Development of a novel microemulsion for oral absorption enhancement of all-trans retinoic acid

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.

Simplex Lattice Design and Machine Learning Methods for the Optimization of Novel Microemulsion Systems to Enhance p-Coumaric Acid Oral Bioavailability: In Vitro and In Vivo Studies

Novel p-coumaric acid microemulsion systems were developed to circumvent its absorption and bioavailability challenges. Simplex-lattice mixture design and machine learning methods were employed for optimization. Two optimized formulations were characterized using in vitro re-dispersibility and cytotoxicity on various tumor cell lines (MCF-7, CaCO2, and HepG2). The in vivo bioavailability profiles of the drug loaded in the two microemulsion systems and in the suspension form were compared. The optimized microemulsions composed of Labrafil M1944 CS (5.67%)/Tween 80 (38.71%)/Labrasol (38.71%)/water (16.92%) and Capryol 90 (0.50%)/Transcutol P (26.67%)/Tween 80 (26.67%)/Labrasol (26.67%)/water (19.50%), respectively. They revealed uniform and stable p-coumaric acid-loaded microemulsion systems with a droplet size diameter of about 10 nm. The loaded microemulsion formulations enhanced the drug re-dispersibility in contrast to the drug suspension which exhibited 5 min lag time. The loaded formulae were significantly more cytotoxic on all cell lines by 11.98-16.56 folds on MCF-7 and CaCo2 cells and 47.82-98.79 folds on HepG2 cells higher than the pure drug. The optimized microemulsions were 1.5-1.8 times more bioavailable than the drug suspension. The developed p-coumaric acid microemulsion systems could be considered a successful remedy for diverse types of cancer.

Novel Microemulsion Containing Benzocaine and Fusidic Acid Simultaneously: Formulation, Characterization, and In Vitro Evaluation for Wound Healing

Modern drug carrier technologies, such as microemulsions with small droplet sizes and high surface areas, improve the ability of low water solubility active ingredients to permeate and localize. The goal of this study was to create microemulsion formulations for wound healing that contained both fusidic acid (FA), an antibacterial agent, and benzocaine (BNZ), a local anesthetic. Studies on characterization were carried out, including viscosity, droplet size, and zeta potential. The drug-loaded microemulsion had a stable structure with -3.014 ± 1.265 mV of zeta potential and 19.388 ± 0.480 nm of droplet size. In both in vitro release and ex vivo permeability studies, the microemulsion was compared with Fucidin cream and oily BNZ solution. According to the drug release studies, BNZ release from the microemulsion and the BNZ solution showed a similar profile (p > 0.05), while FA release from the microemulsion had a higher drug release compared to Fucidin cream (p < 0.001). The microemulsion presented lower drug permeation (p > 0.05) for both active ingredients, on the other hand, provided higher drug accumulation compared to the control preparations. Moreover, according to the results of in vitro wound healing activity, the microemulsion indicated a dose-dependent wound healing potential with the highest wound healing activity at the highest concentrations. To the best of our knowledge, this developed BNZ- and FA-loaded microemulsion would be a promising candidate to create new opportunities for wound healing thanks to present the active ingredients, which have low water solubility, in a single formulation and achieved higher accumulation than control preparations.

Xanthan and gum acacia modified olive oil based nanoemulsion as a controlled delivery vehicle for topical formulations

In this study, olive oil nanoemulsion modified with xanthan gum and gum acacia was explored as a potential controlled topical delivery vehicle. Oil-in-water nanoemulsion formulated with optimized composition of olive oil, tween 80, and water was used as the drug carrier and further modified with gum. Effect of gum on nanoemulsion different physiochemical characteristics, stability, rheology, drug release and encapsulation efficiency were investigated. Results showed that developed nanoemulsion behaved as low viscosity Newtonian fluid and released 100 % drug within 6 h. Modification with xanthan and gum acacia had significantly improved formulation viscosity, drug encapsulation efficiency (>85 %) and controlled drug release up to 40 % with release pattern following Korsmeyer-Peppas model. Additionally, xanthan gum modified formulation exhibited shear thinning rheology by forming an extended network in the continuous phase, whereas gum acacia modified formulation behaved as Newtonian fluid at high shear rate (>200 s-1). Furthermore, xanthan gum modified formulations had improved zeta potential, stability, monodispersity, and hemocompatibility and showed high antibacterial activity against S. aureus than gum acacia modified formulations. These results indicate the higher potential of xanthan gum modified formulation as a topical delivery vehicle. Moreover, skin irritation test demonstrated the safety of developed formulations for topical application.

Sustained release gel (polymer-free) of itraconazole-loaded microemulsion for oral candidiasis treatment: time-kill kinetics and cellular uptake

Itraconazole (ICZ) was prepared in a self-microemulsifying (SM) gel. This gel was intended for use in the oral mucosa, where low volume and flow of saliva result in limited solubility and absorption of drugs that are poorly water-soluble. The drug-loaded gel formulation (ICZ-SM) was selected as a clear solution in the ternary phase diagram to improve the solubility of ICZ. Seven ratios (S1-S7) were prepared by mixing polyoxyl 35 castor oils (P35), a medium chain with a blend of mono-, di-, and triglycerides (MCT), and water. Phase separation of large-sized emulsions by countering with artificial saliva were observed in dilution tests for the formulation contained MCT, P35, and water at the ratios of 70:20:10 (S1), 10:80:10 (S3), and 20:60:20 (S4). Formulations in the ratios of 15:50:35 (S5) and 19:43:38 (S6) produced strong ICZ-SM gels, as shown by rheology tests, whereas the formulations at the ratios of 30:60:10 (S2) and 10:43:47 (S7) exhibited no elasticity. A model of zero-order kinetic (S5) and first-order kinetic (S6) were found to best fit the release kinetics of ICZ from the gels. Time-killing assays revealed that S5 and S6 required less time compared with S2 and the ICZ solution. Furthermore, S5 exhibited the highest increase in cell uptake compared with S2, S6, and the ICZ solution. These findings suggest that the ICZ-SM gel was a free polymer capable of delivering an ICZ for the treatment of oral candidiasis, and that ICZ-SM gels applied locally exhibit enhanced absorption into cells.

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.

