion stabilization without complex processing, achieving optimal stability with a three-phase contact angle of 89.2° (±0.3°), approaching the theoretical ideal value of 90° for interface stability.

Characterizing the Complex Multi-Step Degradation Kinetics of Amphotericin B in a Microemulsified Drug Delivery System

Amphotericin B (AmB), a potent amphiphilic drug with antifungal and antileishmanial properties, exhibits reduced nephrotoxicity when delivered via lipid-based systems like microemulsions (ME). However, the complexity of these multi-phasic systems challenges the use of simple schemes and models for describing AmB degradation. The aim of this study was to establish a degradation scheme and model for AmB within a ME, alongside a control micellar formulation. AmB degradation pathways and models in both lipidic and aqueous systems were evaluated based on prior research. Experimental investigations into interface degradation pathways were conducted using a micellar approach. High-Performance Liquid Chromatography (HPLC) was employed for AmB quantification. Oxidation emerges as the principal degradation pathway within micelles, dependent on surfactant-induced aggregation. Considering AmB's behavior in distinct media (lipidic, aqueous, and micellar), an empirical degradation scheme is proposed, translated into a complex multi-pathway mathematical model capable of describing experimental data on AmB degradation in ME under dark conditions. Aggregation and oxidation played significant roles, and kinetic constants were calculated for AmB in ME. The model presented here represents a significant step toward accurately describing the non-linear degradation of AmB in prospective liquid lipid-based dispersions, potentially advancing its market prospects.

Pequi Pulp (Caryocar brasiliense) Oil-Loaded Emulsions as Cosmetic Products for Topical Use

The pequi (Caryocar brasiliense) is a typical fruit from the Brazilian Cerrado. From it, pequi pulp oil is extracted, a valuable product for cosmetic applications due to its high levels of unsaturated fatty acids and carotenoids. Carotenoids are antioxidant compounds that are easily oxidized. To improve pulp stability, emulsification techniques with carboxymethylcellulose at 1% (w/w) were used to encapsulate the pequi pulp oil at 1, 3, 5% (w/w), and 8% (w/w) of polysorbate 80® using a high-rotation mechanical stirrer. The pequi pulp oil was first characterized by FTIR and GC-MS. The results indicated the presence of chemical groups characteristic of the oil itself and the presence of a large proportion of fatty acids, which are essential for the maintenance of cutaneous hydration and the barrier, also acting in the tissue repair process. All emulsions presented stable over 120 days with slightly acidic pH values and were compatible with human skin. The droplet diameter was less than 330 nm, and the polydispersity index was around 0.3, indicating systems with low polydispersity. The Zeta potential (ζ) exhibited negative values sufficient to stabilize the emulsified systems. All emulsions behaved as non-Newtonian fluids, presenting pseudo-plastic and thixotropic properties that are considered important for topical applications.

Understanding Microemulsions and Nanoemulsions in (Trans)Dermal Delivery

Continuously explored in pharmaceuticals, microemulsions and nanoemulsions offer drug delivery opportunities that are too significant to ignore, namely safe delivery of clinically relevant drug doses across biological membranes. Their effectiveness as drug vehicles in mucosal and (trans)dermal delivery is evident from the volume of published literature. Commonly, their ability to enhance skin permeation is attributed to dispersion size, a characteristic closely related to solubilization capacity. However, the literature falls short on distinctions between microemulsions and nanoemulsions for definitions, behavior, or specific differences in their mechanisms of action in (trans)dermal delivery. The focus is typically on surfactant/cosurfactant ratio and droplet size but the role of mesostructures or the effect of cosolvent (Csol), oil (O) or water (W) on permeation profile remain poorly explained. Towards a deeper understanding of these vehicles in (trans)dermal drug delivery, this review begins with their conceptual and practical distinctions before delving into the published works for less obvious but potentially important underlying mechanisms; notably composition and the competitive positioning of system constituents in the resulting microstructures and subsequent effect(s) these may have on skin structures and drug permeability. For practical purposes, this review focuses on formulation systems based on ternary diagrams with commonly accepted non-ionic surfactants, cosurfactants, cosolvents, and oils used in pharmaceutical applications.

Development of a fish oil-nanoemulsion gel as a drug-delivery system to prevent capsular contracture

Capsular contracture, a significant complication of breast-implant surgery, causes pain and deformation following the formation of a tight capsule around an implant. Current surgical and non-surgical treatment options are invasive, expensive, and typically administered for prolonged periods, potentially leading to side effects. To address these challenges, we developed a novel fish oil-encapsulated, poloxamer-based nanoemulsion gel with omega-3 (ω3) as the primary active component (NE-ω3 gel; N3G). This formulation can be injected during surgery, reducing the need for prolonged administration of medications and minimizing associated side effects. N3G was prepared through a two-step process involving the emulsification of fish oil followed by gelation with poloxamer to create a thermoreversible gel. Dynamic light-scattering analysis confirmed a uniform distribution of nanoemulsion particles, which had a mean diameter of 287 ± 8.599 nm and a PDI of 0.29 ± 0.047. FTIR and DSC analyses validated the encapsulation of fish oil within poloxamer micelles. Drug-release analysis demonstrated that more than 96% of fish oil was released within 10 h. In in vivo experiments, rats (n = 30) were divided into three groups: a negative control group (G1), a positive control group receiving fish oil (G2), and an experimental group with implants coated with N3G (G3). G3 exhibited a 21.2% reduction in capsular thickness compared to G1 and a 5.6% reduction compared to G2. In addition, significant decreases in fibrosis and myofibroblast counts were observed in G3. These results, supported by histological and gene expression analyses, highlight the effectiveness of N3G in reducing inflammation and fibrosis. This study underscores the therapeutic potential of N3G for capsular contracture, based on its persistence, thermoreversibility, and improved dosing and storage characteristics.

Locally Acting Budesonide-Loaded Solid Self-Microemulsifying Drug Delivery Systems (SMEDDS) for Distal Ulcerative Colitis

Background

Budesonide (BUD) is a BCS class II medication with poor water solubility and limited oral bioavailability. In this study, innovative solid self-microemulsifying drug delivery systems (BUD-SMEDDS) were developed for effective local management of distal ulcerative colitis (UC).

Methods

Based on solubility and emulsification tests, the components of the self-microemulsifying drug delivery system (SMEDDS) were Capryol™ 90, Tween 80, and Transcutol HP. The impacts of BUD-SMEDDS ingredients (as inputs) on the average globule size (AGS), polydispersity index (PDI), and self-emulsification time (SET) as responses were investigated using the Box-Behnken design methodology. Solid rectal systems were then fabricated using the optimized values of SMEDDS components in Lutrol® bases. The developed systems were evaluated for in vitro characteristics and in vivo efficacy using a rat colitis model.

Results

For all responses, the greatest impact was attributed to the oil content of SMEDDS. An optimized BUD-SMEDDS with AGS of 33 ± 2.9 nm, PDI of 0.29 ± 0.03 and SET of 25 ± 2.5 s) was selected for rectal formulations. The developed formulations demonstrated acceptable physical characteristics and mucoadhesive abilities. Differential scanning calorimetric (DSC) analysis revealed the absence of BUD crystallinity in the SMEDDS formulations. The drug release patterns could be regulated by selecting the grade and composition of the incorporated Lutrols. Clinical and histopathological assessments revealed considerable improvements in animals treated with BUD-SMEDDS formulations.

Conclusion

Overall findings confirmed the superior capability of solid SMEDDS as BUD carriers to manage distal colitis in tested animals.

Recent progress in nanoparticulate-based intranasal delivery for treating of different central nervous system diseases

Drug administration to the central nervous system (CNS) has become a great obstacle because of several biological barriers, such as the blood-brain barrier, therefore, brain targeting insights are a light for scientists to move forward for treating neurogenerative diseases using advanced non-invasive methods. The current demand is to use a potential direct route as the nasal administration to transport drugs into the brain enhancing the BBB permeability and hence, increasing the bioavailability. Interestingly, recent techniques have been implanted in formulating nanocarriers-based therapeutics for targeting and treating ischemic stroke using lipid or polymeric-based materials. Nanoparticulate delivery systems are set as an effective platform for brain targeting as polymeric nanoparticles and polymeric micelles or nanocarriers based on lipids for preventing drug efflux to promote optimal therapeutic medication concentration in the brain-diseased site. In recent years, there has been a notable increase in research publications and ongoing investigations on the utilization of drug-loading nanocarriers for the treatment of diverse CNS diseases. This review comprehensively depicts these dangerous neurological disorders, drug targeting challenges to CNS, and potential contributions as novel intranasal nano-formulations are being used to treat and regulate a variety of neurological diseases.

Novel functions of o-cymen-5-ol nanoemulsion in reversing colistin resistance in multidrug-resistant Klebsiella pneumoniae infections

Multidrug resistance (MDR) Klebsiella pneumoniae (K. pneumoniae) is a major emerging threat to human health, and leads to very high mortality rate. The effectiveness of colistin, the last resort against MDR Gram-negative bacteria, is significantly compromised due to the widespread presence of plasmid- or chromosome-mediated resistance genes. In this study, o-cymen-5-ol has been found to greatly restore colistin sensitivity in MDR K. pneumoniae. Importantly, this compound does not impact bacterial viability, induce resistance, or cause any noticeable cell toxicity. Various routes disclosed the potential mechanism of o-cymen-5-ol potentiating colistin activity against MDR K. pneumoniae. These include inhibiting the activity of plasmid-mediated mobile colistin resistance gene (mcr-1), accelerating lipopolysaccharide (LPS) - mediated membrane damage, and promoting the ATP-binding cassette (ABC) transporter pathway. To enhance the administration and bioavailability of o-cymen-5-ol, a nanoemulsion has been designed, which significantly improves the loading efficiency and solubility of o-cymen-5-ol, resulting in antimicrobial potentiation of colistin against K. pneumoniae infection. This study has revealed a new understanding of the o-cymen-5-ol nanoemulsion as a means to enhance the effectiveness of colistin against resistant factors. The finding also suggests that o-cymen-5-ol nanoemulsion could be a promising approach in the development of potential treatments for multidrug-resistant Gram-negative bacterial infections.

Characterization of 10MAG/LDAO reverse micelles: Understanding versatility for protein encapsulation

Reverse micelles (RMs) are spontaneously organizing nanobubbles composed of an organic solvent, surfactants, and an aqueous phase that can encapsulate biological macromolecules for various biophysical studies. Unlike other RM systems, the 1-decanoyl-rac-glycerol (10MAG) and lauryldimethylamine-N-oxide (LDAO) surfactant system has proven to house proteins with higher stability than other RM mixtures with little sensitivity to the water loading (W0, defined by the ratio of water to surfactant). We investigated this unique property by encapsulating three model proteins - cytochrome c, myoglobin, and flavodoxin - in 10MAG/LDAO RMs and applying a variety of experimental methods to characterize this system's behavior. We found that this surfactant system differs greatly from the traditional, spherical, monodisperse RM population model. 10MAG/LDAO RMs were discovered to be oblate ellipsoids at all conditions, and as W0 was increased, surfactants redistributed to form a greater number of increasingly spherical ellipsoidal particles with pools of more bulk-like water. Proteins distinctively influence the thermodynamics of the mixture, encapsulating at their optimal RM size and driving protein-free RM sizes to scale accordingly. These findings inform the future development of similarly malleable encapsulation systems and build a foundation for application of 10MAG/LDAO RMs to analyze biological and chemical processes under nanoscale confinement.

Inhaled Nanoparticulate Systems: Composition, Manufacture and Aerosol Delivery

An increasing growth in nanotechnology is evident from the growing number of products approved in the past decade. Nanotechnology can be used in the effective treatment of several pulmonary diseases by developing therapies that are delivered in a targeted manner to select lung regions based on the disease state. Acute or chronic pulmonary disorders can benefit from this type of therapy, including respiratory distress syndrome (RDS), chronic obstructive pulmonary disease (COPD), asthma, pulmonary infections (e.g. tuberculosis, Yersinia pestis infection, fungal infections, bacterial infections, and viral infections), lung cancer, cystic fibrosis (CF), pulmonary fibrosis, and pulmonary arterial hypertension. Modification of size and surface property renders nanoparticles to be targeted to specific sites, which can serve a vital role in innovative pulmonary drug delivery. The nanocarrier type chosen depends on the intended purpose of the formulation and intended physiological target. Liquid nanocarriers and solid-state nanocarriers can carry hydrophilic and hydrophobic drugs (e.g. small molecular weight drug molecules, large molecular weight drugs, peptide drugs, and macromolecular biological drugs), while surface modification with polymer can provide cellular targeting, controlled drug release, and/or evasion of phagocytosis by immune cells, depending on the polymer type. Polymeric nanocarriers have versatile architectures, such as linear, branched, and dendritic forms. In addition to the colloidal dispersion liquid state, the various types of nanoparticles can be formulated into the solid state, offering important unique advantages in formulation versatility and enhanced stability of the final product. This chapter describes the different types of nanocarriers, types of inhalation aerosol device platforms, liquid aerosols, respirable powders, and particle engineering design technologies for inhalation aerosols.

Evaluation of the effects of a dasatinib-containing, self-emulsifying, drug delivery system on HT29 and SW420 human colorectal carcinoma cells, and MCF7 human breast adenocarcinoma cells

Background/Aim

Dasatinib (DS), a second-generation tyrosine kinase inhibitor, functions as a multi-target small-molecule drug via targeting various tyrosine kinases involved in neoplastic cell growth. DS inhibits cancer cell replication and migration, and induces tumor cell apoptosis in a variety of solid tumors. However, it is poorly soluble in water under some pH values. Therefore, the development of a DS-containing, self-emulsifying, drug delivery system (SeDDs) could help overcome these problems in treating cancer cells.

Methods

Various SeDD formulations loaded with DS were developed with isopropyl myristate (oil phase), Labrafil (surfactant), and polyethylene glycol (co-surfactant). The physicochemical properties of the formulations were assessed according to droplet size, encapsulation efficiency, and in vitro drug release. The cytotoxicity of the formulations on the cancer cell lines HT29 and SW420 (human colorectal carcinoma), and MCF7 (human breast adenocarcinoma), in addition to MRC5 normal human fetal lung fibroblasts, was evaluated to assess selectivity.

Results

The DS-SeDD formulation showed favorable particle size, encapsulation efficiency, and in vitro drug release. The anti-cancer potency of DS-SeDDs had greater cytotoxicity effects than pure DA on the three cancer cell lines, MCF7, HT29, and SW420l.

Conclusion

The developed DS-SeDD formulations may potentially be an effective sustained drug delivery method for cancer therapy.

Quality-by-design-based microemulsion of disulfiram for repurposing in melanoma and breast cancer therapy

Aim: The current study aims to develop and optimize microemulsions (ME) through Quality-by-Design (QbD) approach to improve the aqueous solubility and dissolution of poorly water-soluble drug disulfiram (DSF) for repurposing in melanoma and breast cancer therapy.Materials & methods: The ME was formulated using Cinnamon oil & Tween® 80, statistically optimized using a D-optimal mixture design-based QbD approach to develop the best ME with low vesicular size (Zavg) and polydispersity index (PDI).Results: The DSF-loaded optimized stable ME showed enhanced dissolution, in-vitro cytotoxicity and improved cellular uptake in B16F10 and MCF-7 cell lines compared with their unformulated free DSF.Conclusion: Our investigations suggested the potential of the statistically designed DSF-loaded optimized ME for repurposing melanoma and breast cancer therapy.