Oral administration of Huanglian-Houpo herbal nanoemulsion loading multiple phytochemicals for ulcerative colitis therapy in mice

How to achieve stable co-delivery of multiple phytochemicals is a common problem. This study focuses on the development, optimization and characterization of Huanglian-HouPo extract nanoemulsion (HLHPEN), with multiple components co-delivery, to enhance the anti-ulcerative colitis (UC) effects. The formulation of HLHPEN was optimized by pseudo-ternary phase diagram combined with Box-Behnken design. The physicochemical properties of HLHPEN were characterized, and its anti-UC activity was evaluated in DSS-induced UC mice model. Based on preparation process optimization, the herbal nanoemulsion HLHPEN was obtained, with the droplet size, PDI value, encapsulation efficiency (EE) for 6 phytochemicals (berberine, epiberberine, coptisine, bamatine, magnolol and honokiol) of 65.21 ± 0.82 nm, 0.182 ± 0.016, and 90.71 ± 0.21%, respectively. The TEM morphology of HLHPEN shows the nearly spheroidal shape of particles. The optimized HLHPEN showed a brownish yellow milky single-phase and optimal physical stability at 25 °C for 90 days. HLHPEN exhibited the good particle stability and gradual release of phytochemicals in SGF and SIF, to resist the destruction of simulated stomach and small intestine environment. Importantly, the oral administration of HLHPEN significantly restored the shrunk colon tissue length and reduced body weight, ameliorated DAI value and colon histological pathology, decreased the levels of inflammatory factors in DSS-induced UC mice model. These results demonstrated that HLHPEN had a significant therapeutic effect on DSS-induced UC mice, as a potential alternative UC therapeutic agent.

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.

Propranolol-Loaded Limonene-Based Microemulsion Thermo-Responsive Mucoadhesive Nasal Nanogel: Design, In Vitro Assessment, Ex Vivo Permeation, and Brain Biodistribution

Propranolol is the first-line drug for managing migraine attacks. D-limonene is a citrus oil known for its neuroprotective mechanism. Thus, the current work aims to design a thermo-responsive intranasal limonene-based microemulsion mucoadhesive nanogel to improve propranolol efficacy. Microemulsion was fabricated using limonene and Gelucire^® as the oily phase, Labrasol^®, Labrafil^®, and deionized water as the aqueous phase, and was characterized regarding its physicochemical features. The microemulsion was loaded in thermo-responsive nanogel and evaluated regarding its physical and chemical properties, in vitro release, and ex vivo permeability through sheep nasal tissues. Its safety profile was assessed via histopathological examination, and its capability to deliver propranolol effectively to rats' brains was examined using brain biodistribution analysis. Limonene-based microemulsion was of 133.7 ± 0.513 nm diametric size with unimodal size distribution and spheroidal shape. The nanogel showed ideal characteristics with good mucoadhesive properties and in vitro controlled release with 1.43-fold enhancement in ex vivo nasal permeability compared with the control gel. Furthermore, it displayed a safe profile as elucidated by the nasal histopathological features. The nanogel was able to improve propranolol brain availability with C_max 970.3 ± 43.94 ng/g significantly higher than the control group (277.7 ± 29.71 ng/g) and with 382.4 % relative central availability, which confirms its potential for migraine management.

Optimization of Delivery and Bioavailability of Encapsulated Caffeic Acid

Caffeic acid is a widely distributed phenolic acid. It is described in the scientific literature that caffeic acid has poor solubility. The aim of this study was to improve the solubility of caffeic acid for better dissolution kinetics when administered orally. During the study, oral capsules of different compositions were modeled. The results of the disintegration test revealed that the excipients affected the disintegration time of the capsules. The excipient hypromellose prolonged the disintegration time and dissolution time of caffeic acid. The dissolution kinetics of caffeic acid from capsules depend on the chosen excipients. P407 was more effective compared to other excipients and positively affected the dissolution kinetics of caffeic acid compared to other excipients. When the capsule contained 25 mg of β-cyclodextrin, 85% of the caffeic acid was released after 60 min. When the capsule contained 25-50 mg poloxamer 407, more than 85.0% of the caffeic acid was released from capsules after 30 min. The research results showed that in order to improve the dissolution kinetics of caffeic acid, one of the important steps is to improve its solubility.

Itraconazole-loaded microemulsions: formulation, characterization, and dermal delivery using shed snakeskin as the model membrane

Microemulsions (MEs) were developed for dermal delivery of 1% w/w itraconazole (ITZ). Solubility of ITZ in various oils was investigated and clove oil was selected as oil phase. Pseudoternary phase diagrams were constructed by titration method. The system containing clove oil as oil phase, Tween^®80 as surfactant, and 1:1 mixture of water and polyethylene glycol 400 as aqueous phase provided the largest ME region. It was selected for the formulation development of ITZ-loaded MEs. Physicochemical stability was evaluated at 4 °C, room temperature (25 °C), and 45 °C for three months. In vitro permeation and retention studies were assessed using shed snakeskin as a model membrane. Antifungal activity was investigated by agar diffusion method. Results indicated that incorporation of ITZ in the selected MEs did not affect physical properties. Physicochemical data after storage periods revealed that the most suitable storage temperature was 4 °C. Skin permeation and retention data indicated that water-in-oil (w/o) ITZ-loaded MEs had superior dermal delivery of ITZ than oil-in-water (o/w) ITZ-loaded ME and ITZ-oily solution. Moreover, w/o ITZ-loaded MEs showed larger inhibition zones against C. albicans and T. rubrum than a commercial gel. Therefore, w/o ITZ-loaded MEs possibly provided effective dermal delivery and antifungal activity to treat superficial fungal infections.

The Development and Evaluation of Phase Transition Microemulsion for Ocular Delivery of Acetazolamide for Glaucoma Treatment

The aim of this study was to develop microemulsion (ME) formulation with possible phase transition into liquid crystals upon ocular application to enhance acetazolamide bioavailability. Pseudoternary phase diagrams were constructed using olive oil or castor oil (oily phase), Tween 80 (surfactant), and sodium carbonate solution (aqueous phase). Microemulsion and liquid crystal (LC) formulations were selected from the constructed phase diagrams and were evaluated for rheological properties and in vitro drug release. The efficacy of the developed formulations in reducing intraocular pressure (IOP) was assessed in vivo. In vitro release study showed slower release rate from LC and ME compared with drug solution with the release from LC being the slowest. Ocular application of acetazolamide ME formulations or aqueous solution resulted in significant reduction in IOP from baseline. The recorded T_max values indicated faster onset of action for acetazolamide aqueous solution (1 h) compared with ME systems (3 h). However, the duration of action was prolonged and the reduction in IOP continued for up to 10 h in case of MEs, while that of aqueous solution was only for 4-5 h. The study suggested ME formulations for ocular delivery of acetazolamide with enhanced efficacy and prolonged duration of action.

Dissolution Improvement of Progesterone and Testosterone via Impregnation on Mesoporous Silica Using Supercritical Carbon Dioxide

Progesterone (PRG) and testosterone (TST) were impregnated on mesoporous silica (ExP) particles via supercritical carbon dioxide (scCO2) processing at various pressures (10–18 MPa), temperatures (308.2–328.2 K), and time (30–360 min). The impact of a co-solvent on the impregnation was also studied at the best determined pressure and temperature. The properties of the drug embedded in silica particles were analysed via gas chromatography (GC), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and nitrogen adsorption. An impregnation of 1 to 82 mg/g for PRG and 0.1 to 16 mg/g for TST was obtained depending on the processing parameters. There was a significant effect of pressure, time, and co-solvent on the impregnation efficiency. Generally, an increase in time and pressure plus the use of co-solvent led to an improvement in drug adsorption. Conversely, a rise in temperature resulted in lower impregnation of both TST and PRG on ExP. There was a substantial increase in the dissolution rate (> 90% drug release within the first 2 min) of both TST and PRG impregnated in silica particles when compared to the unprocessed drugs. This dissolution enhancement was attributed to the amorphisation of both drugs due to their adsorption on mesoporous silica.

Graphical Abstract

Design of GSH-Responsive Curcumin Nanomicelles for Oesophageal Cancer Therapy

Oesophageal cancer is a malignant tumor with high morbidity and mortality. Surgical treatment, radiotherapy, and chemotherapy are the most common treatment methods for oesophageal cancer. However, traditional chemotherapy drugs have poor targeting performance and cause serious adverse drug reactions. In this study, a GSH-sensitive material, ATRA-SS-HA, was developed and self-assembled with curcumin, a natural polyphenol antitumor drug, into nanomicelles Cur@ATRA-SS-HA. The micelles had a suitable particle size, excellent drug loading, encapsulation rate, stability, biocompatibility, and stable release behaviour. In the tumor microenvironment, GSH induced disulfide bond rupture in Cur@ATRA-SS-HA and promoted the release of curcumin, improving tumor targeting. Following GSH-induced release, the curcumin IC50 value was significantly lower than that of free curcumin and better than that of 5-FU. In vivo pharmacokinetic experiments showed that the drug-loaded nanomicelles exhibited better metabolic behaviour than free drugs, which greatly increased the blood concentration of curcumin and increased the half-life of the drug. The design of the nanomicelle provides a novel clinical treatment for oesophageal cancer.

Emulgels Containing Perilla frutescens Seed Oil, Moringa oleifera Seed Oil, and Mixed Seed Oil: Microemulsion and Safety Assessment

P. frutescens seed oil and M. oleifera seed oil consist of fatty acids and sterols that are beneficial for skin. Mixing of these oils at 1:1 ratio has shown to increase antioxidant activity of oils. This study aims to formulate emulgels containing microemulsions of P. frutescens seed oil, M. oleifera seed oil, and mixed P. frutescens and M. oleifera seed oils. The chemical constituents of P. frutescens seed oil, M. oleifera seed oil, and mixed seed oil are analyzed by gas chromatography/mass spectrometry (GC/MS). The microemulsions are formulated by a phase titration method and characterized for the droplet size, polydispersity index, and zeta potential value using a dynamic light scattering technique. The physical and chemical stability of the microemulsions are investigated using a rheometer and UV-Visible spectrophotometer, respectively. The safety of microemulsion is evaluated on PBMC and human subjects. Emulgels containing three different types of microemulsion are formulated. The results show that P. frutescens seed oil is mainly composed of alpha-linolenic acid, linoleic acid, and oleic acid, whereas M. oleifera seed oil contains a high proportion of oleic acid. Mixed seed oil contains a comparable amount of alpha-linolenic acid and oleic acid. All types of oils are composed of β-sitosterol as the major plant sterol. Microemulsions of all types of oils are successfully prepared by using Tween 80 as a surfactant due to the largest transparent region of pseudoternary phase diagram. The size, polydispersity index, and zeta potential values of all types of microemulsion are in the acceptable range upon storage at 30 °C for 1 month. Microemulsions exhibit pseudoplastic flow behavior. The percent of remaining oils in all types of microemulsion is more than 90% after storage at 30 °C for 1 month. Emulgels containing three types of microemulsions exhibit good characteristics and no change in viscosity after storage at 4, 30, and 45 °C for 1 month. The safety results reveal that three types of microemulsion do not induce cytotoxicity to PBMC nor induce skin irritation and allergic reactions. Emulgels containing microemulsions developed in this study can be used to safely deliver P. frutescens seed oil, M. oleifera seed oil, and mixed seed oil to human skin.

Superiority of Microemulsion-based Hydrogel for Non-Steroidal Anti-Inflammatory Drug Transdermal Delivery: A Comparative Safety and Anti-nociceptive Efficacy Study

Non-steroidal anti-inflammatory drugs (NSAIDs) represent the foundation of pain management caused by inflammatory disorders. Nevertheless, their oral administration induces several side effects exemplified by gastric ulceration, thus, delivering NSAIDs via the skin has become an attractive alternative. Herein, microemulsion-based hydrogel (MBH), proliposomal, and cubosomal gels were fabricated, loaded with diclofenac, and physicochemically characterized. The sizes, charges, surface morphologies, and the state of diclofenac within the reconstituted gels were also addressed. The release pattern and ex-vivo permeation studies using Franz cells were performed via the rat abdominal skin. The formulations were assessed in-vivo on mice skin for their irritation effect and their anti-nociceptive efficacy through the tail-flick test. Biosafety study of the optimal gel was also pointed out. The gels and their dispersion forms displayed accepted physicochemical properties. Diclofenac released in a prolonged manner from the prepared gels. MBH revealed a significantly higher skin permeation and the foremost results regarding in-vivo assessment where no skin irritation or altered histopathological features were observed. MBH further induced a significant anti-nociceptive effect during the tail-flick test with a lower tendency to evoke systemic toxicity. Therefore, limonene-containing microemulsion hydrogel is a promising lipid-based vehicle to treat pain with superior safety and therapeutic efficacy.