Microemulsion-Based Polymer Gels with Ketoprofen and Menthol: Physicochemical Properties and Drug Release Studies

Ketoprofen is a non-steroidal, anti-inflammatory drug frequently incorporated in topical dosage forms which are an interesting alternatives for oral formulations. However, due to the physiological barrier function of skin, topical formulations may require some approaches to improve drug permeation across the skin. In this study, ketoprofen-loaded microemulsion-based gels with the addition of menthol, commonly known for absorption-enhancing activity in dermal products, were investigated. The main objective of this study was to analyze the physicochemical properties of the obtained gels in terms of topical application and to investigate the correlation between the gel composition and its mechanical properties and the drug release process. Microemulsion composition was selected with the use of a pseudoternary plot and the selected systems were tested for electrical conductivity, viscosity, pH, and particle diameter. The polymer gels obtained with Carbopol® EZ-3 were subjected to rheological and textural studies, as well as the drug release experiment. The obtained results indicate that the presence of ketoprofen slightly decreased yield stress values. A stronger effect was exerted by menthol presence, even though it was independent of menthol concentration. A similar tendency was seen for hardness and adhesiveness, as tested in texture profile analysis. Sample cohesiveness and the drug release rate were independent of the gel composition.

Development and Optimization of Dipyridamole- and Roflumilast-Loaded Nanoemulsion and Nanoemulgel for Enhanced Skin Permeation: Formulation, Characterization, and In Vitro Assessment

This study explores developing and optimizing a nanoemulsion (NE) system loaded with dipyridamole and roflumilast, aiming to improve skin penetration and retention. The NE formulation was further transformed into a nanoemulgel to enhance its application as a topical treatment for psoriasis. Solubility studies were conducted to select the oil, surfactant, and co-surfactant. Phase diagrams were constructed using the aqueous phase titration method. All the formulations were in nanoscale, and Formula (F2) (which contains oleic acid oil as the oil phase, a mixture of Surfactant Tween 80 and co-surfactant (ethanol) at a ratio of 1:2 in addition to distilled water as an aqueous phase in a ratio of 1:5:4, respectively) was the selected formula depending on the particle size, PDI, and zeta potential. Formula (F2) has the best ratio because it gives the smallest nanoemulsion globule size (particle size average of 167.1 nm), the best homogenicity (lowest PDI of 0.195), and the highest stability (higher zeta potential of -32.22). The selected formula was converted into a nanoemulgel by the addition of 0.5% (w/w) xanthan gum (average particle size of 172.7 nm) and the best homogenicity (lowest PDI of 0.121%) and highest stability (higher zeta potential of -28.31). In conclusion, the selected formula has accepted physical and chemical properties, which enhanced skin penetration.

Surfactant Synergistic Effect and Interfacial Properties of Microemulsions Compounded with Anionic and Nonionic Surfactants Using Dissipative Particle Dynamics

Microemulsions are one of the most promising directions in enhanced oil recovery, but conventional screening methods are time-consuming and labor-intensive and lack the means to analyze them at the microscopic level. In this paper, we used the Clint model to predict the changes in the synergistic effect of the mixed system of anionic surfactant sodium dodecyl benzenesulfonate and nonionic surfactant polyethoxylated fatty alcohols (C12E6), generated microemulsions using surfactant systems with different mole fractions, and used particle size to analyze the performance and stability of microemulsions, analyze the properties and stability of microemulsions using particle size, and analyze the interfacial behaviors and changes of microemulsions when different systems constitute microemulsions from the point of view of mesoscopic microemulsion self-assembly behaviors by combining with dissipative particle dynamics. It has been shown that microemulsion systems generated from anionic and nonanionic surfactants with a synergistic effect, based on the Clint model, exhibit excellent performance and stability at the microscopic level. The method proposed in this paper can dramatically improve the screening efficiency of microemulsions of anionic and nonanionic surfactants and accurately analyze the properties of microemulsions, so as to provide a theoretical basis for the subsequent research on microemulsions.

Continuous Synthesis of Nanoscale Emulsions by Vapor Condensation (EVC)

Emulsions are widely used in many industrial applications, and the development of efficient techniques for synthesizing them is a subject of ongoing research. Vapor condensation is a promising method for energy-efficient, high-throughput production of monodisperse nanoscale emulsions. However, previous studies using this technique are limited to producing small volumes of water-in-oil dispersions. In this work, a new method for the continuous synthesis of nanoscale emulsions (water-in-oil and oil-in-water) is presented by condensing vapor on free-flowing surfactant solutions. The viability of oil vaporization and condensation is demonstrated under mild heating/cooling using diverse esters, terpenes, aromatic hydrocarbons, and alkanes. By systematically investigating water vapor and oil vapor condensation dynamics on bulk liquid-surfactant solutions, a rich diversity of outcomes, including floating films, nanoscale drops, and hexagonally packed microdrops is uncovered. It is demonstrated that surfactant concentration impacts oil spreading, self-emulsification, and such behavior can aid in the emulsification of condensed oil drops. This work represents a critical step toward advancing the vapor condensation method's applications for emulsions and colloidal systems, with broad implications for various fields and the development of new emulsion-based products and industrial processes.

Olive Oil-Based Reverse Microemulsion for Stability and Topical Delivery of Methotrexate: In Vitro

Hydrolysis of pharmaceutically active molecules can be in control under a confined environment of water-in-oil microemulsion. Stability of model drug methotrexate (MTX) in a sodium bis(2-ethylhexyl) sulfosuccinate (AOT) and olive oil microemulsion system has been evaluated. The physicochemical properties of AOT-MTX-water-olive oil reverse microemulsion (MTX-RM) were examined by UV-vis, Fourier transform infrared, and X-ray diffraction techniques, and the hydrodynamic size was determined by dynamic light scattering techniques and morphologies were characterized by a transmission electron microscope and atomic force microscope. In vitro permeation of MTX-RM through treated skin and its mechanism are evaluated by a UV-visible spectrophotometer, confocal laser scanning microscope, differential scanning calorimeter, and attenuated total reflecting infrared spectroscopy (ATR). The interaction of MTX with the AOT headgroup in confined environment RM enhanced the stability of MTX without affecting the molecular integrity at room temperature. Chemical stability of MTX in MTX-RM (W0 = 5) is significantly higher (∼97%) at room temperature for the study period of 1 year than in MTX-RM (W0 = 15) (∼72%). Interaction of MTX with the AOT headgroup is also visualized by a high-resolution transmission electron microscope and is in correlation with FT-IR data of MTX-RM. The skin fluxes of MTX are 15.1, 19.75, and 22.75 times higher at water content (W0) of 5, 10, and 15, respectively, in MTX-RM in comparison to aqueous solution of MTX. The enhanced amounts of the MTX were detected using CLSM in hair follicles, sweat glands, and epidermis layer of the skin. Merging of T2, T3, and T4 thermal peaks in one broad peak in treated skin endothermograph shows that carrier MTX-RM affects the lipid as well protein structure of the treated skin. ATR data of treated skin showed an increase in the intensity of the carbonyl peak at 1750 cm-1 (lipid), shifting of the amide II peaks, and separation of peaks in the range of 1060 to 1000 cm-1 (vibration mode of -CH2OH, C-O stretching, and C-OH bending peak of the carbohydrate) in comparison to control skin, which indicates that MTX-RM interacts with glycolipid and glycoprotein through carbohydrate hydroxy groups.