Microemulsion Delivery System Improves Cellular Uptake of Genipin and Its Protective Effect against Aβ1-42-Induced PC12 Cell Cytotoxicity

Genipin has attracted much attention for its hepatoprotective, anti-inflammatory, and neuroprotection activities. However, poor water solubility and active chemical properties limit its application in food and pharmaceutical industries. This article aimed to develop a lipid-based microemulsion delivery system to improve the stability and bioavailability of genipin. The excipients for a genipin microemulsion (GME) preparation were screened and a pseudo-ternary phase diagram was established. The droplet size (DS), zeta potential (ZP), polydispersity index (PDI), physical and simulated gastrointestinal digestion stability, and in vitro drug release properties were characterized. Finally, the effect of the microemulsion on its cellular uptake by Caco-2 cells and the protective effect on PC12 cells were investigated. The prepared GME had a transparent appearance with a DS of 16.17 ± 0.27 nm, ZP of −8.11 ± 0.77 mV, and PDI of 0.183 ± 0.013. It exhibited good temperature, pH, ionic strength, and simulated gastrointestinal digestion stability. The in vitro release and cellular uptake data showed that the GME had a lower release rate and better bioavailability compared with that of free genipin. Interestingly, the GME showed a significantly better protective effect against amyloid-β (Aβ1-42)-induced PC12 cell cytotoxicity than that of the unencapsulated genipin. These findings suggest that the lipid-based microemulsion delivery system could serve as a promising approach to improve the application of genipin.

DPD Simulation on the Transformation and Stability of O/W and W/O Microemulsions

The dissipative particle dynamics simulation method is adopted to investigate the microemulsion systems prepared with surfactant (H1T1), oil (O) and water (W), which are expressed by coarse-grained models. Two topologies of O/W and W/O microemulsions are simulated with various oil and water ratios. Inverse W/O microemulsion transform to O/W microemulsion by decreasing the ratio of oil-water from 3:1 to 1:3. The stability of O/W and W/O microemulsion is controlled by shear rate, inorganic salt and the temperature, and the corresponding results are analyzed by the translucent three-dimensional structure, the mean interfacial tension and end-to-end distance of H1T1. The results show that W/O microemulsion is more stable than O/W microemulsion to resist higher inorganic salt concentration, shear rate and temperature. This investigation provides a powerful tool to predict the structure and the stability of various microemulsion systems, which is of great importance to developing new multifunctional microemulsions for multiple applications.

Surface Modification of Curcumin Microemulsions by Coupling of KLVFF Peptide: A Prototype for Targeted Bifunctional Microemulsions

Curcumin is one of the most promising natural therapeutics for use against Alzheimer's disease. The major limitations of curcumin are its low oral bioavailability and difficulty in permeating the blood-brain barrier. Therefore, designing a delivery system of curcumin to overcome its limitations must be employed. KLVFF, a peptide known as an amyloid blocker, was used in this study as a targeting moiety to develop a targeted drug delivery system. A prototype of transnasal KLVFF conjugated microemulsions containing curcumin (KLVFF-Cur-ME) for the nose-to-brain delivery was fabricated. The KLVFF-Cur-ME was developed by a titration method. A conjugation of KLVFF was performed through a carbodiimide reaction, and the conjugation efficiency was confirmed by FTIR and DSC technique. KLVFD-Cur-ME was characterized for the drug content, globule size, zeta potential, and pH. A transparent and homogeneous KLVFF-Cur-ME is achieved with a drug content of 80.25% and a globule size of 76.1 ± 2.5 nm. The pH of KLVFF-Cur-ME is 5.33 ± 0.02, indicating non-irritation to nasal tissues. KLVFD-Cur-ME does not show nasal ciliotoxicity. An ex vivo diffusion study revealed that KLVFF-Cur-ME partitions the porcine nasal mucosa through diffusion, following the Higuchi model. This investigation demonstrates the successful synthesis of a bifunctional KLVFF-Cur-ME as a novel prototype to deliver anti-Aβ aggregation via an intranasal administration.

Microemulsion Based Nanostructures for Drug Delivery

Most of the active pharmaceutical compounds are often prone to display low bioavailability and biological degradation represents an important drawback. Due to the above, the development of a drug delivery system (DDS) that enables the introduction of a pharmaceutical compound through the body to achieve a therapeutic effect in a controlled manner is an expanding application. Henceforth, new strategies have been developed to control several parameters considered essential for enhancing delivery of drugs. Nanostructure synthesis by microemulsions (ME) consist of enclosing a substance within a wall material at the nanoscale level, allowing to control the size and surface area of the resulting particle. This nanotechnology has shown the importance on targeted drug delivery to improve their stability by protecting a bioactive compound from an adverse environment, enhanced bioavailability as well as controlled release. Thus, a lower dose administration could be achieved by minimizing systemic side effects and decreasing toxicity. This review will focus on describing the different biocompatible nanostructures synthesized by ME as controlled DDS for therapeutic purposes.

Relative bioavailability enhancement of simvastatin via dry emulsion systems: comparison of spray drying and fluid bed layering technology

Comprehensive comparisons of similar lipid based drug delivery systems produced by different technologies are scarce. Spray drying and fluid bed layering technologies were compared with respect to the process and product characteristics of otherwise similar simvastatin loaded dry emulsion systems. Fluid bed layering provided higher process yield (83.3% vs 71.5%), encapsulation efficiency (80.0% vs 68.4 %), relative one month product stability (93.8% vs 85.5%), larger and more circular particles (336 µm vs 56 µm) and lower median oil droplet size after product reconstitution in water (2.85 µm vs 4.27 µm), compared to spray drying. However, spray dried products exhibited higher drug content (22.2 mg/g vs 9.34 mg/g). An in-vivo pharmacokinetic study in rats was performed and a pharmacokinetic model was developed in order to compare the optimised simvastatin loaded dry emulsion systems, a simvastatin glyceride mimetic loaded in the dry emulsion and a simvastatin loaded SMEDDS with a reference physical mixture. Of the formulation tested, fluid bed layered pellets excelled and provided a 115% relative increase in bioavailability. Among the two technologies, fluid bed layering provided dry emulsion products with higher relative bioavailability and better product characteristics for further processing into final dosage forms.

Enhancement of the Topical Bioavailability and Skin Whitening Effect of Genistein by Using Microemulsions as Drug Delivery Carriers

Genistein, the most abundant isoflavone of the soy-derived phytoestrogen compounds, is a potent antioxidant and inhibitor of tyrosine kinase, which can inhibit UVB-induced skin carcinogenesis in hairless mice and UVB-induced erythema on human skin. In current study, genistein-loaded microemulsions were developed by using the various compositions of oil, surfactants, and co-surfactants and used as a drug delivery carrier to improve the solubility, peremability, skin whitening, and bioavailbility of genistein. The mean droplet size and polydispersity index of all formulations was less than 100 nm and 0.26 and demonstrated the formation of microemulsions. Similarly, various studies, such as permeation, drug skin deposition, pharmacokinetics, skin whitening test, skin irritation, and stability, were also conducted. The permeability of genistein was significantly affected by the composition of microemulsion formulation, particular surfactnat, and cosurfactant. In-vitro permeation study revealed that both permeation rate and deposition amount in skin were significantly increased from 0.27 μg/cm²·h up to 20.00 μg/cm²·h and 4.90 up to 53.52 μg/cm², respectively. In in-vivo whitening test, the change in luminosity index (ΔL*), tended to decrease after topical application of genistein-loaded microemulsion. The bioavailability was increased 10-fold by topical administration of drug-loaded microemulsion. Conclusively, the prepared microemulsion has been enhanced the bioavailability of genistein and could be used for clinical purposes.

A practical strategy to subcutaneous administered in-situ gelling co-delivery system of arsenic and retinoic acid for the treatment of acute promyelocytic leukemia

Arsenic trioxide (ATO) combined with all trans retinoic acid (ATRA) is the first choice for the treatment of low and medium risk acute promyelocytic leukemia (APL). Clinical studies reported that the combination of ATO and ATRA could achieve a significant curative effect. However, the retinoic acid syndrome, serious drug resistance and the short half-life in vivo which lead to frequent and large dose administration limit the application of ATRA. In addition, the preparations of arsenic are conventional injections and tablets in clinic, which has poor patients' compliance caused by frequent long-term administration and serious side effects. In order to overcome the above limitations, a phospholipid phase separation gel (PPSG) loaded with ATO and ATRA was developed. ATO+ATRA-PPSG (AAP), as a biodegradable sustained-release delivery system, was the first achievement of co-delivery of hydrophilic ATO and lipophilic ATRA with high drug loading which is the main problem in the application of nano preparation. The prepared PPSG displayed high safety and biocompatibility. The drug in PPSG was released slowly and continuously in vivo and in vitro for up to 10 d, which could reduce the side effects caused by the fluctuation of blood drug concentration and solve the problem of the long treatment cycle and frequent administration. In vivo pharmacokinetics depicted that PPSG could improve the bioavailability, decrease the peak concentration, and prolong the t1/2 of ATO and ATRA. Particularly, AAP significantly inhibited the tumor volume, extended the survival period of tumor-bearing mice, and promoted the differentiation of APL cells into normal cells. Therefore, ATO+ATRA-PPSG not only could co-load hydrophilic ATO and lipophilic ATRA according to the clinical dosage, but also possessed the sustained-release and long-acting treatment effect which was expected to reduce administration time and ameliorate compliance of patients. Thus, it had great potential for clinical transformation and application.

Recent Technologies for Amorphization of Poorly Water-Soluble Drugs

Amorphization technology has been the subject of continuous attention in the pharmaceutical industry, as a means to enhance the solubility of poorly water-soluble drugs. Being in a high energy state, amorphous formulations generally display significantly increased apparent solubility as compared to their crystalline counterparts, which may allow them to generate a supersaturated state in the gastrointestinal tract and in turn, improve the bioavailability. Conventionally, hydrophilic polymers have been used as carriers, in which the amorphous drugs were dispersed and stabilized to form polymeric amorphous solid dispersions. However, the technique had its limitations, some of which include the need for a large number of carriers, the tendency to recrystallize during storage, and the possibility of thermal decomposition of the drug during preparation. Therefore, emerging amorphization technologies have focused on the investigation of novel amorphous-stabilizing carriers and preparation methods that can improve the drug loading and the degree of amorphization. This review highlights the recent pharmaceutical approaches utilizing drug amorphization, such as co-amorphous systems, mesoporous particle-based techniques, and in situ amorphization. Recent updates on these technologies in the last five years are discussed with a focus on their characteristics and commercial potential.

3D Printing of Dapagliflozin Containing Self-Nanoemulsifying Tablets: Formulation Design and In Vitro Characterization

The 3D printing techniques have been explored extensively in recent years for pharmaceutical manufacturing and drug delivery applications. The current investigation aims to explore 3D printing for the design and development of a nanomedicine-based oral solid dosage form of a poorly water-soluble drug. A self-nanoemulsifying tablet formulation of dapagliflozin propanediol monohydrate was developed utilizing the semisolid pressure-assisted microsyringe (PAM) extrusion-based 3D printing technique. The developed formulation system consists of two major components (liquid and solid phase), which include oils (caproyl 90, octanoic acid) and co-surfactant (PEG 400) as liquid phase while surfactant (poloxamer 188) and solid matrix (PEG 6000) as solid-phase excipients that ultimately self-nanoemulsify as a drug encapsulated nanoemulsion system on contact with aqueous phase/gastrointestinal fluid. The droplet size distribution of the generated nanoemulsion from a self-nanoemulsifying 3D printed tablet was observed to be 104.7 ± 3.36 nm with polydispersity index 0.063 ± 0.024. The FT-IR analysis of the printed tablet revealed that no drug-excipients interactions were observed. The DSC and X-RD analysis of the printed tablet revealed that the loaded drug is molecularly dispersed in the crystal lattice of the tablet solid matrix and remains solubilized in the liquid phase of the printed tablet. SEM image of the drug-loaded self-nanoemulsifying tablets revealed that dapagliflozin propanediol monohydrate was completely encapsulated in the solid matrix of the printed tablet, which was further confirmed by SEM-EDS analysis. The in vitro dissolution profile of dapagliflozin-loaded self-nanoemulsifying tablet revealed an immediate-release drug profile for all three sizes (8 mm, 10 mm, and 12 mm) tablets, exhibiting >75.0% drug release within 20 min. Thus, this study has emphasized the capability of the PAM-based 3D printing technique to print a self-nanoemulsifying tablet dosage form with an immediate-release drug profile for poorly water-soluble drug.