Fragrance in dermocosmetic emulsions: From microstructure to skin application

Fragrance is added to almost all dermocosmetic emulsions, as it has been found to be a key driver in consumer choice and contributes to the perception of product performance. Fragrance is a complex mixture of odorant chemicals at different concentrations. When incorporated into a formulation, the individual fragrance chemicals partition between the emulsion phases depending on their physicochemical properties, which can impact the structure, stability, texture and odour of the final product. On the other hand, it is well known in the food industry how the composition and structure of food emulsion matrices influence the release of aroma chemicals. Fragranced dermocosmetic emulsions have been studied to a lesser extent but it is interesting to apply findings from the food domain since emulsion structure, composition and aroma compounds share common features. This review aims to give an overview of the literature dealing with the interactions between fragrance and dermocosmetic emulsions. The effects of fragrance on emulsion microstructure, stability and texture are highlighted and discussed. The effects of composition and structure of emulsion on the release of fragrance molecules are also presented. Finally, the interactions between skin and fragranced emulsions are addressed.

Characteristics of Oil-in-Oil Emulsions under AC Electric Fields

Emulsions have been applied in a number of industries such as pharmaceutics, cosmetics, and food, which are also of great scientific interest. Although aqueous emulsions are commonly used in our daily life, oil-in-oil (o/o) emulsions also play an irreplaceable role in view of their unique physics and complementary applications. In this paper, we investigate typical behaviors of organic droplets surrounded by organic medium (o/o emulsions) with different functional groups controlled by the AC electric field. Droplet behaviors can be catalogued into five types: namely, "no effect", "movement", "deformation", "interface rupture", and "disorder". We identify the key dimensionless number Wee·Ca, combined with the channel geometry, for characterizing the typical behaviors in silicon oil/1,6-hexanediol diacrylate and mineral oil/1,6-hexanediol diacrylate emulsions. Unlike aqueous emulsion, the Maxwell-Wagner relaxation inhibits the electric effect and leads to an effective frequency, ranging from 0.5 to 3 kHz. The increasing viscosity of the droplet facilitates the escalation by promoting the shearing effect under the same flow conditions. Ethylene glycol droplets primarily show the efficient coalescence even at a low Wee·Ca, which is attributed to the attraction of free charges induced by the increasing conductivity. In 1,6-hexanediol diacrylate/silicon oil emulsion, the droplet tends to form a liquid film that expands into the entire channel due to the affinity of the droplet to the channel wall. A variety of elongated columns are observed to oscillate between the electrodes at high voltages. These findings can contribute to understanding the electrohydrodynamic physics in o/o emulsion and controlling droplet behaviors in a fast response, programmable, and high-throughput way. We expect that this droplet manipulation technology can be widely adopted in a broad range of chemical synthesis and biological and material science.

In vivo and in vitro transdermal availability of Ibuprofen using novel solubility enhancing fluid nanosized carrier systems

The objective of this study was to explore the benefits of transdermal drug delivery systems as an alternative option for patients who are unable to tolerate oral administration of drugs, such as ibuprofen (IB). To achieve this, nonionic surfactants and three cosolvents were employed to develop new microemulsions (MEs) that contained IB as nanocarriers. The aim was to enhance the solubility and bioavailability of the drug after transdermal administration. The MEs were characterised by droplet size, polydispersity index (PDI), and rheological properties. Furthermore, the flux of IB was evaluated by Franz diffusion cells using excised rat skin and in vivo bioavailability using rats. The results showed that the MEs had ideal viscosity and droplet size below 100 nm. Moreover, using the developed MEs, an improvement in the solubility (170 mg/mL) and flux through the rat skin (94.6 ± 8.0 µg/cm2.h) was achieved. In addition, IB demonstrated a maximum plasma level of 0.064 mg/mL after 8 h of transdermal administration in rats using the ME with an increase in the bioavailability of about 1.5 times in comparison to the commercial IB gel. In conclusion, the developed nonionic MEs containing IB can be ideal nanocarriers and promising formulations for the transdermal administration of IB.

Cationic microemulsion of voriconazole for the treatment of fungal keratitis: in vitro and in vivo evaluation

Aim: This investigation aimed to develop a voriconazole-loaded chitosan-coated cationic microemulsion (CVME) to treat fungal keratitis. Methods: Microemulsions were prepared using water titration, and the optimized microemulsion was coated with chitosan to prepare CVME. The physicochemical parameters, ocular irritation potential, in vitro antifungal efficacy and in vitro release studies were performed. The in vivo antifungal efficacy study was conducted in a fungal infection-induced rabbit eye model. Results: The developed CVME displayed acceptable physicochemical properties and excellent mucoadhesive behavior and showed a sustained release profile. Ex vivo and in vivo studies concluded that higher permeability and improved antifungal efficacy were observed for CVME than drug suspension (DS). Conclusion: The prepared CVME7 is a viable alternative to treating fungal keratitis with existing approaches.

Recent Advances in Nanocarrier-based Approaches to Atopic Dermatitis and Emerging Trends in Drug Development and Design

Atopic dermatitis (AD), commonly known as Eczema, is a non-communicable skin condition that tends to become chronic. The deteriorating immunological abnormalities are marked by mild to severe erythema, severe itching, and recurrent eczematous lesions. Different pharmacological approaches are used to treat AD. The problem with commercial topical preparations lies in the limitation of skin atrophy, systemic side effects, and burning sensation that decreases patient compliance. The carrier-based system promises to eliminate these shortcomings; thus, a novel approach to treating AD is required. Liposomes, microemulsions, solid lipid nanoparticles (SLNs), nanoemulsions, etc., have been developed recently to address this ailment. Despite extensive research in the development method and various techniques, it has been challenging to demonstrate the commercial feasibility of these carrier- based systems, which illustrates a gap among the different research areas. Further, different soft wares and other tools have proliferated among biochemists as part of a cooperative approach to drug discovery. It is crucial in designing, developing, and analyzing processes in the pharmaceutical industry and is widely used to reduce costs, accelerate the development of biologically innovative active ingredients, and shorten the development time. This review sheds light on the compilation of extensive efforts to combat this disease, the product development processes, commercial products along with patents in this regard, numerous options for each step of computer-aided drug design, including in silico pharmacokinetics, pharmacodynamics, and toxicity screening or predictions that are important in finding the drug-like compounds.

Amphiphilic Heterografted Molecular Bottlebrushes with Tertiary Amine-Containing Side Chains as Efficient and Robust pH-Responsive Emulsifiers

By combining the unique characteristics of molecular bottlebrushes (MBBs) and the properties of stimuli-responsive polymers, we show that MBBs with randomly grafted poly(n-butyl acrylate) and pH-responsive poly(2-(N,N-diethylamino)ethyl methacrylate) (PDEAEMA) side chains are efficient and robust pH-responsive emulsifiers. Water-in-toluene emulsions were formed at pH 4.0 and disrupted by increasing the pH to 10.0. The emulsion generation and disruption was reversible over the ten cycles investigated, and the bottlebrushes remained intact. The exceptional emulsion stability stemmed from the high interfacial binding energy of MBBs, imparted by their large molecular size and Janus architecture at the interface, as evidenced by the interfacial jamming and wrinkling of the assemblies upon reducing the interfacial area. At pH 10.0, PDEAEMA became water-insoluble, and the MBBs desorbed from the interface, causing de-emulsification. Consequently, we have shown that the judicious design of MBBs can generate properties of particle emulsifiers from their large size, while the responsiveness of the MBBs enables more potential applications.

Micro-nanoemulsion and nanoparticle-assisted drug delivery against drug-resistant tuberculosis: recent developments

Tuberculosis (TB) is a major global health problem and the second most prevalent infectious killer after COVID-19. It is caused by Mycobacterium tuberculosis (Mtb) and has become increasingly challenging to treat due to drug resistance. The World Health Organization declared TB a global health emergency in 1993. Drug resistance in TB is driven by mutations in the bacterial genome that can be influenced by prolonged drug exposure and poor patient adherence. The development of drug-resistant forms of TB, such as multidrug resistant, extensively drug resistant, and totally drug resistant, poses significant therapeutic challenges. Researchers are exploring new drugs and novel drug delivery systems, such as nanotechnology-based therapies, to combat drug resistance. Nanodrug delivery offers targeted and precise drug delivery, improves treatment efficacy, and reduces adverse effects. Along with nanoscale drug delivery, a new generation of antibiotics with potent therapeutic efficacy, drug repurposing, and new treatment regimens (combinations) that can tackle the problem of drug resistance in a shorter duration could be promising therapies in clinical settings. However, the clinical translation of nanomedicines faces challenges such as safety, large-scale production, regulatory frameworks, and intellectual property issues. In this review, we present the current status, most recent findings, challenges, and limiting barriers to the use of emulsions and nanoparticles against drug-resistant TB.

Double Emulsion-Mediated Delivery of Polyphenol Mixture Alleviates Atopic Dermatitis

Although the polyphenols have been studied to alleviate inflammation, there are still challenges to delivering the polyphenols with stabilized formulation due to their low water solubility and susceptibility to oxidation. Herein, the transdermal delivery system of polyphenol mixture (PM), including quercetin (Q), phloretin (P), and ellagic acid (E), is developed using double emulsion for applying to atopic dermatitis (AD). Through the in vitro anti-degranulation assay, the optimal molar ratio of each polyphenol (Q:P:E = 5:1:1) is obtained, and the PM shows at most a 43.6% reduction of degranulation of immune cells, which is the primary factor of AD. Moreover, the water-in-oil-in-water double emulsion (W/O/W) enhances the PM's stability and has a higher anti-degranulation effect than the oil-in-water emulsion (O/W). In the in vivo 1-chloro-2,4-dinitrobenzene (DNCB)-induced mice AD model, PM reduces more AD symptoms than every single polyphenol. The PM-encapsulated W/O/W (PM_W/O/W) shows the most effectiveness in AD by decreasing dermatitis score, i.e., skin/ear thickness, mast cells, and serum IgE level. Finally, this suggests that the findings on the optimal ratio of PM and double emulsion-based delivery would be beneficial in treating AD and can be applied to other allergic diseases.

Preparation, optimization and evaluation of Osthole transdermal therapeutic system

In the current study, the solubility and permeability of Osthole-loaded microemulsion were enhanced, which increased bioavailability. In addition, Carbomer 940 was added for prolonged drug delivery. The microemulsion was prepared after the screening of Kukui oil, Labrasol (surfactant), and transcutol-P (co-surfactant). Pseudoternary phase diagrams were employed to find the microemulsion region. Box Behnken Design (BBD) was employed for optimizing microemulsions. Variables were related and compared using mathematical equations and response surface plots (RSP). MEBG was then compared with control gel on the basis of stability studies, drug permeation, skin irritation studies, and anti-inflammatory studies. Microemulsion preparations depicted a pH of 5.27 - 5.80, a conductivity of 139 - 185 μS/cm, a poly-dispersity index of 0.116 - 0.388, a refractive index of 1.330 - 1.427, an average droplet size of 64 - 89 nm, homogeneity, spherical shape, viscosity 52 - 185 cP. Predicted values of Optimized microemulsions showed more reasonable agreement than experimental values. The microemulsion was stable and non-irritating on Rabbit skin. MEBG showed a significant difference from control gel for percent edema inhibition from the standard. The permeation enhancing capability of MEBG using a suitable viscosity fabricates it promising carrier for transdermal delivery of Osthole.

Sustained delivery of triamcinolone acetonide from a thermosensitive microemulsion gel system for the treatment of sensorineural hearing loss

Intratympanic administration for the delivery of steroids has been extensively studied but limited because of low permeability of the drug through the row window membrane. Here, to effectively deliver poorly soluble triamcinolone acetonide (TA), microemulsions (ME) were prepared from Capmul MCM (oil), Cremophor RH40 (surfactant), and tetraglycol (cosurfactant) based on solubility studies, emulsifying ability test, and pseudoternary phase diagrams. Microemulsion gel (MEG) was prepared by mixing TA-ME with a poloxamer hydrogel base. The physicochemical properties of ME and MEG formulations were characterized, and the toxicity and oto-protective effectiveness were evaluated in vitro and in vivo. The ME-3 formulation showed a small droplet size (16.5 ± 0.2 nm), narrow PDI (0.067 ± 0.041), and enhanced TA solubility (2619.7 ± 57.6 μg/g). The optimized MEG demonstrated temperature-dependent gelation with a gelation time of 208 ± 10 sec at 37 °C. Slow degradation of the gel matrix sustained release of TA from MEG compared to the ME formulation. Both TA-ME and TA-MEG were found to be nontoxic to NIH3T3 cells at the test concentrations (0 to 5 µg/mL), and biocompatible after intratympanic administration to mice. The incorporation of ME into thermosensitive hydrogels prolonged retention of TA at the site of administration until 6 days. As a consequence, the enhanced drug absorption into the cochlea in TA-MEG group (approximately 2 times higher than other groups) protected hair cells, spiral ganglion neurons, and stria vascular cells from cisplatin-induced damage. Therefore, this injectable TA-loaded MEG is an effective and safe vehicle for the sustained delivery of triamcinolone acetonide into the inner ear.

Tackling acne vulgaris by fabrication of tazarotene-loaded essential oil-based microemulsion: In vitro and in vivo evaluation

This study aimed to formulate and optimize an anti-acne drug namely tazarotene (TZR) in essential oil-based microemulsion (ME) using either Jasmine oil (Jas) or Jojoba oil (Joj). TZR-MEs were prepared using two experimental designs (Simplex Lattice Design®) and characterized for droplet size, polydispersity index, and viscosity. Further in vitro, ex vivo, and in vivo investigations were performed for the selected formulations. Results revealed that TZR-selected MEs exhibited suitable droplet size, homogenous dispersions, and acceptable viscosity, in addition to spherical-shaped particles in morphology. The ex vivo skin deposition study showed a significant TZR accumulation in all skin layers for the Jas-selected ME over the Joj one. Further, TZR didn't show any antimicrobial activity against P. acnes, however, it was boosted when it was incorporated into the selected MEs. The in vivo study results of the infected mice ears induced by P. acnes revealed that our selected MEs successfully reached a high level of ear thickness reduction of 67.1% and 47.4% for Jas and Joj selected MEs, respectively, versus only 4% for the market product. Finally, the findings confirmed the ability to use essential oil-based ME, particularly with Jas, as a promising carrier for topical TZR delivery in the treatment of acne vulgaris.

Self-Emulsifying Drug Delivery Systems (SEDDS) Containing Reverse Micelles: Advanced Oral Formulations for Therapeutic Peptides

Alternative methods to hydrophobic ion pairing for the formation of lipophilic complexes of peptide drugs to incorporate them in lipid-based nanocarriers such as self-emulsifying drug delivery systems (SEDDS) for oral administration are highly on demand. Such an alternative might be reverse micelles. Within this study, SEDDS containing dry reverse micelles (dRMsPMB ) formed with an anionic (sodium docusate; AOT), cationic (dimethyl-dioctadecyl-ammonium bromide; DODAB), amphoteric (soy lecithin; SL), or non-ionic (polysorbate 85; P85) surfactant loaded with the model peptide drug polymyxin B (PMB) are developed. They are characterized regarding size, payload, release kinetics, cellular uptake, and peptide activity. SEDDS exhibit sizes from 22.2 ± 1.7 (AOT-SEDDS-dRMsPMB ) to 61.7 ± 3.2 nm (P85-SEDDS-dRMsPMB ) with payloads up to 2% that are approximately sevenfold higher than those obtained via hydrophobic ion pairing. Within 6 h P85-SEDDS-dRMsPMB and AOT-SEDDS-dRMsPMB show no release of PMB in aqueous medium, whereas DODAB-SEDDS-dRMsPMB and SL-SEDDS-dRMsPMB show a sustained release. DODAB-SEDDS-dRMsPMB improves uptake by Caco-2 cells most efficiently reaching even ≈100% within 4 h followed by AOT-SEDDS-dRMsPMB with ≈20% and P85-/SL-SEDDS-dRMsPMB with ≈5%. The peptide drug maintains its antimicrobial activity in all SEDDS-dRMsPMB . According to these results, SEDDS containing dRMs might be a game changing strategy for oral peptide drug delivery.