Preclinical Assessment Addressing Intravenous Administration of a [68Ga]Ga-PSMA-617 Microemulsion: Acute In Vivo Toxicity, Tolerability, PET Imaging, and Biodistribution

It has been herein presented that a microemulsion, known to be an effective and safe drug delivery system following intravenous administration, can be loaded with traces of [⁶⁸Ga]Ga-PSMA-617 without losing its properties or causing toxicity. Following tolerated IV injections the capability of the microemulsion in altering [⁶⁸Ga]Ga-PSMA-617 distribution was presented at 120 min post injection based on its ex vivo biodistribution results.

Tailored Limonene-Based Nanosized Microemulsion: Formulation, Physicochemical Characterization and In Vivo Skin Irritation Assessment

Purpose: Microemulsion (ME) achieved progressing consequences on both the research and industry levels due to their distinctive properties. ME based-limonene system is considered as a surrogate to the traditional microemulsion composed of conventional oils. Thus, a novel microemulsion based on D-limonene and Gelucire® 44/12 had been designed and evaluated with assessing the factors affecting its physicochemical characteristics and in vivo skin irritation.

Methods: The impact of microemulsion components and ratios on the isotropic region of the pseudo-ternary phase diagram was investigated. The optimal formula was evaluated in terms of percentage transmittance, average globule size, size distribution, zeta potential, microscopical morphology, stability under different storage conditions and its effect on the mice ear skin.

Results: The results demonstrated that Labrasol® and Labrafil® M 1944 CS had been selected as surfactant and co-surfactant, respectively, due to their emulsifying abilities. The largest isotropic area in the pseudo-ternary phase diagram was at a weight ratio of 4:1 for Labrasol® and Labrafil® M 1944 CS. The optimized microemulsion with 25% w/w of the lipid phase and 58.3% w/w of the aqueous phase displayed an optical transparency of 96.5±0.88 %, average globule size of 125±0.123 nm, polydispersity index of 0.272±0.009, zeta potential of -18.9± 2.79 mV with rounded globules morphology and high stability. The in vivo skin irritation and the histopathological evaluation of microemulsion elucidated its safety profile when applied on the skin.

Conclusion: The formulated microemulsion is a prospective aid for an essential oil to minimize its volatility, enhance its stability, and mask its dermal irritant.

Effect of peppermint oil and its microemulsion on necrotic enteritis in broiler chickens

Background and Aim:

Clostridium perfringens is one of the multiple drug-resistant intestinal pathogens causing necrotic enteritis disease, leading to great economic losses in poultry farms. This study aimed to evaluate the potential use of peppermint oil and its microemulsion (ME) as an alternative to antibiotics to control necrotic enteritis in broiler chickens.

Materials and Methods:

Peppermint oil ME formulation (15% oil/water) was prepared and characterized by zeta potential, Fourier transform infrared, high-resolution transmission electron microscopy, and liquid chromatography–mass spectrometry (LC-MS/MS). The minimal inhibitory concentrations of the peppermint oil and its ME were investigated. A total of 80 commercial one day old Arbor Acres broiler chickens were randomly assigned to four groups of 20 birds each. The four groups were the negative control, positive control, peppermint oil (0.5 mL/mL water/10 days old), and its ME (0.25 mL/mL water/10 days old) groups. C. perfringens was orally provided at concentration of 1×10⁸ CFU/mL on days 14, 15, and 16. Clinical signs and mortality were observed daily. Growth performance, gross lesions and cecal samples were investigated and examined on days 21, 28, and 35.

Results:

Peppermint oil ME formulation has a polydispersity index, zeta potential and droplet size of 0.234, −24 mV±4.19, and 29.96±1.56 nm, respectively. LC–MS/MS analysis of oil and ME revealed common presence of phenolic compounds such as rosmorinic (360.31 g/mol), chlorogenic acid (354.31 g/mol), hesperidin (610.56 g/mol), and luteolin 7-O-β-glucuronide (462.1 g/mol). The treated groups with peppermint oil and ME showed lower lesions, mortality and colony-forming units in addition to higher growth performance (p < 0.05) compared to the positive control group.

Conclusion:

Our study suggests the potential efficacy of peppermint oil and ME in the reduction of necrotic enteritis lesions and C. perfringens count.

Curcumin-Loaded Self-Microemulsifying Gel for Enhancing Wound Closure

INTRODUCTION

Wound healing is a process in which damaged cutaneous tissues are repaired and is a dynamic physiological interaction involving several types of cells, tissues, and proteins. Compared with typical treatments, specifically in terms of multifunctional properties, bioactive drug-loaded wound dressing in a controlled and sustained delivery system is an advanced tool that significantly improves wound healing. Curcumin substantially enhances wound healing and prevents oxidative damage. However, the effects of this compound on improving wound healing are limited by its aqueous solubility, poor tissue absorption, and rapid metabolism. Hence, the current study aimed to investigate the therapeutic effect of curcumin-loaded self-microemulsifying gel on wound healing.

METHODS

Ex vivo permeation studies of the skin of BALB/c mice were performed using a diffusion cell sampling system. The in vivo therapeutic effect was investigated with a full-thickness wound model. Two 6-mm full-thickness circular wounds were created on the back of the mice via punch biopsy. Then, they received different topical gels for 12 days to enhance wound closure.

RESULTS

The curcumin-loaded self-microemulsifying gel had higher skin flux, cumulative amount, and permeability coefficient than the commercial gels. In addition, it enhanced wound healing.

CONCLUSIONS

This is the first study that utilized self-microemulsifying gel loaded with curcumin as a delivery system for wound healing. However, the effect of this delivery system on wound healing or skin disease treatment should be further investigated.