Current challenges ahead in preparation, characterization, and pharmaceutical applications of nanoemulsions

Nanoemulsions (NEs) are emulsions with particle size of less than around 100 nm. Reviewing the literature, several reports are available on NEs, including preparation, characterization, and applications of them. This review aims to brief challenges that researchers or formulators may encounter when working with NEs. For instance, when selecting NE components and identifying their concentrations, stability and safety of the preparation should be evaluated. When preparing an NE, issues over scale-up of the preparation as well as possible effects of the preparation process on the active ingredient need to be considered. When characterizing the NEs, the two major concerns are accuracy of the method and accessibility of the characterizing instrument. Also a highly efficient NE for clinical use to deliver the active ingredient to the target tissue with maximum safety profile is commonly sought. Throughout the review we also have tried to suggest approaches to overcome the challenges. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Comparative studies on the aggregate formation of synthesized zwitterionic gemini and monomeric surfactants in the presence of the amphiphilic antipsychotic drug chlorpromazine hydrochloride in aqueous solution: an experimental and theoretical approach

The formation of aggregates, which are widely used in the field of biochemistry and the medical industry, was studied with different compositions of alkyl betaine gemini surfactant (C14Ab) in conjugation with chlorpromazine hydrochloride (CPZ). The results were compared with those of a single-chain zwitterionic surfactant (C12DmCB) of the same type with CPZ. Dynamic light scattering (DLS), confocal laser scanning microscopy (CLSM), and transmission electron microscopy (TEM) methods were used to distinguish the aggregates for the CPZ/C14Ab system in aqueous solutions above a certain mole fraction of the drug CPZ (αCPZ = 0.2). Time-resolved fluorescence decay measurements of acridine orange revealed relative polarity near the head group regions of mixed micelle (CPZ/C14Ab and CPZ/C12DmCB) systems. The hydrophilic environment around the head group regions of the CPZ/C14Ab system was different from that in the case of the CPZ/C12DmCB system. On the other hand, several theoretical models were employed (Clint, Rubingh, Motomura, and SPB) for mixed micellar systems to elucidate the different interaction parameters. Such a systematic study of a zwitterionic gemini amphiphile and its interaction with other amphiphiles and an amphiphilic drug molecule is rare in the literature.

High-Performance Nanogel-in-Oils as Emulsion Evolution Controller for Displacement Enhancement in Porous Media

We designed and synthesized high-performance nanogel-in-oils with intermediate properties between solid particles and liquid droplets for multiphase flow control in porous media. The ultrasmall polymeric nanogels prepared via inverse emulsion polymerization were efficiently encapsulated in micrometer-sized oil droplets with the aid of surfactants during transfer from the oil phase to the aqueous phase. The composite colloidal system exhibited high loading capacity, unimodal size distribution, and long-term kinetic stability in suspension. The colloidal behaviors of nanogel-in-oils and the corresponding interfacial evolution during displacement in porous media were investigated via microfluidic experiments. In situ emulsification was observed with a state contrary to that of static characterizations. The spontaneous and sustainable formation of foam-like water-in-oil macroemulsions originated from aqueous phase breakup and oil film development, both enhanced by nanogel-in-oils. Sweeping efficiency enhancement by invasion events and residual oil transport in macroemulsion phases yielded exceptional displacement performances. Flow field fluctuations and emulsion state variations can be manipulated by adjusting nanogel-in-oil concentrations. The nanogel-in-oil suspension was found to exhibit optimal performance among the tested dispersed systems.

Celecoxib Oral Solution and the Benefits of Self-Microemulsifying Drug Delivery Systems (SMEDDS) Technology: A Narrative Review

INTRODUCTION

The oral route of drug delivery is the most widespread and preferred route of administration, but it has several limitations, including variable pharmacokinetics (PK), reduced dissolution and absorption, and gastrointestinal irritation. Further, many compounds have low aqueous solubility, which also limits intestinal absorption.

METHODS

For this narrative review, we conducted a literature search of PubMed until August 2022, focusing on emulsions, microemulsions, nanoemulsions, and self-emulsifying drug delivery systems.

RESULTS

The self-microemulsifying drug delivery system (SMEDDS) overcomes these limitations of hydrophobic compounds to enhance their bioavailability. A SMEDDS formulation is a clear, thermodynamically stable, oil-in-water emulsion of lipid, solubilized drug, and two surfactants, which spontaneously forms droplets < 100 nm in diameter. These components help deliver presolubilized drugs to the gastrointestinal tract, while protecting them from degradation in gastric acid or first-pass hepatic metabolism. SMEDDS formulations have improved oral drug delivery in the treatment of cancer (paclitaxel), viral infections (ritonavir), and migraine headache (ibuprofen and celecoxib oral solution). The American Headache Society recently updated their consensus statement for the acute treatment of migraine and included a selective cyclo-oxygenase-2 selective inhibitor formulated in SMEDDS, celecoxib oral solution. This SMEDDS formulation showed pronounced improvement in bioavailability compared with celecoxib capsules, allowing for a low dose of celecoxib in the oral solution to provide safe and effective acute migraine treatment. Here, we will focus on SMEDDS formulations, what differentiates them from other analogous emulsions as vehicles for poorly soluble drugs, and their clinical application in the acute treatment of migraine.

CONCLUSIONS

Oral drugs reformulated in SMEDDS have shown accelerated times to peak plasma drug concentrations and increased maximum plasma concentrations, compared with capsules, tablets, or suspensions. SMEDDS technology increases both drug absorption and bioavailability of lipophilic drugs, compared with other formulations. Clinically, this allows the use of lower doses with improved PK profiles without compromising efficacy, as shown with celecoxib oral solution for the acute treatment of migraine.

A study on the preparation conditions of lidocaine microemulsion based on multi-objective genetic algorithm

Background: Topical lidocaine microemulsion preparations with low toxicity, low irritation, strong transdermal capability and convenient administration are urgently needed. Methods: Box-Behnken design was performed for three preparation conditions of 5% lidocaine microemulsions: mass ratio of the mass ratio of surfactant/(oil phase + surfactant) (X1), the mass ratio of olive oil/(α-linolenic acid + linoleic acid) (X2) and the water content W% (X3). Then, five multi-objective genetic algorithms were used to optimize the three evaluation indices to optimize the effects of lidocaine microemulsion preparations. Finally, the ideal optimization scheme was experimentally verified. Results: Non-dominated Sorting Genetic Algorithm-II was used for 30 random searches. Among these, Scheme 2: X1 = 0.75, X2 = 0.35, X3 = 75%, which resulted in Y1 = 0.17 μg/(cm2·s) and Y2 = 0.74 mg/cm2; and the Scheme 19: X1 = 0.68, X2 = 1.42, X3 = 75% which resulted in Y1 = 0.14 μg/(cm2·s) and Y2 = 0.80 mg/cm2, provided the best matches for the objective function requirements. The maximum and average fitness of the method have reached stability after 3 generations of evolution. Experimental verification of the above two schemes showed that there were no statistically significant differences between the measured values of Y1 and Y2 and the predicted values obtained by optimization (p > 0.05) and are close to the target value. Conclusion: Two lidocaine microemulsion preparation protocols were proposed in this study. These preparations resulted in good transdermal performance or long anesthesia duration, respectively.

Crisaborole loaded nanoemulgel for the mitigation of atopic dermatitis in mice model

OBJECTIVE

The present work aims to formulate nanoemulgel of crisaborole (CB) and evaluate its effectiveness against 2,4-Di-nitrochlorobenzene induced (DNCB) atopic dermatitis (AD) in mice.

SIGNIFICANCE

AD is a chronic inflammation of the skin affecting the quality of life. CB is a topical PDE4 inhibitor marketed as a 2% ointment. It, however, possesses poor aqueous solubility. An o/w nanoemulsion shall exhibit an enhanced therapeutic effect owing to the increased solubility of CB and an augmented skin penetration. The addition of a gelling agent to form a nanoemulgel further provides ease of application to the patients.

METHODS

Nanoemulsion was prepared by aqueous titration method using caproyl PGMC, cremophore EL and propylene glycol as the oil, surfactant, and cosurfactant respectively. The formulations were characterized by their size, zeta potential and polydispersity index (PDI). 1% Carbopol 934 was used as the gelling agent to formulate nanoemulgel comprising of optimized nanoemulsion (NE 9). Ex vivo skin permeation of the CB nanoemulgel was compared with the CB ointment. Its therapeutic effect was evaluated in Balb/c mice.

RESULTS

NE 9 comprised of 7.49% oil, 37.45% Smix (1:3) and water 55.06%. Its particle size, PDI and zeta potential were 15.45 ± 5.265 nm, 0.098 and -17.9 ± 8.00 mV respectively. The nanoemulgel exhibited a 3-fold higher permeation flux as compared to the ointment. In vivo studies demonstrated that the nanoemulgel provided better therapeutic effect than the ointment.

CONCLUSION

We can thereby conclude that nanoemulgel formulation can be a successful drug delivery strategy for enhancing the therapeutic effect of CB.

Topical Microemulsions: Skin Irritation Potential and Anti-Inflammatory Effects of Herbal Substances

Microemulsions (MEs) have gained prominence as effective drug delivery systems owing to their optical transparency, low viscosity, and thermodynamic stability. MEs, when stabilized with surfactants and/or co-surfactants, exhibit enhanced drug solubilization, prolonged shelf life, and simple preparation methods. This review examines the various types of MEs, explores different preparation techniques, and investigates characterization approaches. Plant extracts and bioactive compounds are well established for their utilization as active ingredients in the pharmaceutical and cosmetic industries. Being derived from natural sources, they serve as preferable alternatives to synthetic chemicals. Furthermore, they have demonstrated a wide range of therapeutic effects, including anti-inflammatory, antimicrobial, and antioxidant activities. However, the topical application of plant extracts and bioactive compounds has certain limitations, such as low skin absorption and stability. To overcome these challenges, the utilization of MEs enables enhanced skin absorption, thereby making them a valuable mode of administration. However, considering the significant surfactant content in MEs, this review evaluates the potential skin irritation caused by MEs containing herbal substances. Additionally, the review explores the topical application of MEs specifically for herbal substances, with an emphasis on their anti-inflammatory properties.

Novel wine in an old bottle: Preventive and therapeutic potentials of andrographolide in atherosclerotic cardiovascular diseases

Atherosclerotic cardiovascular disease (ASCVD) frequently results in sudden death and poses a serious threat to public health worldwide. The drugs approved for the prevention and treatment of ASCVD are usually used in combination but are inefficient owing to their side effects and single therapeutic targets. Therefore, the use of natural products in developing drugs for the prevention and treatment of ASCVD has received great scholarly attention. Andrographolide (AG) is a diterpenoid lactone compound extracted from Andrographis paniculata. In addition to its use in conditions such as sore throat, AG can be used to prevent and treat ASCVD. It is different from drugs that are commonly used in the prevention and treatment of ASCVD and can not only treat obesity, diabetes, hyperlipidaemia and ASCVD but also inhibit the pathological process of atherosclerosis (AS) including lipid accumulation, inflammation, oxidative stress and cellular abnormalities by regulating various targets and pathways. However, the pharmacological mechanisms of AG underlying the prevention and treatment of ASCVD have not been corroborated, which may hinder its clinical development and application. Therefore, this review summarizes the physiological and pathological mechanisms underlying the development of ASCVD and the in vivo and in vitro pharmacological effects of AG on the relative risk factors of AS and ASCVD. The findings support the use of the old pharmacological compound ('old bottle') as a novel drug ('novel wine') for the prevention and treatment of ASCVD. Additionally, this review summarizes studies on the availability as well as pharmaceutical and pharmacokinetic properties of AG, aiming to provide more information regarding the clinical application and further research and development of AG.

Improvement in Skin Penetration Capacity of Linalool by Using Microemulsion as a Delivery Carrier: Formulation Optimization and In Vitro Evaluation

Linalool is an aromatic oil with analgesic, anti-inflammatory and anti-UVB-induced skin damage effects. The aim of this study was to develop a linalool-loaded microemulsion formulation for topical application. In order to quickly obtain an optimal drug-loaded formulation, statistical tools of the response surface methodology and a mixed experimental design with four independent variables of oil (X₁), mixed surfactant (X₂), cosurfactant (X₃) and water (X₄) were used to design a series of model formulations in order to analyze the effect of the composition on the characteristics and permeation capacity of linalool-loaded microemulsion formulations and to obtain an appropriate drug-loaded formulation. The results showed that the droplet size, viscosity and penetration capacity of linalool-loaded formulations were significantly affected by formulation component proportions. The skin deposition amount of the drug and flux of such formulations expressively increased about 6.1-fold and 6.5-fold, respectively, when compared to the control group (5% linalool dissolved in ethanol). After 3 months of storage, the physicochemical characteristics and drug level did not show a significant change. The linalool formulation-treated rat skin showed non-significant irritation compared to skin treatments in the distilled-water-treated group. The results showed that specific microemulsion applications might be considered as potential drug delivery carriers for essential oil topical application.

Investigation of Nanostructure and Interactions in Water-in-Xylene Microemulsions Using Small-Angle X-ray and Neutron Scattering

The ability to modulate the size, the nanostructure, and the macroscopic properties of water-in-oil microemulsions is useful for a variety of technological scenarios. To date, diverse structures of water-in-alkane microemulsions stabilized by sodium bis(2-ethylhexyl) sulfosuccinate (AOT) have been extensively studied. Even though the decisive parameter which dictates the phase behavior of micremulsions is the nature of the continuous phase, relatively very few reports are available on the structure and interactions in the microemulsions of aromatic oil. Here, we present a fundamental investigation on water-in-xylene microemulsions using small-angle neutron scattering (SANS) at a fixed molar ratio (ω) of water to AOT. We elucidate the microstructural changes in the water-AOT-xylene ternary system at dilute volume fractions (Φ = 0.005, 0.01, 0.03), where the droplet-droplet interactions are absent, to moderately concentrated systems (Φ = 0.05, 0.10, 0.15, and 0.20), where colloidal interactions become important. We also characterize the reverse microemulsions (RMs) for thermally induced microstructural changes at six different temperatures from 20 to 50 °C. Depending on the magnitude of Φ, the scattering data is found to be well described by considering the RMs as a dispersion of droplets (with a Schulz polydispersity) which interact as sticky hard spheres. We show that while the droplet diameter remains almost constant with increase in the volume fraction, the attractive interactions become prominent, much like the trends observed for water-in-alkane microemulsions. With increase in temperature, the RMs showed a marginal decrease in the droplet size but no pronounced dependence on the interactions was observed with the overall structure remaining intact. The fundamental study on a model system presented in this work is key to understanding the phase behavior of multiple component microemulsions as well as their design for applications at higher temperatures, where the structure of most RMs breaks down.