Development of Microemulsions Containing Glochidion wallichianum Leaf Extract and Potential for Transdermal and Topical Skin Delivery of Gallic Acid

Glochidion wallichianum (GW) is a good source of antioxidants, including gallic acid, promoting its development as a microemulsion. We constructed five pseudo-ternary phase diagrams comprising isopropyl myristate (IPM), water, and surfactant mixture (Smix)—i.e., Labrasol®:HCO-40® (1:1) with Transcutol® (1:1, 2:1, 3:1), and Tween80:Span80 (3:2) with Transcutol® or propylene glycol:ethanol (1:1). Additionally, blank and GW extract-loaded microemulsions were prepared at an IPM:Water:Smix ratio of 10:30:60 (high water content) and 30:10:60 (high oil content) from each Smix. The physical characteristics, skin permeation, and disposition were evaluated. The formulations with high water content and conductivities provided higher gallic acid permeation and disposition than those with high oil content. The Smix of Labrasol®:HCO-40® (1:1) and Transcutol® (1:1) promoted the highest gallic acid permeation (enhancement ratio 1.78 ± 0.12) and was suitable for transdermal delivery. However, the 1% hydroxypropyl methylcellulose control gel, the microemulsion with Smix of Labrasol®:HCO-40® (1:1) with Transcutol® (2:1), and Smix of Tween80:Span80 (3:2) with propylene glycol:ethanol (1:1) could provide higher skin accumulation of gallic acid than that with other formulations. The microstructures, ratio of surfactant:cosurfactant, and compositions of microemulsions were found to affect the skin permeation and disposition of gallic acid and require optimization to act as transdermal or topical delivery carriers.

CYP3A Excipient-Based Microemulsion Prolongs the Effect of Magnolol on Ischemia Stroke Rats

Magnolol, which is a CYP3A substrate, is a well-known agent that can facilitate neuroprotection and reduce ischemic brain damage. However, a well-controlled release formulation is needed for the effective delivery of magnolol due to its poor water solubility. In this study, we have developed a formulation for a CYP3A-excipient microemulsion, which can be administrated intraperitoneally to increase the solubility and bioavailability of magnolol and increase its neuroprotective effect against ischemic brain injury. The results showed a significant improvement in the area under the plotted curve of drug concentration versus time curve (AUC0–t) and mean residence time (MRT) of magnolol in microemulsion compared to when it was dissolved in dimethyl sulfoxide (DMSO). Both magnolol in DMSO and microemulsion, administrated after the onset of ischemia, showed a reduced visual brain infarct size. As such, this demonstrates a therapeutic effect on ischemic brain injury caused by occlusion, however it is important to note that a pharmacological effect cannot be concluded by this study. Ultimately, our study suggests that the excipient inhibitor-based microemulsion formulation could be a promising concept for the substrate drugs of CYP3A.

Current Trends in ATRA Delivery for Cancer Therapy

All-Trans Retinoic Acid (ATRA) is the most active metabolite of vitamin A. It is critically involved in the regulation of multiple processes, such as cell differentiation and apoptosis, by activating specific genomic pathways or by influencing key signaling proteins. Furthermore, mounting evidence highlights the anti-tumor activity of this compound. Notably, oral administration of ATRA is the first choice treatment in Acute Promyelocytic Leukemia (APL) in adults and NeuroBlastoma (NB) in children. Regrettably, the promising results obtained for these diseases have not been translated yet into the clinics for solid tumors. This is mainly due to ATRA-resistance developed by cancer cells and to ineffective delivery and targeting. This up-to-date review deals with recent studies on different ATRA-loaded Drug Delivery Systems (DDSs) development and application on several tumor models. Moreover, patents, pre-clinical, and clinical studies are also reviewed. To sum up, the main aim of this in-depth review is to provide a detailed overview of the several attempts which have been made in the recent years to ameliorate ATRA delivery and targeting in cancer.

Salvianolic Acid B in Microemulsion Formulation Provided Sufficient Hydration for Dry Skin and Ameliorated the Severity of Imiquimod-Induced Psoriasis-Like Dermatitis in Mice

Psoriasis is a chronic inflammatory skin disorder with a pathogenesis involving the interleukin-23/interleukin-17 axis. Salvianolic acid B exerts several pharmacological effects, such as antioxidation, anti-inflammation, and antitumor effects. The anti-psoriatic effects of salvianolic acid B have not been reported. In this study, we aimed to determine the optimum vehicle for salvianolic acid B, investigate its therapeutic effect on psoriatic-like skin conditions, and explore its underlying mechanisms of action. BALB/c mice were administered topical imiquimod to induce psoriasis-like skin and were then randomly assigned to control, vehicle control, salvianolic acid B in vehicles, and 0.25% desoximetasone ointment treatment groups. Barrier function, cytokine expression, histology assessment, and disease severity were evaluated. The results showed that salvianolic acid B-containing microemulsion alleviated disease severity, reduced acanthosis, and inhibited interleukin-23/interleukin-17 (IL-23/IL-17) cytokines, epidermal proliferation, and increased skin hydration. Our study suggests that salvianolic acid B represents a possible new therapeutic drug for the treatment of psoriasis. In addition, such formulation could obtain high therapeutic efficacy in addition to providing sufficient hydration for dry skin.

Oral delivery of lycopene-loaded microemulsion for brain-targeting: preparation, characterization, pharmacokinetic evaluation and tissue distribution

Lycopene is considered as a promising neuroprotector with multiple bioactivities, while its therapeutic use in neurological disorders is restricted due to low solubility, instability and limited bioavailability. Our work aimed to develop lycopene-loaded microemulsion (LME) and investigate its potentials in improving bioavailability and brain-targeting efficiency following oral administration. The blank microemulsion (ME) excipients were selected based on orthogonal design and pseudo-ternary phase diagrams, and LME was prepared using the water titration method and characterized in terms of stability, droplet size distribution, zeta potential, shape and lycopene content. The optimized LME encompassed lycopene, (R)-(+)-limonene, Tween 80, Transcutol HP and water and lycopene content was 463.03 ± 8.96 µg/mL. This novel formulation displayed transparent appearance and satisfactory physical and chemical stabilities. It was spherical and uniform in morphology with an average droplet size of 12.61 ± 0.46 nm and a polydispersity index (PDI) of 0.086 ± 0.028. The pharmacokinetics and tissue distributions of optimized LME were evaluated in rats and mice, respectively. The pharmacokinetic study revealed a dramatic 2.10-fold enhancement of relative bioavailability with LME against the control lycopene dissolved in olive oil (LOO) dosage form in rats. Moreover, LME showed a preferential targeting distribution of lycopene toward brain in mice, with the value of drug targeting index (DTI) up to 3.45. In conclusion, the optimized LME system demonstrated excellent physicochemical properties, enhanced oral bioavailability and superior brain-targeting capability. These findings provide a basis for the applications of ME-based strategy in brain-targeted delivery via oral route, especially for poorly water-soluble drugs.

Multicompartmental lipid–protein nanohybrids for combined tretinoin/herbal lung cancer therapy

Aim: Multicompartmental lipid–protein nanohybrids (MLPNs) were developed for combined delivery of the anticancer drugs tretinoin (TRE) and genistein (GEN) as synergistic therapy of lung cancer. Materials & methods: The GEN-loaded lipid core was first prepared and then coated with TRE-loaded zein shell via nanoprecipitation. Results: TRE/GEN-MLPNs demonstrated a size of 154.5 nm. In situ ion pair formation between anionic TRE and the cationic stearyl amine improved the drug encapsulation with enhanced stability of MLPNs. TRE/GEN-coloaded MLPNs were more cytotoxic against A549 cancer cells compared with combined free GEN/TRE. In vivo, lung cancer bearing mice treated with TRE/GEN-MLPNs displayed higher apoptotic caspase activation compared with mice-treated free combined GEN/TRE. Conclusion: TRE/GEN-MLPNs might serve as a promising parenteral nanovehicles for lung cancer therapy.

Development and mechanistic study of a microemulsion containing vitamin E TPGS for the enhancement of oral absorption of celecoxib

Purpose: The purpose of this study was to develop a microemulsion containing D-α-tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS) as a biodegradable surfactant to increase the oral absorption of celecoxib. Methods: This study investigated the intestinal absorption enhancement mechanism of this microemulsion by measuring transepithelial electrical resistance (TEER) values. This study also evaluated microemulsion particle-intestine interactions in terms of release and attachment processes using confocal laser scanning microscopy (CLSM). Results: The prepared microemulsion particles had a size of <300 nm with a neutral surface charge. The celecoxib-loaded microemulsion release kinetic was classified as the zero-order model. This vitamin E TPGS-based microemulsion significantly increased the in vitro intestinal absorption of celecoxib compared to celecoxib solution. The CLSM study suggested that microemulsion particles with entrapped drugs might attach to the intestinal epithelium before releasing the entrapped drug into tissues. The TEER value of the intestinal tissues treated with the celecoxib-loaded microemulsion was significantly decreased compared to the value before treatment, indicating an increase in drug transport via the paracellular pathway. The evaluation of intestinal tissue cytotoxicity using lactate dehydrogenase cytotoxicity assay suggested that the prepared celecoxib-loaded microemulsion was safe for oral route administration. Conclusions: The prepared celecoxib loaded microemulsion could increase the intestinal absorption of celecoxib compared to celecoxib solution. The intestinal absorption enhancement mechanism of this microemulsion resulted from the increase of the drug transport via the paracellular pathway.

Preparation of α-Linolenic-Acid-Loaded Water-in-Oil-in-Water Microemulsion and Its Potential as a Fluorescent Delivery Carrier with a Free Label

Our previous work has demonstrated that α-linolenic acid (ALA)-loaded oil-in-water (O/W) microemulsion could enhance ALA antioxidant capacity. Meanwhile, we also observed that synthesized microemulsion itself had fluorescence. In this work, we have prepared a multiple water-in-oil-in-water (W/O/W) microemulsion to further enhance ALA antioxidant capacity and activate this delivery carrier application potential with a free label. The compositions of primary water-in-oil (W/O) microemulsion were obtained using pseudo-ternary phase diagrams, and then W/O/W microemulsion was prepared adopting the "two-step heterotherm method". The conductivity of W/O/W microemulsion was measured to lie between 250.0 and 350.0 μs/cm. The spherical droplets with a mean particle diameter of 10.0-20.0 nm were confirmed by transmission electron microscopy and dynamic light scattering. Nuclear magnetic resonance confirmed that ALA diffused to the multiple water-oily interface simultaneously. In addition, the in vitro release and antioxidant capacity measurements of ALA-loaded W/O/W microemulsion concluded the sustained-release effect and excellent antioxidant capacity. The fluorescent intensity of W/O/W microemulsion was markedly increased in comparison to O/W microemulsion. The synthesized microemulsion could lead to important applications and have advantages of a label-free fluorescent carrier for optical imaging purposes.

Development of Triamcinolone Acetonide-Loaded Nanostructured Lipid Carriers (NLCs) for Buccal Drug Delivery Using the Box-Behnken Design

The aim of this present work was to prepare triamcinolone acetonide (TA)-loaded nanostructured lipid carriers (TA-loaded NLCs) for buccal drug delivery systems using the Box-Behnken design. A hot homogenization method was used to prepare the TA-loaded NLCs. Spermaceti (X₁), soybean oil (X₂), and Tween 80 (X₃) were used as solid lipid, liquid lipid, and stabilizer, respectively. The particle size of TA-loaded NLCs was lower than 200 nm and the zeta potential displayed the negative charge in all formulations. The percentage encapsulation efficiency (%EE) of the TA-loaded NLCs showed that it was higher than 80% for all formulations. Field emission scanning electron microscope (FESEM) confirmed that the size of TA-loaded NLCs was approximately 100 nm and energy-dispersive X-ray spectroscopy (EDS) confirmed that the TA could be incorporated in the NLC system. The Higuchi model gave the highest value of the R², indicating that this model was a fit for the TA release profiles of TA-loaded NLCs. Confocal laser scanning microscopy (CLSM) was used to observe the drug penetration within the porcine buccal mucosa and Nile red-loaded NLCs showed significantly higher penetration depth at 8 h than at 2 h. Therefore, TA-loaded NLCs could be an efficient carrier for drug delivery through the buccal mucosa.