Solid microemulsion preconcentrates on pH responsive metal-organic framework for tableting

Poorly water-soluble drugs are frequently formulated with lipid-based formulations including microemulsions and their preconcentrates. We detailed the solidification of drug-loaded microemulsion preconcentrates with the acid-sensitive metal-organic framework ZIF-8 by X-ray powder diffraction and solid-state nuclear magnetic resonance spectroscopy. Adsorption and desorption dynamics were analyzed by fluorescence measurement, high-performance liquid chromatography, dynamic light scattering and ¹H-DOSY experiments using the model compounds Nile Red, Vitamin K₁, and Lumefantrine. Preconcentrates and drugs were successfully loaded onto ZIF-8 while preserving its crystal structure. The solid powder was pressable to tablets or 3D-printed into oral dosage forms. At low pH, colloidal solutions readily formed, solubilizing the poorly water-soluble compounds. The use of stimuli-responsive metal organic frameworks as carriers for the oral delivery of lipid-based formulations points towards solid dosage forms readily forming colloidal microemulsions.

Science of, and insights into, thermodynamic principles for dermal formulations

Studies have demonstrated the significant role of the thermodynamic activity of drugs in skin drug delivery. This thermodynamic activity works as a driving force for increasing/improving the absorption of drugs by the skin. It can be changed according to the physicochemical parameters (e.g., solubility, partition coefficient, and water activity) of the drug in the vehicle. Thermodynamic principles have been used for the development of novel topical and transdermal delivery systems, demonstrating the importance of thermodynamic activity in enhancing drug permeation through the skin. In this review, we provide insights into thermodynamic principles and their roles in optimizing topical and transdermal drug delivery systems.

Nanosized Drug Delivery Systems to Fight Tuberculosis

Tuberculosis (TB) is currently the second deadliest infectious disease. Existing antitubercular therapies are long, complex, and have severe side effects that result in low patient compliance. In this context, nanosized drug delivery systems (DDSs) have the potential to optimize the treatment's efficiency while reducing its toxicity. Hundreds of publications illustrate the growing interest in this field. In this review, the main challenges related to the use of drug nanocarriers to fight TB are overviewed. Relevant publications regarding DDSs for the treatment of TB are classified according to the encapsulated drugs, from first-line to second-line drugs. The physicochemical and biological properties of the investigated formulations are listed. DDSs could simultaneously (i) optimize the therapy's antibacterial effects; (ii) reduce the doses; (iii) reduce the posology; (iv) diminish the toxicity; and as a global result, (v) mitigate the emergence of resistant strains. Moreover, we highlight that host-directed therapy using nanoparticles (NPs) is a recent promising trend. Although the research on nanosized DDSs for TB treatment is expanding, clinical applications have yet to be developed. Most studies are only dedicated to the development of new formulations, without the in vivo proof of concept. In the near future, it is expected that NPs prepared by "green" scalable methods, with intrinsic antibacterial properties and capable of co-encapsulating synergistic drugs, may find applications to fight TB.

Curcumin-loaded microemulsion: formulation, characterization, and in vitro skin penetration

OBJECTIVE

Formulation of curcumin in a microemulsion with a high loading capacity and that favors its penetration into the skin.

SIGNIFICANCE

Take advantage of the properties of microemulsions to promote the penetration of curcumin into the skin, with the aim of enhancing its therapeutic effects.

METHODS

Curcumin was formulated in microemulsions based on oleic acid (oil phase), Tween® 80 (surfactant), and Transcutol^® HP (cosurfactant). The microemulsion formation area was mapped by constructing pseudo-ternary diagrams for surfactant:co-surfactant ratios 1:1, 1:2, and 2:1. Microemulsions were characterized through measurements of specific weight, refractive index, conductivity, viscosity, droplet size, and in vitro skin permeation studies.

RESULTS

Nine microemulsions were prepared and characterized, showing clear, stable formulations with globule size dependent on the proportion of the components. The microemulsion with the highest loading capacity (60 mg/mL), based on Tween^® 80, Transcutol^® HP, oleic acid, and water (40:40:10:10) was able to penetrate the viable epidermis, finding a total amount of curcumin in the receptor medium at 24 h of 10.17 ± 9.7 µg/cm². The distribution of curcumin in the skin, visualized by confocal laser scanning microscopy, showed that the maximum amount was located between 20 and 30 µm.

CONCLUSION

The inclusion of curcumin in a microemulsion allows its passage into and through the skin. The localization of curcumin, especially in the viable epidermis, would be important for those cases where local conditions are sought to be treated.

Formulation of Aucklandiae Radix Extract-Loaded Nanoemulsions and Its Characterization and Evaluations In Vitro and In Vivo

This study aimed to screen, design, and evaluate an optimal nanoemulsion formulation for Aucklandiae Radix extraction (ARE). A simple lattice design (SLD) method was used to determine the preparation process of Aucklandiae Radix extract-nanoemulsions (ARE-NEs). After optimization, the average particle size of ARE-NEs was 14.1 ± 1.1 nm, polydispersity index was 0.2376, and pH was 6.92. In vitro penetration tests verified that the permeability ratios of costunolide (CE), dehydrocostus lactone (DE), and ARE-NEs were approximately 6.33 times and 8.20 times higher, respectively, than those of the control group. The results of the pharmacokinetic study indicated that after topical administration, the content of the index components of ARE-NEs increased in vivo, with a longer release time and higher bioavailability in vivo than in vitro. The index components were CE and DE, respectively. In addition, a skin irritation test was conducted on normal and skin-damaged rabbits, aided by HE staining and scanning electron microscopy, to reveal the transdermal mechanism of ARE-NEs and proved that NEs are safe for topical application. ARE-NEs energetically developed the properties of skin and penetration through the transdermal route, which were secure when applied via the transdermal delivery system .

The Therapeutic Application of Tamarix aphylla Extract Loaded Nanoemulsion Cream for Acid-Burn Wound Healing and Skin Regeneration

Background and Objectives: Nanomedicine is a constantly growing field for the diagnosis and treatment of various diseases as well as for regenerative therapy. Nanotechnology-based drug-delivery systems improve pharmacological and pharmacokinetic profiles of plants based biologically active molecules. Based on traditional claims, leaves of the Tamarix aphylla (TA) were investigated for their potential healing activity on burn wounds. Materials and Methods: In this study, TA-based nanoemulsion was prepared. The nanoemulsion was characterized for size, zeta potential, pH, viscosity, and stability. The nanoemulsion containing plant extract was converted into cream and evaluated for its efficacy against acid-burn wounds inflicted in the dorsum of rabbits. The animals were classified into four main groups: Group A as a normal control group, Group B as a positive control (treated with cream base + silver sulfadiazine), Group C as a standard drug (silver sulfadiazine), and Group D as a tested (treated with nanoemulsion cream containing TA extract). The prepared system could deliver TA to the target site and was able to produce pharmacological effects. On days 0, 7, 14, 21, 28, and 35, wound contraction rate was used to determine healing efficacy. The wound samples were collected from the skin for histological examination. Results: Based on statistical analysis using wound-healing time, Group D showed a shorter period (21.60 ± 0.5098) (p < 0.01) than the average healing time of Group C (27.40 ± 0.6002) (p < 0.05) and Group B (33.40 ± 0.8126) (p < 0.05). The histopathological assessment showed that burn healing was better in Group D compared with Group C and Group B. The nanoemulsion cream had a non-sticky texture, low viscosity, excellent skin sensations, and a porous structure. By forming a protective layer on the skin and improving moisture, it enhanced the condition of burnt skin. Conclusions: According to the findings of this study, nanoemulsion cream containing TA extract has great potential in healing acid-burn wounds